Calcium regulating hormones in children with insulin dependent diabetes mellitus [IDDM]

ABSTRACT

Recent studies have revealed that altered mineral metabolism is observed in diabetic patients with the complication of osteopenia. In order to elucidate the role of calcium regulating hormones on calcium homeostasis and whether they are linked to glycemic control, we have designed this study. The study included 20 children with insulin dependent diabetes mellitus [IDDM] aged from 5.8 - 13 years and 20 age and sex matched normal children who served as control. Serum level of parathyroid hormone, 1,25 dihydroxy vitamin D, calcitonin, serum total and ionized calcium, phosphorus and magnesium were measured. The study included also measurement of biochemical bone remodeling markers [serum alkaline phophatase and osteocalcin]. Glycemic control was assessed in diabetic children by measurement of fasting blood sugar level and glycosylated hemoglobin. The levels of serum calcium, and magnesium were significantly lower in diabetic patients than control and they were significantly correlated with the fasting blood sugar level. In parallel, significant lower levels of 1,25 dihydroxy vitamin D were observed in diabetic patients than control group and were significantly correlated to glycosylated hemoglobin This may indicate that poor control of diabetes significantly affects the level of this active metabolite of Vitamin D. Serum level of calcitonin was slightly higher in diabetic children than control but this was not statistically significant. The levels of serum osteocalcin were significantly lower in diabetic patients than control and they were significantly correlated with the level of glycosylated hemoglobin This may indicate that the degree of metabolic control and duration of disease affected it. It was concluded that, in IDDM, an osteoblastic deficit appears to exist with decreased bone turnover and increased bone resorption. This deficit is aggravated by lower level of 1,25 dihydroxy vitamin D, increased levels of calcitonin and failure of activation of parathyroid hormone. Glucosuric induced osmotic diuresis may also be responsible for the negative calcium balance observed in these patients