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 vitamin D on insulin resistance and anthropometric parameters in Type 2 diabetes; a randomized double-blind clinical trial Lack of effect of subtherapeutic vitamin D treatment on glycemic and lipid parameters in Type 2 diabetes: A pilot prospective randomized trial. Effect of high doses of vitamin D on arterial properties, adiponectin, leptin and glucose homeostasis in type 2 diabetic patients. The Effects of Vitamin D Supplementation on Glucose Control and Insulin Resistance in Patients with Diabetes Type 2: A Randomized Clinical Trial Study Effect of vitamin D supplementation on insulin kinetics and cardiovascular risk factors in polycystic ovarian syndrome: a pilot study Effect of vitamin D supplementation on glycemic control in patients with type 2 diabetes: a systematic review of interventional studies Effect of Vitamin D Supplementation on Glucose Control and Inflammatory Response in Type II Diabetes: A Double Blind, Randomized Clinical Trial Effects of a single post-partum injection of a high dose of vitamin D on glucose tolerance and insulin resistance in mothers with first-time gestational diabetes mellitus. The effects of vitamin D supplementation on adiponectin level and insulin resistance in first-degree relatives of subjects with type 2 diabetes: a randomized double-blinded controlled trial Vitamin D supplementation reduces insulin resistance in Japanese adults: a secondary analysis of a double-blind, randomized, placebo-controlled trial. Study of comparative effects of antioxidants on insulin sensitivity in type 2 diabetes mellitus. Serum vitamin-D predicts insulin resistance in individuals with prediabetes 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 Supplementation with cholecalciferol does not improve glycaemic control in diabetic subjects with normal serum 25-hydroxyvitamin D levels Impact of treatment with oral calcitriol on glucose indices in type 2 diabetes mellitus patients. The effects of vitamin D and omega-3 fatty acid co-supplementation on glycemic control and lipid concentrations in patients with gestational diabetes.
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 ) Background & the purpose of the study Prevalence of type 2 diabetes mellitus ( T2DM ) is increasing worldwide . To reduce its risk and progression , preventive strategies are needed . Vitamin supplementation such as vitamin D is one of the strategies . This study was design ed to investigate the effect of injection of vitamin D on insulin resistance and anthropometric parameters in T2DM . Methods This r and omized double-blind clinical trial was conducted with 42 diabetic patients in two groups ; intervention group with  single intramuscular injection of 300,000 International Unit ( IU ) of vitamin D3 and the placebo group . After recording demographic and anthropometric factors ( waist circumference , blood pressure and body mass index ) , fasting blood sample s was taken for measurement of blood glucose , 25-hydroxyvitamin D3 ( 25-OHD3 ) , insulin , glycosylated hemoglobin A1c ( HbA1c ) and estimation of Homeostasis Model Assessment Index ( HOMA ) in two times ; before study and after three months . Results Two groups had similar baseline characteristics ( each group = 21 subjects ) . Three months after vitamin D injection , HbA1c , anthropometric factors and HOMA index in intervention group stayed constant , however , serum 25- OHD3 was significantly increased ( p = 0.007 ) . Conclusion The present data is not convincing and further studies with large sample sizes are needed to show the definite effect of injection of vitamin D on control of diabetes and its risk BACKGROUND Epidemiological studies suggest a higher prevalence of metabolic syndrome and its components among individuals with vitamin D deficiency . The aim of the present study was to determine whether vitamin D treatment  improves glucose control and insulin sensitivity in Type 2 diabetes mellitus ( T2DM ) . METHODS Subjects with T2DM and serum 25-hydroxyvitamin D ( 25(OH)D ) concentrations < 25 ng/mL were r and omized to receive 400 IU ( Group 1 ) or 1200 IU ( Group 2 ) cholecalciferol for 4 months . Fasting plasma glucose , glycosylated hemoglobin ( HbA1c ) , Quantitative Insulin Sensitivity Check Index ( QUICKI ) , serum lipid levels and serum adiponectin were measured at baseline and at 4 months . RESULTS Mean 25(OH)D levels increased in both groups ( from 17.6±1.5 to 25.5±1.8 ng/mL in Group 1 and from 15.6±1.4 to 27.4±2.4 ng/mL in Group 2 ; P≤0.001 vs baseline for each group ) . No significant differences were noted in fasting plasma glucose , HbA1c , QUICKI , serum adiponectin , and lipid levels compared with baseline within groups or between the two groups . CONCLUSIONS In the present