Prevalence of vitamin D deficiency in urban south Indians with different grades of glucose tolerance

The present study assessed the prevalence of vitamin D deficiency in an urban south Indian population in individuals with different grades of glucose tolerance. A total of 1500 individuals (900 normal glucose tolerance (NGT), 300 prediabetes and 300 with type 2 diabetes mellitus (T2DM)) who were not on vitamin D supplementation were randomly selected from the Chennai Urban Rural Epidemiological Study follow-up study. Anthropometric, clinical examination and biochemical investigations (25-hydroxyvitamin D (25(OH)D), insulin, glycated Hb (HbA1c) and serum lipids) were measured. Vitamin D deficiency was defined as serum 25(OH)D < 20 center dot 0 ng/ml, insufficiency as 20-29 center dot 9 ng/ml and sufficiency as >= 30 ng/ml. Of the 1500 individuals studied, 45 % were males and the mean age was 46 (sd12) years. Vitamin D levels lowered with increasing degrees of glucose tolerance (NGT: 21 (sd11); prediabetes: 19 (sd10); T2DM: 18 (sd11) ng/ml,P< 0 center dot 001). The overall prevalence of vitamin D deficiency was 55 % and was significantly higher among individuals with T2DM (63 %) followed by prediabetes (58 %) and NGT (51 %) (P-for trend< 0 center dot 001). Women had 1 center dot 6 times the risk of vitamin D deficiency compared with men (unadjusted OR 1 center dot 6 (95 % CI 1 center dot 3, 2 center dot 0) and adjusted OR 1 center dot 6 (95 % CI 1 center dot 2, 1 center dot 9)). However, there was no increasing trend observed with increasing age. The prevalence of abdominal obesity (66v. 49 %), generalised obesity (80v. 64 %), the metabolic syndrome (45v. 37 %) and insulin resistance (38v. 27 %) was significantly higher in those with vitamin D deficiency compared with those without. This study shows that vitamin D deficiency is highly prevalent in this urban south Indian population and was higher among individuals with T2DM and prediabetes compared with those with NGT.