Vitamin D supplementation reduces insulin resistance in Japanese adults: a secondary analysis of a double-blind, randomized, placebo-controlled trial. Effect of vitamin D supplementation on glycemic control in patients with type 2 diabetes: a systematic review of interventional studies The effect of different doses of vitamin D supplementation on insulin resistance during pregnancy A double-blind, randomized, placebo-controlled trial of the short-term effect of vitamin D3 supplementation on insulin sensitivity in apparently healthy, middle-aged, centrally obese men. Effect of short-term vitamin D supplementation on markers of vascular health in South Asian women living in the UK--a randomised controlled trial. Effect of Vitamin K Supplementation on Insulin Resistance in Older Men and Women Effects of a 1-year supplementation with cholecalciferol on interleukin-6, tumor necrosis factor-alpha and insulin resistance in overweight and obese subjects. Vitamin D supplementation reduces insulin resistance in South Asian women living in New Zealand who are insulin resistant and vitamin D deficient - a randomised, placebo-controlled trial. Vitamin D supplementation has no effect on insulin resistance assessment in women with polycystic ovary syndrome and vitamin D deficiency. Effect of supplementation with tomato juice, vitamin E, and vitamin C on LDL oxidation and products of inflammatory activity in type 2 diabetes. Vitamin D supplementation has no effect on insulin sensitivity or secretion in vitamin D-deficient, overweight or obese adults: a randomized placebo-controlled trial. Vitamin D supplementation for the prevention of type 2 diabetes in overweight adults: study protocol for a randomized controlled trial The Impact of Vitamin D Supplementation on Post-Partum Glucose Tolerance and Insulin Resistance in Gestational Diabetes: A Randomized Controlled Trial Effects of vitamin D and calcium supplementation on pancreatic β cell function, insulin sensitivity, and glycemia in adults at high risk of diabetes: the Calcium and Vitamin D for Diabetes Mellitus (CaDDM) randomized controlled trial. Effect of various doses of vitamin D supplementation on pregnant women with gestational diabetes mellitus: A randomized controlled trial. Effect of moderate-dose vitamin D supplementation on insulin sensitivity in vitamin D-deficient non-Western immigrants in the Netherlands: a randomized placebo-controlled trial. Low maternal vitamin B-12 status is associated with offspring insulin resistance regardless of antenatal micronutrient supplementation in rural Nepal. Study protocol: a randomised placebo-controlled clinical trial to study the effect of vitamin D supplementation on glycaemic control in type 2 Diabetes Mellitus SUNNY trial Effects of vitamin D supplementation and exercise training on physical performance in Chilean vitamin D deficient elderly subjects The effect of high-dose vitamin D supplementation on insulin resistance and arterial stiffness in patients with type 2 diabetes Effect of vitamin and trace-element supplementation on cognitive function in elderly subjects. Vitamin D and Evening Primrose Oil Administration Improve Glycemia and Lipid Profiles in Women with Gestational Diabetes Insulin-like growth factor I, growth hormone, and insulin sensitivity: the effects of a one-year cholecalciferol supplementation in middle-aged overweight and obese subjects
Higher circulating 25-hydroxyvitamin D ( 25[OH]D ) concentration has been linked to a lower prevalence of insulin resistance and type 2 diabetes mellitus . However , r and omized controlled trials have not clarified the effect of vitamin D supplementation on insulin resistance in healthy adults . The objective of this study was to assess the effect of vitamin D supplementation for 1 year on insulin resistance ; the study was a secondary analysis of a clinical trial . We hypothesized that increased 25(OH)D concentration after vitamin D supplementation for 1 year would significantly improve insulin resistance .  Ninety-six healthy adults participated in this study , of whom 81 completed the study . The participants r and omly received daily either 420 IU vitamin D3 or placebo in a double-blind manner for 1 year . The levels of fasting insulin , glucose , and other parameters were assessed at baseline and after 1 year of intervention . Homeostasis model assessment of insulin resistance index was calculated from insulin and glucose levels . Visceral fat area and physical activity were also investigated . Serum 25(OH)D and 1,25-dihydroxyvitamin D concentrations were significantly increased by approximately 29.5 nmol/L and 7.0 pg/mL , respectively , after 1-year vitamin D supplementation . After vitamin D supplementation , fasting glucose levels and values of homeostasis model assessment of insulin resistance index significantly decreased from 88.3 to 85.3 mg/dL ( P < .01 ) and 1.17 to 0.84 ( P < .01 ) , respectively , and the results were independent of physical activity and visceral fat accumulation . In conclusion , the present study showed that vitamin D supplementation for 1 year effectively improves fasting glucose level and insulin resistance in healthy Japanese adults Background Diabetes and vitamin D deficiency are global epidemics . Research ers have long been exploring the role of potentially modifiable factors to manage type 2 diabetes . We conducted a systematic review of prospect i ve studies and r and omized controlled trials that involved vitamin D supplementation and specifically intended to study glycemic outcomes related to type 2 diabetes . Methods Two authors independently search