The effect of vitamin D supplementation on the glycemic control of pre-diabetic Qatari patients in a randomized control trial

Abstract

Background: Vitamin D deficiency is associated with indicators of pre-diabetes including, insulin resistance, β-cell dysfunction and elevated plasma glucose with controversial findings from current trials. This study aims to investigate the long-term effect of vitamin D on glucose metabolism and insulin sensitivity in pre-diabetic and highly vitamindeficient subjects. Methods: One hundred thirty-two participants were randomized to 30,000 IU vitamin D weekly for 6 months. Participants underwent oral glucose tolerance test (OGTT) at 3-month intervals to determine the change in plasma glucose concentration at 2 h after 75 g OGTT (2hPCG). Secondary measurements included glycated hemoglobin, fasting plasma glucose and insulin, post-prandial insulin, indices of insulin sensitivity (HOMA-IR, Matsuda Index), β-cell function (HOMA-β, glucose and insulin area under the curve (AUC), disposition and insulinogenic indices), and lipid profile. Results: A total of 57 (vitamin D) and 75 (placebo) subjects completed the study. Mean baseline serum 25(OH) D levels were 17.0 ng/ml and 14.9 ng/ml for placebo and vitamin D group, respectively. No significant differences were observed for 2hPC glucose or insulin sensitivity indices between groups. HOMA-β significantly decreased in the vitamin D group, while area under curve for glucose and insulin showed a significant reduction in β-cell function in both groups. Additionally, HOMA-β was found to be significantly different between control and treatment group and significance persisted after adjusting for confounding factors. Conclusion: Vitamin D supplementation in a pre-diabetic and severely vitamin-deficient population had no effect on glucose tolerance or insulin sensitivity. The observed reduction in β-cell function in both placebo and vitamin D groups could be attributed to factors other than supplementation. Trial registration: NCT02098980, 28/03/2014 (www.clinicaltrials.gov).

Type 2 diabetes is more predictable in women than men by multiple anthropometric and biochemical measures

“…The discrepancy could be due to the cohort difference, including age, ethnicity, and eating habit. However, our results are in line with the failure in clinical trials of vitamin D supplements for improving glucose tolerance and insulin sensitivity 36 . By analyzing multiple anthropometric and biochemical measures, we rank them by their ability to predict T2D according to the ROC-AUC values: in women, age (0.75) > waist circumference (0.70) > systolic pressure (0.66) = triglyceride (0.66) = fasting proinsulin (0.66) > fasting insulin (0.64) > total cholesterol (0.63) > BMI (0.62) = LDL (0.62) > LDL (0.62) > diastolic pressure (0.60); in men, age (0.69) > fasting proinsulin (0.62) > fasting P/I ratio (0.61).…”

“…The discrepancy could be due to the cohort difference, including age, ethnicity, and eating habit. However, our results are in line with the failure in clinical trials of vitamin D supplements for improving glucose tolerance and insulin sensitivity 36 .…”

A Community Based Randomized Controlled Trial to See the Effect of Vitamin D Supplementation on Development of Diabetes Among Women with Prediabetes Residing in A Rural Community of Northern India

“…[ 21 ] In another study conducted by Harris et al .,[ 22 ] it was observed that Insulin sensitivity decreased by 4% in the intervention (Vit D group) while it increased by 12% in the control group ( P = 0.034). Whereas in other studies[ 23 24 25 26 ] there was no significant effect of vitamin D on insulin sensitivity.…”

Effect of Vitamin D Supplementation on Glycemic Control in Prediabetes: A Meta-Analysis

“…The change in BMI after vitamin D intervention was reported in 23 studies (N = 2854) [12,14,17,18,[20][21][22][23][25][26][27][28][29][30][31][32][33][34][35][36][37]39,40]. Random-effects meta-analysis showed no difference in BMI changes between vitamin D supplementation and controls (SMD = 0.01; 95%CI: −0.22, 0.24; p = 0.935) (Figure S2), while the results showed statistically significant heterogeneity (I 2 = 88.7%, p < 0.001).…”

“…Twenty-five trials involving 3144 participants were included to demonstrate the effect of vitamin D supplementation on FBG in prediabetics [12][13][14][15][16][17][18][19][20][21]23,26,27,[29][30][31][32][33][34][35][36][37][38][39][40]. Overall, a significant decrease in FBG content was observed in the vitamin D supplementation group (SMD = −0.38; 95%CI: −0.59, −0.16; p = 0.001) (Figure 2), with a high heterogeneity (I 2 = 87.6%, p < 0.001).…”