The Role of Vitamin D in Diabetes and Cardiovascular Disease: An Updated Review of the Literature

Table 1

Vitamin D and diabetes.

Study type	Subject division		Population	Vitamin D assessment/supplement	Duration	Conclusion	Citation
Cross-sectional	Non-DM; T2DM patients	100; 698		Vitamin D assessment & main cardiovascular risk factors	—	Prevalence of hypovitaminosis D was higher in diabetic patients with HbA1C, BMI, LDL, and triglycerides than Vitamin D counterparts. 25(OH)D may have an indirect effect mediated by cardiovascular risk factors on CHD	[63]
Cross-sectional	Controls; Case, diabetic retinopathy	110; 94	Chinese	Vitamin D receptor gene polymorphism investigated	—	Diabetes duration, systolic blood pressure, HbA1c, and the rs2228570 T allele were associated with increased risk of diabetic retinopathy	[50]
Prospective case-control	Control; Case (deficient/insufficient serum 25(OH)D3)	30; 31	China	Vitamin D supplement: case, calcitriol 0.25 μg/daily Control, no dose	6 months	No effect on FBG, HbA1c, and AUCC-peptide, but reduced blood pressure, inflammation markers, and proteinuria levels after 6 months from baseline	[43]
Case-cohort	Control (non-GDM); Case (GDM)	517; 135		Vitamin D assessment		Early pregnancy Vitamin D status was found to be inversely associated with GDM	[33]
Prospective cohort	White; Black	8120; 2102	Diverse	Vitamin D assessment	8 years	Risk association in Blacks; No association in Whites	[23]
Case-control	Control; Case, supplemented	68; 69	India	Dose administration: 60,000 IU weekly for 4 weeks and then monthly	1 year	Reduced HbA1c levels, FPG, and 2-h plasma glucose	[28]
Randomized double blind	Control; Subjects (DM patients)	21; 21	Tehran	Dose administration: intramuscular injection 300000 IU of Vitamin D3	3 months	Dose of Vitamin D improved plasma level but had no effect on HbA1c	[27]
Randomized double blind	Placebo; Case, T2DM Vitamin D supplemented	42; 45	UAE	Vitamin D supplementation: phase 1 6000 IU Vitamin D3/day (3 months), phase 2 with 3000 IU Vitamin D3/day, and phase 3 both the arms unblinded and supplemented with 2200 IU Vitamin D3/day for 6 months	1 year	No significant influence on weight, fat mass, or waist circumference. Target levels of S-25(OH)D above 75 nmol/L in this population were not achievable	[25]
Randomized prospective	T1DM male (62%) Female (38%)	25	62% Hispanics	Vitamin D3 (20 000 IU/week) for 6 months, either immediately or after 6 months of observation	1 year	Did not affect glycaemia or markers of inflammation	[21]
Cross-sectional	Female; Male	697; 769	Korean	Vitamin D assessment	—	Significantly decreasing trends for fasting insulin, HOMA-IR, and IFG with increasing 25(OH)D (independent of adiposity)	[18]
Prospective case-control	Control; Case (diagnosed DM)	102; 102	India	Vitamin D assessment	2 years	Controls and cases were deficient in Vitamin D, but it was significantly lower in DM patients. Significant negative correlation between 25(OH)D and HbA1c was observed	[15]