pilot study , conventional vitamin D treatment at a level improving , but not optimizing , serum 25(OH)D did not improve glycemia , insulin sensitivity , or lipid profile . However , diabetes and lipids were relatively well controlled at baseline . Future studies should be design ed to achieve optimal concentrations of serum 25(OH)D ( at least > 32 ng/mL ) and should include subjects showing more abnormal parameters of glycemia , lipid , and insulin sensitivity at baseline BACKGROUND & AIMS Vitamin D supplementation has the potential to alleviate the cardiovascular damage in diabetic patients . The present study was design ed to evaluate long term impact of high doses of vitamin D on arterial properties , glucose homeostasis , adiponectin and leptin in patients with type 2 diabetes mellitus . METHODS AND RESULTS In r and omized , placebo-controlled study 47 diabetic patients were assigned into two groups : Group 1 received oral daily supplementation with vitamin D at a dose of 1000 U/day for 12 months . Group 2 received matching placebo capsules . Blood sampling for metabolic parameters , including fasting glucose , lipid profile , HbA1C , insulin , hs-CRP , 25 OH Vit D , adiponectin and leptin was performed at baseline and at the end of the study . Insulin resistance was assessed by homeostasis model assessment ( HOMA-IR ) . Central aortic augmentation index ( AI ) was evaluated using SphygmoCor . RESULTS The two groups were similar at baseline in terms of hemodynamic parameters . After 12 months , AI decreased significantly during the treatment period in patients received vitamin D ( p < 0.0001 ) and did not change in placebo group . Glucose homeostasis parameters , leptin as well as leptin adiponectin ratio did not change in both groups . 25 OH Vit D level significantly increased ( p = 0.022 ) and circulating adiponectin marginally increased ( p = 0.065 ) during 12 month treatment period in active treatment and did not change in placebo group . CONCLUSIONS High doses of  vitamin D supplementation in diabetic patients was associated with significant decrease in AI during one year treatment . This beneficial vascular effect was not associated with improvement in glucose homeostasis parameters Background : Vitamin D deficiency is prevalent in diabetes type 2 and this vitamin may be related to insulin action . This r and omized controlled trial study was done to evaluate the effect of vitamin D supplementation on glucose control and insulin resistance in patients with diabetes type 2 . Methods : Participants of this r and omized clinical trial study consisted of 28 patients with type 2 diabetes who received 100 microgram ( 4000 IU ) vitamin D and 30 diabetic patients who received placebo for 2 months between September 2012 and February 2013 . The effect of vitamin D on glucose control was assessed by measuring HbA1c and insulin resistance as HOMA-IR at the baseline and the end of the intervention . Results : The results showed a significant decrease in HbA1c ( from 7.29 ± 0.22 % to 6.76 ± 0.18 % , P<0.001 ) and insulin concentration ( from 8.24 ± 0.97 μIU/mL to 6.55 ± 0.28 μIU/mL , P=0.048 ) , but a non-significant decrease in HOMA-IR  in vitamin D  group . Also , HDL-C level increased significantly in both of vitamin D ( P=0.046 ) and placebo groups ( P=0.028 ) . Conclusion : It seems that vitamin D supplementation has beneficial effects on glucose homeostasis and can increases insulin sensitivity in diabetic 2 patients To assess the effect of vitamin D supplementation on parameters of insulin sensitivity/resistance ( IS/IR ) and insulin secretion in subjects with polycystic ovarian syndrome ( PCOS ) . A prospect i ve double-blind r and omized control trial was conducted to assess the effect of vitamin D on insulin kinetics in women with PCOS . The trial was conducted in a tertiary care research hospital . A total of 36 subjects with PCOS , aged 18–35 years , were included in this study . Vitamin D3 4000 IU/day versus placebo was given once a month for 6 months and both groups received metformin .  IS ( by whole-body IS index or Matsuda index ) , IR ( by homeostasis model assessment IR ( HOMA-IR ) ) , and insulin secretion ( by insulinogenic index ; II30 ) were the main outcome measures . Secondary outcome included blood pressure ( BP ) , lipid profile , disposition index ( DI ) , and vascular stiffness . Out of 36 subjects who consented , 32 completed the study . Subjects were r and omized into two groups : group A ( n=15 ; metformin and vitamin D 4000 IU/day ) or group B ( n=17 ; metformin and placebo ) . Oral glucose tolerance tests with 75 g glucose were carried out at baseline and 6 months after supplementation . Hypovitaminosis D was observed in 93.8 % of all subjects with mean serum 25 hydroxy vitamin