Evidence from trials with vitamin D and /or calcium supplementation suggests that combined vitamin D and calcium supplementation may have a role in the prevention of type 2 DM only in population s at high risk ( i.e. glucose intolerance ) .
Vitamin D and calcium insufficiency may negatively influence glycemia , whereas combined supplementation with both nutrients may be beneficial in optimizing glucose metabolism
CONTEXT Altered vitamin D and calcium homeostasis may play a role in the development of type 2 diabetes mellitus ( type 2 DM ) .
Vitamin D Status and Glucose Homeostasis in the 1958 British Birth Cohort
OBJECTIVE —Obesity is a well-known risk factor for vitamin D deficiency . We evaluated the interrelationship between vitamin D status , body size , and glucose homeostasis , measured by HbA1c ( A1C ) . RESEARCH DESIGN AND METHODS — Data are from the survey of the 45-year-old 1958 British birth cohort ( 2002–2004 ) . Information on A1C , 25-hydroxyvitamin D [ 25(OH)D ;  an indicator of  vitamin D status ] , and BMI was collected from 7,198 Caucasian subjects . RESULTS —25(OH)D was < 75 nmol/l in 80 % of the obese subjects ( BMI ≥30 kg/m2 ) versus 68 % of the other subjects ( P < 0.0001 ) . Serum 25(OH)D decreased and A1C increased by increasing BMI ( P < 0.0001 for both comparisons ) . There was a nonlinear association between 25(OH)D and A1C : a steep linear decrease in A1C by 25(OH)D until 65 nmol/l and only smaller decreases with further increases . There was evidence for effect modification by BMI in the association between 25(OH)D and A1C ( P < 0.0001 ) , and differences appeared stronger for participants with higher compared with lower BMI s. After adjustment for sex , season , geographical location , physical activity , and social class , percent change in A1C by 10-nmol/l increase in 25(OH)D was −0.21 ( 95 % CI −0.31 to −0.11 ) for BMI < 25 kg/m2 , −0.25 ( −0.37 to −0.13 ) for BMI 25–29.9 kg/m2 , −0.65 ( −0.95 to −0.34 ) for BMI 30–34.9 kg/m2 , and −1.37 ( −2.09 to −0.64 ) for BMI ≥35 kg/m2 . CONCLUSIONS —Body size was a strong determinant for 25(OH)D , with concentrations being suboptimal in most obese participants . R and omized controlled trials [ using dosages sufficient to improve 25(OH)D also for the obese ] are required to determine whether clinical ly relevant improvements in glucose metabolism can be obtained by vitamin D supplementation
Evidence from trials with vitamin D and /or calcium supplementation suggests that combined vitamin D and calcium supplementation may have a role in the prevention of type 2 DM only in population s at high risk ( i.e. glucose intolerance ) .
Vitamin D and calcium insufficiency may negatively influence glycemia , whereas combined supplementation with both nutrients may be beneficial in optimizing glucose metabolism
CONTEXT Altered vitamin D and calcium homeostasis may play a role in the development of type 2 diabetes mellitus ( type 2 DM ) .