ed Medline and PubMed for longitudinal studies that had assessed the effect of vitamin D supplements on glycemic control , insulin resistance and beta-cell dysfunction in patients with diabetes . Results Seventeen r and omized control trials and seven longitudinal studies with a minimum follow-up of one month were included . Results of the various short-term studies ( follow up ≤ 3 months ) suggested that vitamin D supplementation had a positive impact on glycemic control and metabolic parameters such as insulin resistance and beta cell dysfunction . However , the evidence was weak due to the low method ological quality of the studies . There was no significant effect on HbA1c , beta cell function and insulin resistance in the long-term studies ( follow up > 3 months ) . There existed heterogeneity in the methodology of the studies , inclusion criteria , mode of supplementation of vitamin D and the duration of follow up . Conclusions Current evidence based on r and omized controlled trials and longitudinal studies do not support the notion that vitamin D supplementation can improve hyperglycemia , beta cell secretion or insulin sensitivity in patients with type 2 diabetes . Large-scale trials with proper study design , optimal vitamin D supplementation and longer follow up need to be conducted Abstract Low serum vitamin D levels are correlated with insulin resistance during pregnancy . We have assessed the effects of different doses of vitamin D on insulin resistance during pregnancy . A r and omized clinical trial was done on 120 women with a gestational age of less than 12 weeks . The women were divided into three groups r and omly . Group A received 200 IU vitamin D daily , group B 50 000 IU vitamin D monthly and group C 50 000 IU vitamin D every 2 weeks from 12 weeks of pregnancy until delivery . The serum levels of fasting blood sugar ( FBS ) , insulin , calcium and 25-hydroxyvitamin D were measured before and after intervention . We used the homeostatic model assessment of insulin resistance ( HOMA-IR ) as a surrogate measure of insulin resistance . The mean ± st and ard deviation of serum 25-hydroxyvitamin D increased in group C from 7.3 ± 5.9 to 34.1 ± 11.5 ng/ml and in group B it increased from 7.3 ± 5.3 to 27.23 ± 10.7 ng/ml , but the level of vitamin D in group A increased from 8.3 ± 7.8 to 17.7 ± 9.3 ng/ml ( p < 0.001 ) . The mean differences of insulin and HOMA-IR before and after intervention in groups A and C were significant ( p = 0.01 , p = 0.02 ) . This study has shown that supplementation of pregnant women with 50 000 IU vitamin D every 2 weeks improved insulin resistance significantly AIM To determine the short-term effect of vitamin D(3 ) supplementation on insulin sensitivity in apparently healthy , middle-aged , central ly obese men . SUBJECTS AND METHODS A double-blind r and omized controlled trial was conducted at a tertiary care facility in which 100 male volunteers aged > or = 35 years received three doses of vitamin D(3 ) ( 120,000 IU each ; supplemented group ) fortnightly or placebo ( control group ) . Hepatic fasting insulin sensitivity [ homeostasis model assessment ( HOMA ) , quantitative insulin-sensitivity check index , HOMA-2 ] , postpr and ial insulin sensitivity [ oral glucose insulin sensitivity ( OGIS ) ] , insulin secretion ( HOMA%B , HOMA2-%B ) , lipid profile and blood pressure were measured at baseline and at 6 weeks ' follow-up . RESULTS Seventy-one of the recruited subjects completed the study ( 35 in supplemented group , 36 in control group ) . There was an increase in OGIS with supplementation by per protocol analysis ( P = 0.038 ; intention-to-treat analysis P = 0.055 ) . The age- and baseline 25-hydroxyvitamin D level-adjusted difference in change in OGIS was highly significant ( mean difference 41.1 + /- 15.5 ; P = 0.01 ) . No changes in secondary outcome measures ( insulin secretion , basal indices of insulin sensitivity , blood pressure or lipid profile ) were found with supplementation . CONCLUSION The trial indicates that vitamin D(3 ) supplementation improves postpr and ial insulin sensitivity ( OGIS ) in apparently healthy men likely to have insulin resistance ( central ly obese but non-diabetic ) OBJECTIVE Low vitamin D levels and risk factors for vascular disease are both common in South Asian women . This trial evaluated whether vitamin D supplementation could improve markers of vascular health in South Asian women with low 25-hydroxyvitamin D levels . METHODS Parallel-group , double-blind , r and omised placebo-controlled trial . Healthy South Asian women with baseline serum 25-hydroxyvitamin D levels of < 75 nmol/L were r and omised to receive a single dose of 100,000 units oral vitamin D3 or matching placebo . Outcomes were measured at baseline , 4 and 8 weeks . The primary outcome was change in endothelial function measured using brachial artery flow-mediated dilatation . Secondary outcomes included blood pressure , arterial stiffness , microvascular function measured using laser Doppler iontophoresis , insulin resistance , serum lipids , circulating markers of inflammation , thrombosis and adipokines . RESULTS 50 women were r and omised , 25 to each group . Mean age was 41 years ; mean baseline 25-hydroxyvitamin D level was 27 nmol/L.  25-Hydroxyvitamin D levels rose in the vitamin D group relative to the placebo group by 4 weeks ( 16 nmol/L , 95 % CI 11 to 21 , p < 0.001 ) . There was no improvement in flow-mediated dilatation in the vitamin D group relative to placebo at 4 weeks ( 0.1 % , 95 % CI -0.9 to 1.1 , p = 0.84 ) or 8 weeks ( 0.0 % , 95 % CI -1.4 to 1.4 , p = 0.98 ) . There was no improvement in cholesterol , insulin resistance or markers of inflammation . Both platelet activation inhibitor-1 and tissue plasminogen activator levels fell significantly in the vitamin D group relative to placebo at 8 weeks . CONCLUSION A single large dose of vitamin D3 did not improve blood pressure or endothelial function in South Asian women with low baseline 25-hydroxyvitamin D levels . TRIAL REGISTRATION IS RCT N75081811 OBJECTIVE —Vitamin K has a potentially beneficial role in insulin resistance , but evidence is limited in humans . We tested the hypothesis that vitamin K supplementation for 36 months will improve insulin resistance in older men and women . RESEARCH DESIGN AND METHODS —This was an ancillary study of a 36-month , r and omized , double-blind , controlled trial design ed to assess the impact of supplementation with 500 μg/day phylloquinone on bone loss . Study participants were older nondiabetic men and women ( n = 355 ; aged 60–80 years ; 60 % women ) . The primary outcome of this study was insulin resistance as measured by homeostasis model assessment ( HOMA-IR ) at 36 months . Fasting plasma insulin and glucose were examined as the secondary outcomes . RESULTS —The effect of 36-month vitamin K supplementation  on HOMA-IR differed by sex ( sex × treatment interaction P = 0.02 ) . HOMA-IR was statistically significantly lower at the 36-month visit among men in the supplement group versus the men in the control group ( P = 0.01 ) after adjustment for baseline HOMA-IR , BMI , and body weight change . There were no statistically significant differences in outcome measures between intervention groups in women . CONCLUSIONS —Vitamin K supplementation for 36 months at doses attainable in the diet may reduce progression of insulin resistance in older men Insufficient vitamin D status has been linked to autoimmune diseases , cancer and metabolic disorders , like obesity and insulin resistance . In vitro and animal studies suggest that vitamin D may play a crucial role in immune activation and inflammation . The relation between vitamin D and pro-inflammatory cytokines is not completely established . Furthermore , it is not known if the effect of vitamin D on entities of metabolic syndrome is mediated through its effect on cytokines or other biomarkers . The objectives of this study were to investigate if there is a relationship between vitamin D status and such pro-inflammatory cytokines as tumor necrosis factor-alpha ( TNF-α ) , interleukin 6 ( IL-6 ) and high sensitive C-reactive protein ( hs-CRP ) in patients with overweigh and obesity . We also proposed that the intervention with high dose of cholecalciferol may have effect on the cytokine levels and result in corresponding changes in the measures of insulin resistance ( HOMA-IR and QUICKI ) . Serum levels of IL-6 , TNF-α and hs-CRP were measured in 332 overweight and obese subjects who completed a 1-year r and omised intervention with either 40,000 IU vitamin D ( cholecalciferol ) per week or 20,000 IU vitamin D per week  ,  or placebo .  We found significant associations between IL-6 , TNF-α , vitamin D and insulin resistance indices at baseline . One year intervention with vitamin D  decreased serum IL-6 levels ; however hs-CRP levels were significantly increased . Neither measures of insulin resistance , nor TNF-α were influenced by a 1-year vitamin D supplementation Low serum 25-hydroxyvitamin D ( 25(OH)D ) has been shown to correlate with increased risk of type 2 diabetes . Small , observational studies suggest an action for vitamin D in improving insulin sensitivity and /or insulin secretion . The objective of the present study was to investigate the effect of improved vitamin D status on insulin resistance ( IR ) , utilising r and omised , controlled , double-blind intervention administering 100 microg ( 4000 IU ) vitamin D(3 ) ( n 42 ) or placebo ( n 39 ) daily for 6 months to South Asian women , aged 23 - 68 years , living in Auckl and , New Zeal and . Subjects were insulin resistant - homeostasis model assessment 1 (HOMA1)>1.93 and had serum 25(OH)D concentration < 50 nmol/l . Exclusion criteria included diabetes medication and vitamin D supplementation > 25 microg ( 1000 IU)/d . The HOMA2 computer model was used to calculate outcomes . Median ( 25th , 75th percentiles ) serum 25(OH)D(3 ) increased significantly from 21 ( 11 , 40 ) to 75 ( 55 , 84 ) nmol/l with supplementation . Significant improvements were seen in insulin sensitivity and IR ( P = 0.003 and 0.02 , respectively ) , and fasting insulin decreased ( P = 0.02 ) with supplementation compared with placebo . There was no change in C-peptide with supplementation . IR was most improved when endpoint serum 25(OH)D reached > or = 80 nmol/l . Secondary outcome variables ( lipid profile and high sensitivity C-reactive protein ) were not affected by supplementation . In conclusion , improving vitamin D status in insulin resistant women result ed in improved IR and sensitivity , but no change in insulin secretion . Optimal vitamin D concentrations for reducing IR were shown to be 80 - 119 nmol/l , providing further evidence for an increase in the recommended adequate levels . Registered Trial No. ACTRN12607000642482 Insulin resistance is one of the most common features of polycystic ovary syndrome ( PCOS ) . Some studies suggest that vitamin D deficiency may have a role in insulin resistance ; thus , the aim of the current study was to determine the effect of vitamin D supplementation on insulin resistance in women with PCOS and a vitamin D deficiency . We hypothesized that vitamin D