D level of 7.30±4.45 ng/ml . After 6 months of vitamin D supplementation , there was no significant difference in any of the parameters of IS/IR ( area under curve (AUC)–glucose , AUC – insulin , insulin : glucose ratio , HOMA-IR , Matsuda index , insulinogenic index , and DI ) , II30 , and cardiovascular risk factors between the two groups . Supplementation of vitamin D , at a dose of 4000 IU/day for 6 months , did not have any significant effect on parameters of IS/IR and insulin secretion in subjects with PCOS 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 Background : Diabetes mellitus ( DM ) and vitamin D deficiency are major health concerns around the world . Evidence suggests a possible role of vitamin D in improvement of insulin secretion and sensitivity . Objectives : We assessed whether vitamin D supplementation could be used in vitamin D deficient-type II diabetes to improve glucose metabolism , components of metabolic syndrome ( MetS ) and specific inflammatory biomarkers . Patients and Methods : A double blind , r and omized clinical trial was conducted in King Khalid University Hospital , Saudi Arabia to evaluate the effect of cholecalciferol supplementation on glycemic control , MetS components and specific inflammatory biomarkers including tumor necrosis factor-alpha ( TNF-α ) , Interleukin ( IL-6 ) , leptin , adiponectin and vascular cell adhesion molecule-1 ( VCAM-1 ) . Twenty-two patients with type II diabetes with insulin resistance , glycated hemoglobin ( HbA1c ) ≥ 6 ( 42 mmol/mol ) and serum 25(OH)D < 50 nmol/L were r and omized using a computer program to receive either supplementation with cholecalciferol ( 5000 IU/day ) or placebo for 12 weeks . The primary outcome was change in HbA1c levels from baseline . Results : Median [ IQR ] 25(OH)D levels increased significantly in the vitamin D group as 58.1 [ 48 , 67.3 ] nmol/L ( P = 0.002 ) . There was no significant difference in the change of HbA1c between the groups ( P = 0.5 ) with a decrease of -0.1 % [ -1 , 0.5 ] in the vitamin D group and an increase of 0.15 % [ 0.1 , 0.2 ] in the placebo group . A significant improvement was observed in the homeostasis model of assessment of β-cell activity ( HOMA-%B ) ( P = 0.03 ) with vitamin D supplementation compared to baseline . Conclusions : Vitamin D repletion for 12 weeks increased serum vitamin D concentrations and improved β-cell activity in vitamin D-deficient type II diabetes with no significant changes in HbA1c or insulin sensitivity AIM This study was performed to determine the effect of a single , large , intramuscular injection of vitamin D post-partum on glucose tolerance and insulin resistance in women with gestational diabetes . METHODS Forty-five participants in a r and omized controlled trial on gestational diabetes mellitus were divided into an intervention group and a control group . Only subjects in the intervention group received one intramuscular injection of 300,000 IU of vitamin D3 .  HbA(1c ) , serum 25-hydroxyvitamin D3 , fasting insulin and blood glucose , C-peptide , homeostasis model assessment insulin resistance index ( HOMA-IR ) , β-cell function , insulin sensitivity and the Quantitative Insulin Sensitivity Check Index ( QUICKI ) were measured at baseline and after 3 months of intervention . RESULTS Approximately 80 % of the mothers had a degree of vitamin D deficiency . Post-intervention , this was found in 4.2 and 71.4 % in the intervention and control groups , respectively . The medians of HOMA-IR indices before and after intervention were 0.6 and 0.5 ( P = 0.7 ) , respectively , in subjects in the intervention group , and 0.5 and 0.9 ( P = 0.01 ) in subjects in the control group . The mean of the QUICKI fell only in the control group ( P = 0.008 ) . In the control group , β-cell function increased by ~8 % ( P = 0.01 ) and insulin sensitivity decreased after 3 months ( P = 0.002 ) . Post-intervention , the median C-peptide decreased in the intervention group and increased in the control group , but the change was significant only in the control group ( P = 0.03 ) . CONCLUSIONS A single injection of 300,000 IU of vitamin D3 achieves a 3-month serum 25-hydroxyvitamin D range of 50 - 80 nmol/l and is an efficient , effective and safe procedure for improving the vitamin status and indices of insulin resistance in mothers with gestational diabetes after delivery Background Despite the certain role of both vitamin D and adiponectin in the regulation of insulin sensitivity , the interaction between these two agents has remained uncertain . Objective The present study aim ed to determine whether vitamin D is able to change plasma adiponectin and affect glucose homeostasis and insulin sensitivity in first-degree relatives of subjects with type 2 diabetes . Methods