Vitamin D Levels in Subjects With and Without Type 1 Diabetes Residing in a Solar Rich Environment

Abstract

OBJECTIVE Previous studies, largely in northern Europe, have suggested an association between type 1 diabetes and reduced serum 25-hydroxy(OH) vitamin D levels, a concept we tested in individuals residing in a solar-rich region (Florida). RESEARCH DESIGN AND METHODS Serum samples from 415 individuals residing in Florida were cross-sectionally analyzed: 153 control subjects, 46 new-onset type 1 diabetic patients, 110 established type 1 diabetic patients (samples ≥5 months from diagnosis), and 106 first-degree relatives of the diabetic patients. RESULTS In this study, 25-OH vitamin D levels (median, range, interquartile range [IQR]) were similar among control subjects (20.1, below detection [bd]–163.5, 13.0–37.4 ng/ml), new-onset type 1 diabetic patients (21.2, bd–48.6, 12.2–30.2 ng/ml), established type 1 diabetic patients (23.2, bd–263.8, 13.8–33.9 ng/ml), and first-degree relatives (22.2, bd–59.9, 12.7–33.1 ng/ml) (P = 0.87). Mean 25-OH vitamin D levels were less than the optimal World Health Organization level of 30 ng/ml in all study groups. CONCLUSIONS Reduced serum 25-OH vitamin D levels were not specifically associated with type 1 diabetes. The uniform suboptimal 225-OH vitamin D levels, despite residence in a zone with abundant sunshine, support additional dietary vitamin D fortification practices.