This meta- analysis concludes that hypovitaminosis D is associated with increased risk of hyperglycemia both in diabetic and non-diabetic subjects .
There is evidence that vitamin D status is associated with type 2 diabetes .
Many observational studies have been performed investigating the relationship of vitamin D status and circulating biomarkers of glycemic regulation .
To find out whether this association holds , we conducted a systematic review and meta- analysis of cross sectional and longitudinal studies .
Serum vitamin-D predicts insulin resistance in individuals with prediabetes
Background & objectives : Patients with diabetes and vitamin-D insufficiency have increased insulin resistance . Similar observations among individuals with prediabetes are not well documented . The aim of this study was to find the occurrence of vitamin-D insufficiency/deficiency among individuals with prediabetes and to evaluate the relationship between vitamin-D status and insulin resistance . Methods : One hundred fifty seven individuals with prediabetes who fulfilled all the inclusion and exclusion criteria underwent clinical examination , anthropometric measurements ( waist circumference , waist-hip ratio , waist-height ratio ) and blood sampling after overnight fast for estimation of fasting blood glucose , fasting insulin , 25(OH)vitamin-D , intact parathyroid hormone ( iPTH ) and lipid profile . One hour post 75 g glucose ( 1hPG ) blood glucose during oral glucose tolerance test was measured . Results : Vitamin-D deficiency/insufficiency was found in 115 ( 73.25 % ) individuals with prediabetes .  Severe vitamin-D deficiency ( < 10 ng/ml ) was seen in 14.65 per cent individuals . Individuals with the lowest vitamin-D levels ( < 10 ng/ml ) had the highest insulin resistance ( HOMA2-IR : 2.04 ± 0.67 ) . Serum 25(OH)D had a statistically significant inverse correlation with insulin resistance ( HOMA2-IR ; r=-0.33 ; P=0.008 ) , and positive correlation with insulin sensitivity ( QUICKI ; r=0.39 ; P=0.002 ) , after adjusting for BMI and HbA1c . There was no correlation between vitamin-D status and estimated beta cell mass ( HOMA-β ) . The mean waist-height ratio among individuals with prediabetes was 0.57 ( normal<0.5 ) indicating a high risk of cardiovascular morbidity . Individuals with elevated 1hPG>155 mg/dl had significantly higher BMI and worse insulin resistance , and 1hPG correlated well with 2 hour post glucose blood glucose ( r=0.57 ; P<0.001 ) . Interpretations & conclusions : Vitamin-D deficiency/insufficiency may have some role in the development/worsening of insulin resistance in individuals with prediabetes in our country who have a high cardiovascular risk . Prospect i ve studies on a large group of individuals need to be done to confirm the findings
This meta- analysis concludes that hypovitaminosis D is associated with increased risk of hyperglycemia both in diabetic and non-diabetic subjects .
There is evidence that vitamin D status is associated with type 2 diabetes .
Many observational studies have been performed investigating the relationship of vitamin D status and circulating biomarkers of glycemic regulation .
To find out whether this association holds , we conducted a systematic review and meta- analysis of cross sectional and longitudinal studies .