This r and omized clinical trial was conducted at Clinic of Shahid Sadoughi Hospital in Yazd , Iran , from January 25 , 2012 to December 25 , 2014 . In this r and omized , double-blinded controlled trial , 64 first-degree relatives of type 2 diabetic patients were assigned r and omly to receive either vitamin D supplement ( 50000 IU vitamin D tablet weekly ) plus lifestyle change as the intervention group ( n = 32 ) or placebo plus lifestyle change as the control group ( n = 32 ) for twelve weeks ( three months ) . Results Fifty-three patients ( 28 in the intervention group and 25 in the control group ) completed the study . Serum levels of vitamin D  increased while insulin level and consequently insulin resistance ( calculated by HOMA formula ) significantly decreased in the case group ( p-value < 0.001 for all variables ) . Although the values of these three biomarkers showed a slight increase in control group , the changes were not statistically significant . The levels of the changes in other markers including adiponectin , Fasting Blood Sugar ( FBS ) , triglyceride , and total cholesterol remained insignificant in both study groups after completing interventions compared with before interventions . Conclusion This study showed that decreased insulin resistance is expected by administrating vitamin D supplement in first-degree relatives of the patients with diabetes mellitus . Trial Registration The trial was registered at the Iranian Registry of Clinical Trials ( http://www.i rct .ir ) with the I RCT ID : 201105176430N1 . Funding The authors received no financial support for the research or publication of this article 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 OBJECTIVES This study intended to assess the effects of the antioxidants ; Alpha Lipoic Acid ( ALA ) , omega 3 fatty acids and vitamin E on the parameters of insulin sensitivity , oxidative stress , lipid metabolism and glycaemic control in patients of type 2 diabetes mellitus . METHODS This was a prospect i ve , r and omized , double blind , placebo controlled , single centred study . One hundred four patients with type 2 diabetes mellitus with insulin resistance were recruited for the study . They were given ALA , omega 3 fatty acids , vitamin E or placebo . Their weight , Body Mass Index ( BMI ) and Waist circumference were measured . The investigations which were fasting glucose and fasting total cholesterol . The insulin resistance was calculated on the basis of the BMI and the waist circumference . RESULTS In the intra group analysis at the baseline ( V1 ) vs at the end of the treatment period ( V5 ) , we observed a significant decrease in the BMI , waist circumference and the total cholesterol in the three treatment groups . In the intergroup analysis at V5 , ALA , omega 3 fatty acids and vitamin E showed a significant improvement in the total cholesterol as compared to the placebo and vitamin E showed the maximum improvement . CONCLUSION ALA , omega 3 fatty acids and vitamin E showed the improvement in insulin sensitivity . Since they differ in improving different parameters all of these three can be used as an add on therapy in patients with type 2 diabetes mellitus to improve their insulin sensitivity and lipid metabolism 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 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 : Background Studies have suggested that vitamin D may be important for both insulin sensitivity and insulin secretion , and that supplementation with vitamin D may subsequently prevent development of type 2 diabetes . Aim of the study The objective of the current study was to test the hypothesis that supplementation with vitamin D would improve glycaemic control in subjects with type 2 diabetes . Methods Thirty-six subjects with type 2 diabetes , treated with metformin and bed-time insulin  , were r and omised to supplementation with cholecalciferol ( 40,000 IU per week ) versus placebo for 6 months . Thirty-two subjects participated throughout the entirety of the study . Fasting blood sample s were drawn before and at the end of the 6 month study without the previous bed-time insulin injection . The insulin and metformin doses were not changed throughout the study . Results After 6 months , the fasting glucose , insulin , C-peptide , fructosamine , and HbA1c levels were not significantly different from baseline values . In addition , changes in these parameters ( values at 6 months minus values at baseline ) did not differ between the vitamin D and the placebo group . Conclusions We were not able to demonstrate that vitamin D supplementation had a significant effect on glucose metabolism in subjects with type 2 diabetes but without vitamin D deficiency . Further studies are needed in larger groups of