V itamin D is absorbed into the body through exposure to sunlight, a diet of vitamin-fortified foods, and dietary supplements. The major source of vitamin D absorption is through skin synthesis. Vitamin D receptors have been found in various tissues, including the brain, prostate, breast, colon, pancreas, and immune cells.[1] The estimated worldwide prevalence of vitamin D (25-hydroxyvitamin D [25(OH) D]) deficiency is 30% to 87%.[2] A study in Turkey in 2000 demonstrated that the deficiency prevalence ranged between 44% and 100% in women.[3] Furthermore, studies have revealed a high prevalence of vitamin D deficiency in type 2 diabetes mellitus (T2DM) patients in the Turkish population. [4,5] Recently, vitamin D was found to have various effects on glucose metabolism, obesity, metabolic syndrome, cardiovascular diseases, and cancer, as well as bone metabolism. It has been suggested that vitamin D is involved in insulin sensitivity by controlling calcium flux through the membrane in both beta-cells and peripheral
Objectives:The aim of this study was to further investigate the prevalence of Vitamin D deficiency in diabetes mellitus (DM) patients, as well as the association between hypovitaminosis D and the microvascular complications of type 2 (T2) DM. Methods: This was a cross-sectional, case-control study of 206 T2DM patients and 34 healthy control subjects. Participants were evaluated for the presence of diabetic retinopathy, nephropathy, and neuropathy. Results: The level of serum 25-hydroxyvitamin D (25(OH) D) was significantly lower in the T2DM patients (11.16±3.99 ng/mL vs. 15.58±3.16 ng/mL; p<0.05). Furthermore, 2.7% of the patients were found to have retinopathy (n=53), 3.6% had neuropathy (n=65), and 29.1% of the patients had microalbuminuria (n=60). Although serum 25(OH) D levels were significantly lower in the presence of retinopathy and neuropathy (p<0.05 for both), no significant association between Vitamin D level and microalbuminuria was found. Conclusion: An inverse relationship between the circulating 25(OH) D level and the prevalence of retinopathy and neuropathy in T2DM patients was determined. However, there was no significant association between microalbuminuria and the 25(OH) D level.