Vitamin D Levels in Pediatric T1D and T2D

The clinical records of children and adolescents of ages 3–18 years who were treated for T1D and T2D at the Children’s Medical Center of the University of Massachusetts between 2007 and 2013 were reviewed. Subjects were included if they had a diagnosis of diabetes for >12 mo, had HbA1c and 25(OH)D obtained simultaneously, and were on no vitamin D or calcium supplements. Subjects were excluded if they had vitamin D or calcium supplementation at baseline, or the disorders of calcium metabolism, hemoglobinopathies, or malabsorption syndrome such as celiac disease. Eighty-eight subjects with T1D (46 females, 42 males) and 43 subjects with T2D (26 females and 17 males) fulfilled these criteria (Table 1). The diagnosis of T2D was based on fasting blood glucose of ≥7 mmol/L (126 mg/dL), and/or 2-hour postprandial glucose of ≥11.1 mmol/L (200 mg/dL), and/or random blood glucose of ≥11.1 mmol/L (200 mg/dL) with symptoms of polyuria and/or polydipsia. All patients with T2D had negative results for T1D-associated antibodies (insulin, islet cell, glutamic acid decarboxylase, and insulinoma associated-2). Because 25(OH)D level could vary with sunlight exposure, we categorized each subject’s visit according to the seasons as follows: fall (September 22–December 21), winter (December 22–March 21), spring (March 22– June 21), and summer (June 22-September 21) [31] (link). All subjects with T1D received insulin only. Of the 43 patients with T2D, 17 patients received a combination of insulin and metformin, 15 patients received metformin only, while 8 patients received insulin monotherapy.