supplementation would lower the glucose level and insulin resistance in women with PCOS and a vitamin D deficiency . The current study was a r and omized , placebo-controlled , double-blinded trial with 50 women with PCOS and a vitamin D deficiency , 20 to 40 years old , assigned to receive 3 oral treatments consisting of 50,000 IU of vitamin D₃ or a placebo ( 1 every 20 days ) for 2 months ( vitamin D , n = 24 ; placebo , n = 26 ) . The fasting blood glucose , insulin , 25-hydroxyvitamin D , and parathyroid hormone levels , as well as the homeostasis model assessment of insulin resistance and quantitative insulin sensitivity check index were measured at baseline and after treatment . In the vitamin D group , the serum level of 25-hydroxyvitamin D increased ( 6.9 ± 2.8 to 23.4 ± 6.1 ng/mL , P < .0001 ) , and the parathyroid hormone level decreased ( 70.02 ± 43.04 to 50.33 ± 21.99 μ IU/mL , P = .02 ) . There were no significant changes in the placebo group . There was a significant increase in insulin secretion in the vitamin D group ( P = .01 ) , but this was not significant compared with the placebo group . The fasting serum insulin and glucose levels and the insulin sensitivity and homeostasis model assessment of insulin resistance did not change significantly by the end of the study . We were not able to demonstrate the effect of vitamin D supplementation on insulin sensitivity and insulin resistance in women with PCOS and vitamin D deficiency OBJECTIVE To compare the effects of short-term dietary supplementation with tomato juice , vitamin E , and vitamin C on susceptibility of LDL to oxidation and circulating levels of C-reactive protein ( C-RP ) and cell adhesion molecules in patients with type 2 diabetes . RESEARCH DESIGN AND METHODS There were 57 patients with well-controlled type 2 diabetes aged < 75 years treated with placebo for 4 weeks and then r and omized to receive tomato juice ( 500 ml/day ) , vitamin E ( 800 U/day ) , vitamin C ( 500 mg/day ) , or continued placebo treatment for 4 weeks . Susceptibility of LDL to oxidation ( lag time ) and plasma concentrations of lycopene , vitamin E , vitamin C , C-RP , vascular cell adhesion molecule 1 , and intercellular adhesion molecule 1 were measured at the beginning of the study , after the placebo phase , and at the end of the study . RESULTS Plasma lycopene levels increased nearly 3-fold ( P = 0.001 ) , and the lag time in isolated LDL oxidation by copper ions increased by 42 % ( P = 0.001 ) in patients during supplementation with tomato juice . The magnitude of this increase in lag time was comparable with the corresponding increase during supplementation with vitamin E ( 54 % ) . Plasma C-RP levels decreased significantly ( -49 % , P = 0.004 ) in patients who received vitamin E.  Circulating levels of cell adhesion molecules and plasma glucose did not change significantly during the study . CONCLUSIONS This study indicates that consumption of commercial tomato juice increases plasma lycopene levels and the intrinsic resistance of LDL to oxidation almost as effectively as supplementation with a high dose of vitamin E , which also decreases plasma levels of C-RP , a risk factor for myocardial infa rct ion , in patients with diabetes . These findings may be relevant to strategies aim ed at reducing risk of myocardial infa rct ion in patients with diabetes Background : Vitamin D supplementation has been proposed as a potential strategy to prevent  type 2 diabetes .  Existing clinical trials have been limited by short duration , low doses of vitamin D , variability in participants ' vitamin D-deficiency status , and the use of surrogate measures of body composition , insulin sensitivity , and insulin secretion . Objective : To address existing knowledge gaps , we conducted a double-blind , r and omized , placebo-controlled trial to investigate whether vitamin D supplementation that is provided in a sufficient dose and duration to vitamin D-deficient individuals would improve insulin sensitivity or secretion as measured with the use of gold-st and ard methods . We hypothesized that vitamin D supplementation would improve insulin sensitivity and secretion compared with placebo . Design : Sixty-five overweight or obese , vitamin D-deficient ( 25-hydroxyvitamin D [ 25(OH)D ] concentration ≤50 nmol/L ) adults were r and omly assigned to receive either a bolus oral dose of 100,000 IU cholecalciferol followed by 4000 IU cholecalciferol/d or a matching placebo for 16 wk . Before and after the intervention , participants received gold-st and ard assessment s of body composition ( via dual X-ray absorptiometry ) , insulin sensitivity ( via hyperinsulinemic-euglycemic clamps ) , and insulin secretion [ via intravenous-glucose-tolerance tests ( IVGTTs ) ] . Results : Fifty-four participants completed the study [ 35 men and 19 women ; mean ± SD age : 31.9 ± 8.5 y ; body mass index ( in kg/m2 ) : 30.9 ± 4.4 ] . 