subjects with type 2 diabetes or impaired glucose tolerance , who also exhibit low serum 25-hydroxyvitamin D levels INTRODUCTION Type 2 diabetes is a major public health problem . Recent epidemiological evidence also points to a potential association of vitamin D insufficiency with adverse metabolic risks , including that for type 2 diabetes . SUBJECTS AND METHOD A double-blind r and omized placebo-controlled trial was carried out . Seventy subjects with type 2 diabetes , age 30 - 75 years old , were r and omly assigned in a double-blind fashion to two groups . One group received two capsules of calcitriol ( 0.25 μg 1,25-dihydroxy cholecalciferol per each capsule ) per day . The second group received placebo tablets . At the beginning , middle and the end of the 12 week supplementation trial , serum glucose , insulin , calcium and phosphorous , HbA1c and 25(OH ) vitamin D were measured . RESULTS There was no significant difference between two groups at baseline . At the end of the study , fasting plasma glucose increased in the control group ( p=0.038 ) , while it remained unchanged in calcitriol group . Level of insulin and HbA1c increased significantly in both groups ( p=0.013 and 0.0004 in treatment and control group ) . Regarding insulin resistance indices , there was a significant change in HOMA-IR and QUICKI in both groups ( p=0.023 and 0.002 in treatment and 0.001 and < 0.001 in control group respectively ) . Insulin secretion as assessed by HOMA-%β , remained relatively unchanged in the control group , while it increased significantly in the treatment group at the end of study ( p=0.009 ) . CONCLUSION Vitamin D supplementation attenuated the increase in glycemia , and increased insulin secretion , but had no effect on insulin resistance OBJECTIVE This study was performed to evaluate the effects of vitamin D and omega-3 fatty acids co-supplementation on glucose metabolism and lipid concentrations in gestational diabetes ( GDM ) patients . METHODS This r and omized double-blind placebo-controlled clinical trial was done among 140 GDM patients . Participants were r and omly divided into 4 groups to receive : ( 1 ) 1000 mg omega-3 fatty acids containing 360 mg eicosapentaenoic acid and 240 mg docosahexaenoic acid ( DHA ) twice a day + vitamin D placebo ( n = 35 ) ; ( 2 ) 50,000 IU vitamin D every 2 weeks + omega-3 fatty acids placebo ( n = 35 ) ; ( 3 ) 50,000 IU vitamin D every 2 weeks + 1000 mg omega-3 fatty acids twice a day ( n = 35 ) , and ( 4 ) vitamin D placebo + omega-3 fatty acids placebo ( n = 35 ) for 6 weeks . RESULTS After 6 weeks of intervention , patients who received combined vitamin D and omega-3 fatty acids supplements compared with vitamin D , omega-3 fatty acids , and placebo had significantly decreased fasting plasma glucose ( -7.3 ± 7.8 , -6.9 ± 6.6 , -4.0 ± 2.5 , and + 1.0 ± 11.4 mg/dL , respectively , P < .001 ) , serum insulin levels ( -1.9 ± 1.9 , -1.3 ± 6.3 , -0.4 ± 6.3 , and + 2.6 ± 6.5 μIU/mL , respectively , P = .005 ) , homeostatic model of assessment for insulin resistance ( -0.7 ± 0.6 , -0.5 ± 1.4 , -0.2 ± 1.5 , and + 0.6 ± 1.5 , respectively , P < .001 ) and increased quantitative insulin sensitivity check index ( + 0.01 ± 0.01 , + 0.008 ± 0.02 , + 0.002 ± 0.02 , and -0.005 ± 0.02 , respectively , P = .001 ) . In addition , changes in serum triglycerides ( -8.2 ± 41.0 , + 7.6 ± 31.5 , + 3.6 ± 29.9 , and + 20.1 ± 29.6 mg/dL , respectively , P = .006 ) and very low-density lipoprotein cholesterol ( -1.6 ± 8.2 , + 1.5 ± 6.3 , + 0.8 ± 6.0 , and + 4.0 ± 5.9 mg/dL , respectively , P = .006 ) in the vitamin D plus omega-3 fatty acids group were significantly different from the changes in these indicators in the vitamin D , omega-3 fatty acids , and placebo groups . CONCLUSION Overall , vitamin D and omega-3 fatty acids co-supplementation for 6 weeks among GDM patients  had beneficial effects on fasting plasma glucose , serum insulin levels , homeostatic model of assessment for insulin resistance , quantitative insulin sensitivity check index , serum triglycerides , and very low-density lipoprotein cholesterol levels
This meta- analysis suggests that vitamin D supplementation improves indices of glycemic control ( FBG , HOMA-IR , and HbA1C ) in patients with diabetes mellitus .
Hence , vitamin D supplements may be of potential therapeutic value in diabetic patients , as an adjuvant therapy along with other treatments
BACKGROUND AND PURPOSE This systematic review and meta- analysis aim ed to assess the effects of vitamin D supplements on indices of glycemic control [ homeostatic model assessment -insulin resistance ( HOMA-IR ) , hemoglobin A1C ( HbA1C ) , fasting blood glucose ( FBG ) , and quantitative insulin-sensitivity check index ( QUICKI ) and lipid profile in diabetic patients .