Effect of vitamin D₃supplementation on glycated hemoglobin (HbA1c), fructosamine, serum lipids, and body mass index: a randomized, double-blinded, placebo-controlled trial among healthy immigrants living in Norway

Abstract

ObjectiveDespite the suggested role of vitamin D in the prevention of diabetes and cardiovascular disease or its risk factors, the evidence is not consistent and there is a paucity of randomized controlled trials in this field. We aimed to investigate the effect of 16-week daily vitamin D3 supplementation on glycated hemoglobin (HbA1c), fructosamine, body mass index (BMI), and serum lipids.DesignDouble-blind, randomized, placebo-controlled trial.SettingImmigrant community centers in Oslo, Norway.Participants251 healthy adults aged 18–50 years with a non-Western immigrant background. All participants performed the baseline test and 215 (86%) returned to the follow-up test.Intervention16 weeks of daily oral supplementation with either 10 μg vitamin D3, 25 μg vitamin D3, or placebo.Main outcome measuresDifference in absolute change during the 16-week intervention between the intervention groups combined (10 or 25 μg of vitamin D3/day) and placebo, in HbA1c, fructosamine, serum lipids (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides), and BMI.ResultsA total of 215 (86%) participants completed the study. Serum 25-hydroxyvitamin D increased from 29 nmol/L at baseline to 49 nmol/L after intervention, with little change in the placebo group. However, there was no difference in change of HbA1c between those receiving vitamin D3 compared with placebo (mean difference: 0.01% (95% CI −0.04 to 0.06, p=0.7)). Neither did the vitamin D3 supplementation have any effect on the other end points: fructosamine, serum lipids, and BMI.Conclusions16-week vitamin D3 supplementation to healthy immigrants from South Asia, the Middle East, or Africa and now living in Norway with low vitamin D status did not improve HbA1c, fructosamine, lipid profiles, or BMI. An updated meta-analysis of similar published trials showed that our results were generally consistent with those of other studies.Trial registration numberNCT01263288.

Impact of vitamin D therapy on decreasing of proteinuria in type 2 diabetic patients

“…We found no association between using of Vit D and serum Hb A 1c , however different results were reported in other studies, for example, in Madar et al 16-week administration of Vit D 3 to healthy individuals with low Vit D status showed no improvement for HbA 1c (26). Likewise, Ahmadi et al reported no significant difference based on HbA 1C in both case and control groups (21).…”

The Association of Serum 25-Hydroxyvitamin D Concentrations and Elevated Glycated Hemoglobin Values: A Longitudinal Study of Non-Diabetic Participants of a Preventive Health Program

“…Cross-sectional studies overwhelmingly demonstrated the existence of an inverse association of circulating 25-hydroxyvitamin D [25(OH)D], the nutritional biomarker for vitamin D status, with HbA 1c concentration, both in patient groups [ 15 , 16 , 17 , 18 , 19 , 20 , 21 ] and community samples [ 17 , 22 , 23 ], though a few studies failed to confirm this association [ 13 , 24 ]. Randomized controlled trials (RTCs) studying the effect of vitamin D supplementation regimens have been less consistent, with the majority not showing a lowering in HbA 1c values [ 7 , 8 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ] and a minority showing a reduction in HbA 1c concentration [ 33 , 34 , 35 ]. These RCTs typically focused on patient groups with T2D or at risk for T2D.…”

Vitamin D intake and risk of CVD and all-cause mortality: evidence from the Caerphilly Prospective Cohort Study

“…Thus, vitamin D-fortified foods need to be considered as a possible strategy to facilitate population intake of the RNI. Furthermore, a few recent studies have used higher doses of vitamin D in their intervention trials (33)(34)(35) , which also showed no associations of vitamin D intake with CVD risk. The strength of the CAPS is the long (over 20 years) follow-up period.…”