25(OH)D increased with vitamin D supplementation compared with placebo ( 57.0 ± 21.3 compared with 1.9 ± 15.1 nmol/L , respectively ; P = 0.02 ) . Vitamin D and placebo groups did not differ in change in insulin sensitivity ( 0.02 ± 2.0 compared with -0.03 ± 2.8 mg · kg-1 · min-1 , respectively ; P = 0.9 ) or first-phase insulin secretion ( -21 ± 212 compared with 24 ± 184 mU/L , respectively ; P = 0.9 ) . Results remained nonsignificant after adjustment for age , sex , percentage of body fat , sun exposure , physical activity , and dietary vitamin D intake ( P > 0.1 ) . Conclusions : Vitamin D supplementation does not improve insulin sensitivity or secretion in vitamin D-deficient , overweight or obese adults , despite using high-dose vitamin D supplementation and robust endpoint measures . Therefore , it is unlikely that vitamin D supplementation would be an effective strategy for reducing diabetes risk even in vitamin D-deficient population s. This trial was registered at clinical trials.gov as NCT02112721 Background Despite Australia ’s sunny climate , low vitamin D levels are increasingly prevalent . Sun exposure is limited by long working hours , an increase in time spent indoors , and sun protection practice s , and there is limited dietary vitamin D fortification . While the importance of vitamin D for bone mineralization is well known , its role as a protective agent against chronic diseases , such as type 2 diabetes and cardiovascular disease , is less understood . Observational and limited intervention studies suggest that vitamin D might improve insulin sensitivity and secretion , mainly via its anti-inflammatory properties , thereby decreasing the risk of development and progression of type 2 diabetes . The primary aim of this trial is to investigate whether improved plasma concentrations of 25-hydroxyvitamin D ( 25(OH)D ) , obtained through vitamin D supplementation , will increase insulin sensitivity and insulin secretion . A secondary aim is to determine whether these relationships are mediated by a reduction in underlying sub clinical inflammation associated with obesity . Methods / Design Fifty overweight but otherwise healthy nondiabetic adults between 18 and 60 years old , with low vitamin D levels ( 25(OH)D < 50 nmol/l ) , will be r and omly assigned to intervention or placebo . At baseline , participants will undergo a medical review and anthropometric measurements , including dual X-ray absorptiometry , an intravenous glucose tolerance test , muscle and fat biopsies , a hyperinsulinemic euglycemic clamp  , and question naires assessing diet , physical activity , sun exposure , back and knee pain , and depression . The intervention group will receive a first dose of 100,000 IU followed by 4,000 IU vitamin D ( cholecalciferol ) daily , while the placebo group will receive apparently identical capsules , both for a period of 16 weeks . All measurements will be repeated at follow-up , with the primary outcome measure expressed as a change from baseline in insulin sensitivity and secretion for the intervention group compared with the placebo group . Secondary outcome measures will compare changes in anthropometry , cardiovascular risk factors , and inflammatory markers . Discussion The trial will provide much needed clinical evidence on the impact of vitamin D supplementation on insulin resistance and secretion and its underlying mechanisms , which are relevant for the prevention and management of type 2 diabetes . Trial registration Clinical trials.gov ID : NCT02112721 Background Hypovitaminosis D has been associated with the development of gestational diabetes mellitus ( GDM ) in many observational studies . Objectives We report the first study of the impact of prenatal vitamin D supplementation on postpartum dysglycemia in GDM patients in a r and omized clinical trial . Patients and Methods Women with GDM at 12 - 32 weeks of gestation were assigned r and omly to either the intervention group ( in which serum 25-hydroxy vitamin D [ 25OHD ] levels were measured immediately , n = 48 ) or the control group ( in which the serum was stored and assayed at 6 - 12 weeks post-partum , n = 48 ) . Participants with initial serum 25OHD < 30 ng/mL in the intervention group were instructed to take a total of 700,000 IU vitamin D3 during pregnancy . The primary outcomes were fasting plasma glucose ( FPG ) , insulin , 2-h post 75 g glucose load plasma glucose ( 2-hPLG ) , homeostasis model assessment of insulin resistance ( HOMA-IR ) , HbA1C , and 25 OHD at 6 - 12 weeks after delivery . Results The mean ± SD of serum 25OHD in the intervention group raised dramatically from 14.6 ± 6.3 to 32.4 ± 14.4 ng/mL , whereas no significant change occurred in the control group ( from 17.7 ± 6.1 to 19.3 ± 9.6 ng/mL , P < 0.001 ) . Thirteen participants developed dysglycemia in each group . Mean FPG , 2-hPLG , and HOMA-IR were not significantly different between the groups . There was no significant difference between the groups for maternal and neonatal outcomes . Conclusions Although the high vitamin D supplementation dose in the present study ( compared to the 400 IU/day dose usually recommended for pregnancy ) safely increases the serum 25OHD , in GDM cases , the higher dose does not affect the plasma glucose level or insulin resistance at short term follow-up after delivery BACKGROUND A suboptimal vitamin D and calcium status has been associated with higher risk of type 2 diabetes in observational studies , but evidence from trials is lacking . OBJECTIVE We determined whether vitamin D supplementation , with or without calcium , improved glucose homeostasis in adults at high risk of diabetes . DESIGN Ninety-two adults were r and omly assigned in a 2-by-2 factorial- design , double-masked , placebo-controlled trial to receive either cholecalciferol ( 2000 IU once daily ) or calcium carbonate ( 400 mg twice daily ) for 16 wk . The primary outcome was the change in pancreatic β cell function as measured by the disposition index after an intravenous-glucose-tolerance test . Other outcomes were acute insulin response , insulin sensitivity , and measures of glycemia . RESULTS Participants had a mean age of 57 y , a body mass index ( BMI ; in kg/m(2 ) ) of 32 , and glycated hemoglobin ( Hb A(1c ) ) of 5.9 % . There was no significant vitamin D × calcium interaction on any outcomes . The disposition index increased in the vitamin D group and decreased in the no-vitamin D group ( adjusted mean change ± SE : 300 ± 130 compared with -126 ± 127 , respectively ; P = 0.011 ) , which was explained by an improvement in insulin secretion ( 62 ± 39 compared with -36 ± 37 mU · L(-1 ) · min , respectively ; P = 0.046 ) . Hb A(1c ) increased less , but nonsignificantly , in the vitamin D group than in the no-vitamin D group ( 0.06 ± 0.03 % compared with 0.14 ± 0.03 % , respectively ; P = 0.081 ) . There was no significant difference in any outcomes with calcium compared with no calcium . CONCLUSION In adults at risk of type 2 diabetes , short-term supplementation with cholecalciferol improved β cell function and had a marginal effect on attenuating the rise in Hb A(1c ) . This trial was registered at clinical trials.gov as NCT00436475 It has previously been reported that the influence of vitamin D on the metabolism of calcium and phosphorus is associated with diabetes , cardiovascular disease , Alzheimer 's disease , cancer and other systemic diseases , and is considered an important indicator of general health . The present study was conducted to determine the effect of various doses of vitamin D supplementation on glucose metabolism , lipid concentrations , inflammation and the levels of oxidative stress of pregnant women with gestational diabetes mellitus ( GDM ) . The present r and omized , double-blind placebo-controlled clinical trial was conducted on 133 pregnant women with GDM during weeks 24 - 28 of pregnancy . The patients were r and omly divided into four groups . The control group ( n=20 ) received a placebo ( sucrose ; one granule/day ) , the low dosage group ( n=38 ) received the daily recommended intake of 200 IU vitamin D ( calciferol ) daily , the medium dosage group ( n=38 ) received 50,000 IU monthly ( 2,000 IU daily for 25 days ) and the high dosage group ( n=37 ) received 50,000 IU every 2 weeks ( 4,000 IU daily for 12.5 days ) . The general characteristics and dietary intakes of the patients with GDM were similar between each group . Using ELISA kits , it was determined that insulin , homeostatic model assessment -insulin resistance and total cholesterol were significantly reduced by high dosage vitamin D supplementation ( P<0.05 ) . Total antioxidant capacity and total glutathione levels were significantly elevated as a result of high dosage vitamin D supplementation ( P<0.01 ) . In conclusion , high-dose vitamin D supplementation ( 50,000 IU every 2 weeks ) significantly improved insulin resistance in pregnant women with GDM BACKGROUND Low serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations have been associated with insulin resistance , the metabolic syndrome , and type 2 diabetes . Because many non-Western immigrants in the Netherl and s are vitamin D deficient , obese , and at high risk of diabetes , vitamin D supplementation may contribute to prevent diabetes and insulin resistance . OBJECTIVE We examined the effect of vitamin D supplementation on insulin sensitivity and β cell function in overweight , vitamin D-deficient , non-Western immigrants at high risk of diabetes . DESIGN The study was a 16-wk , r and omized , placebo-controlled trial . A total of 130 non-Western immigrants with prediabetes ( fasting glucose concentration > 5.5 mmol/L or r and om glucose concentration from 7.8 to 11.1 mmol/L ) and vitamin D deficiency ( serum 25[OH]D concentration < 50 nmol/L ) were r and omly assigned after stratification by sex to receive either cholecalciferol ( 1200 IU/d ) or a placebo for 16 wk . All participants received 500 mg Ca/d as calcium carbonate . The primary outcome was the difference in the area under the curve of insulin and glucose after a 75-g oral-glucose-tolerance test after 4 mo of treatment . Secondary outcomes were insulin-sensitivity variables , β cell-function variables , and metabolic syndrome . RESULTS Mean serum 25(OH)D concentrations increased significantly in the vitamin D compared with placebo groups . After 4 mo of therapy , the mean between-group difference was 38 nmol/L ( 95 % CI : 32.1 , 43.9 nmol/L ; P < 0.001 ) . There was no significant effect on insulin sensitivity and β cell function . In a post hoc analysis , when patients with diabetes at baseline were excluded , a significant increase in the insulinogenic index was observed in participants who obtained a 25(OH)D concentration ≥60 nmol/L ( P = 0.040 ) . CONCLUSIONS Vitamin D supplementation in non-Western vitamin D-deficient immigrants with prediabetes did not improve insulin sensitivity or β cell function or change the incidence of metabolic syndrome . However , after the exclusion of diabetic subjects , an improvement in the insulinogenic index was observed in participants who obtained a 25(OH)D concentration ≥60 nmol/L. This trial was registered at trialregister.nl as NTR1827 Questions have been raised about potentially negative effects of antenatal folic acid use in population s with a high prevalence of vitamin B-12 deficiency . Our objective was to examine the association between maternal folate and vitamin B-12 status in pregnancy on offspring insulin resistance  and examine whether the effects of maternal micronutrient supplementation varied by baseline maternal folate and /or vitamin B-12 status . Pregnant women were cluster r and omized to receive daily supplements containing vitamin A alone or with folic acid , folic acid+iron , folic acid+iron+zinc , or a multiple micronutrient .  In a sub sample ( n = 1132 ) , micronutrient status biomarkers were analyzed at baseline and late pregnancy . Children born to the women who participated in the trial were visited at 6 - 8 y of age . Fasting plasma glucose and insulin were used to estimate insulin resistance using the homeostasis model assessment ( HOMA-IR ) . Children whose mothers were deficient in vitamin B-12 ( < 148 pmol/L , 27 % ) during early pregnancy had a 26.7 % increase in HOMA-IR ( P = 0.02 ) , but there was no association with maternal folate status . Among children born to women who were vitamin B-12 deficient at baseline , the percent difference in HOMA-IR compared to the control group was 15.1 % ( 95 % CI : -35.9 , 106.4 ) , 4.9 % ( -41.6 , 88.5 ) , 3.3 % ( -38.4 , 73.5 ) , and 18.1 % ( -29.0 , 96.7 ) in the folic acid , folic acid-iron , folic acid-iron-zinc , and multiple micronutrient supplementation groups , respectively , none of which were significant . Maternal vitamin B-12 deficiency is associated with an elevated risk of insulin resistance , but supplementation with folic acid or other micronutrients led to no significant change in insulin resistance in school-aged offspring Background Besides the classical role of vitamin D on calcium and bone homeostasis , vitamin D deficiency has recently been identified as a contributing factor in the onset of insulin resistance in type 2 diabetes mellitus . However , it is uncertain whether vitamin D deficiency and poor glycaemic control are causally interrelated or that they constitute two independent features of type 2 diabetes mellitus . There are limited clinical trials carried out which measured the effect of vitamin D supplementation on glycaemic control . The objective of this study is to investigate the effect of vitamin D supplementation on glycaemic control and quality of life in patients with type 2 diabetes mellitus . Methods / design In a r and omised double-blind placebo-controlled trial conducted in five general practice s in the Netherl and s three hundred patients with type 2 diabetes mellitus treated with lifestyle advises or metformin or sulphonylurea-derivatives are r and omised to receive either placebo or 50,000 IU Vitamin D3 at monthly intervals . The primary outcome measure is the change in glycated haemoglobin level between baseline and six months . Secondary outcome measures include blood pressure , anthropometric parameters , lipid profile , insulin resistance , quality of life , advanced glycation end products and safety profiles . Quality of life will be measured by The Short Form ( SF-36 ) Health Survey question naire . Advanced glycation end products are measured by an AGE-reader . Discussion This trial will be the first study exploring the effect of vitamin D supplementation on both glycaemic control and quality of life in patients with type 2 diabetes mellitus . Our findings will contribute to the knowledge of the relationship between vitamin D status and insulin resistance in patients with type 2 diabetes mellitus . Trial registration The Netherl and s trial register : The aim was to assess the effects of resistance training and vitamin D supplementation on physical performance of healthy elderly subjects . Ninety-six subjects , aged 70 years or more with 25 OH vitamin D levels of 16 ng/ml or less , were r and omized to a  resistance training or control group . Trained and control groups were further r and omized to receive in a double blind fashion , vitamin D 400 IU plus 800 mg of calcium per day or calcium alone . Subjects were followed for nine months . Serum 25 OH vitamin D increased from 12.4+/-2.2 to 25.8+/-6.5 ng/ml among subjects supplemented with vitamin D. Trained subjects had significant improvements in quadriceps muscle strength , the short physical performance test and timed up and go . The latter improved more in trained subjects supplemented with vitamin D. At the end of the follow up , gait speed was higher among subjects supplemented with vitamin ( whether trained or not ) than in non-supplemented subjects ( 838+/-147 and 768+/-127 m/12 min , respectively , p=0.02 ) . Romberg ratio was lower among supplemented controls than non-supplemented trained subjects ( 128+/-40 % and 144+/-37 % , respectively , p=0.05 ) . In conclusion , vitamin D supplementation improved gait speed and body sway , and training improved muscle strength Background / Aims Recent epidemiological studies revealed a striking inverse relationship between vitamin D levels , glucose intolerance/insulin resistance ( IR ) , and cardiovascular disease . However , few interventional studies have evaluated the effect of vitamin D supplementation on cardiovascular risk , such as IR and arterial stiffness , in diabetes . We investigated the role of vitamin D supplementation on cardiovascular risk in type 2 diabetes patients , including metabolic parameters , IR , and arterial stiffness . Methods We enrolled patients who were taking antidiabetic medications or managed their diabetes using lifestyle changes . We excluded patients who were taking vitamin D or calcium supplements .  We r and omized participants into the vitamin D group ( cholecalciferol 2,000 IU/day + calcium 200 mg/day , n = 40 ) or the placebo group ( calcium 200 mg/day , n = 41 ) . We compared their IR ( homeostasis model of assessment [HOMA]-IR ) and arterial stiffness ( brachial-ankle pulse wave velocity and radial augmentation index ) before and after 24 weeks of intervention . Results The baseline characteristics of the two groups were similar . A total of 62 participants ( placebo , 30 ; vitamin D , 32 ) completed the study protocol . At the end of the study period , the 25-hydroxyvitamin D [ 25(OH)D ] levels were significantly higher in the vitamin D group than in the placebo group ( 35.4 ± 8.5 ng/mL vs. 18.4 ± 7.3 ng/mL , p < 0.001 ) . There was no difference in HOMA-IR or changes in arterial stiffness  ( placebo , 21 , vitamin D , 24 ) between the groups . Conclusions Our data suggest that high-dose vitamin D supplementation might be effective in terms of elevating 25(OH)D levels . However , we identified no beneficial effects on cardiovascular risk in type 2 diabetes , including IR and arterial stiffness OBJECTIVE To determine whether supplementation with vitamins and trace elements in modest amounts influences cognitive function in apparently healthy , elderly subjects . METHODS The study was design ed as a r and omized , double-blind , placebo-controlled trial . Ninety-six , apparently healthy , independent men and women older than 65 y of age were recruited and r and omized to receive a supplement of trace elements and vitamins or a placebo daily for 12 mo . Blood-nutrient levels were estimated at baseline and at the end of the study . The major outcome measure assessed was cognitive function consisting of immediate and long-term memory , abstract thinking , problem-solving ability , and attention . RESULTS Eighty-six subjects completed the 1-y trial . The supplemented group showed a significant improvement in all cognitive tests ( P < 0.001 to 0.05 ) except long-term memory recall ( P > 0.1 ) . Those whose blood-nutrient levels were below the reference st and ard showed lower responses on cognitive tests . There was no significant correlation between individual nutrient levels and performance on various cognitive function tests . CONCLUSIONS Cognitive functions improved after oral supplementation with modest amounts of vitamins and trace elements . This has considerable clinical and public health significance . We recommend that such a supplement be provided to all elderly subjects because it should significantly improve cognition and thus quality of life and the ability to perform activities of daily living . Such a nutritional approach may delay the onset of Alzheimer 's disease Abstract Limited data are available assessing the effects of vitamin D and evening primrose oil ( EPO ) administration on markers of insulin resistance and lipid concentrations in gestational diabetes mellitus ( GDM ) . This study was design ed to evaluate the effects of vitamin D and EPO administration on insulin resistance and lipid concentrations among women with GDM . In this prospect i ve r and omized , double-blind , placebo-controlled clinical trial , 60 participants with GDM were divided into 2 groups of either 1000 IU vitamin D3 and 1000 mg EPO or placebo for 6 weeks . At the beginning and end of the study , fasting blood sample s were obtained from the participants to measure related variables . After 6 weeks of intervention , changes in fasting plasma glucose ( −3.6 ± 7.5 vs. + 1.5 ± 11.4 mg/dL , P = 0.04 ) , serum insulin concentrations ( −2.0 ± 5.3 vs. + 4.6 ± 10.7 µIU/mL , P = 0.004 ) , homeostasis model of assessment ( HOMA ) insulin resistance ( −0.5 ± 1.1 vs. + 1.1 ± 2.5 , P = 0.003 ) , HOMA-B cell function ( −7.7 ± 23.3 vs. + 17.4 ± 42.9 , P = 0.007 ) and the quantitative insulin sensitivity check index ( + 0.01 ± 0.02 vs. −0.01 ± 0.02 , P = 0.007 ) in the vitamin D plus EPO group were significantly different from the placebo group . In addition , compared with the placebo , vitamin D and EPO supplementation result ed in significant reductions in serum TAG ( −20.0 ± 54.3 vs. + 34.3 ± 38.2 mg/dL , P < 0.001 ) , VLDL ( −4.0 ± 10.9 vs. + 6.9 ± 7.6 mg/dL , P < 0.001 ) , TC ( −22.1 ± 32.6 vs. + 5.3 ± 20.1 mg/dL , P < 0.001 ) , LDL concentrations ( −18.0 ± 25.5 vs. + 1.8 ± 15.7 mg/dL , P = 0.001 ) and TC/HDL ( −0.3 ± 0.4 vs. + 0.3 ± 0.5 mg/dL , P < 0.001 ) . We did not observe any significant effect of vitamin D and EPO supplementation on serum HDL concentrations . Clinical trial registration number : http://www.i rct .ir : I RCT 201509115623N52 Both altered GH-IGF-I axis and low serum levels of 25-hydroxyvitamin D ( 25(OH)D ) are linked to measures of metabolic syndrome . Our hypothesis was that there is a relation between GH , IGF-I , and 25(OH)D ; and that vitamin D supplementation may have an effect on the levels of GH , IGF-I , and IGF-I/IGFBP-3 ratio . 318 overweight and obese subjects completed a one-year r and omized intervention with either 40,000 or 20,000 IU cholecalciferol per week or placebo .  GH , IGF-I , IGFBP-3 and measures of insulin resistance were evaluated at baseline and at the end of study . There was a significant relation between entities of GH-IGF-I axis and insulin resistance .  Subjects with severe obesity had significantly lower serum 25(OH)D and had a significant linear decline in IGF-I/IGFBP-3 ratio with increasing serum 25(OH)D quartiles . Vitamin D status was an independent predictor of GH-IGF-I axis and supplementation with vitamin D decreased IGF-I/IGFBP-3 ratio in subjects without severe obesity . No corresponding effect of vitamin D supplementation on BMI or insulin resistance was observed . Adverse effects of GH-IGF-I axis on glucose metabolism and the development of metabolic syndrome may be in part associated with the changes in vitamin D status
Conclusions Short-term ( 4–12 weeks ) supplementation with vitamin D is associated with lower fasting glucose levels in ESRD with no change in fasting insulin levels .
Abstract Purpose We tested whether short-term vitamin D supplementation improves insulin resistance in patients with kidney disease , a condition with little intrinsic vitamin D activity .