Increased maternal bone formation in type I diabetic pregnancies.

There is evidence that infants of insulin-dependent diabetics have increased intrauterine bone resorption and reduced bone mineral content at birth. The aim of this study was to determine if type I diabetes is associated with abnormal maternal bone metabolism. We measured the circulating levels of carboxyterminal propeptide of type I procollagen (PICP) and cross-linked carboxyterminal telopeptide of type I collagen (ICTP) in the third trimester of pregnancy in samples obtained from 19 pregnant women with type I diabetes and 19 pregnant controls, to monitor the rate of bone formation and degradation, respectively. Diabetic control was considered to be good as the mean hemoglobin A(1) level was less than 8.5%. The circulating levels of PICP were significantly higher in pregnant women with insulin-dependent diabetes than in controls with uncomplicated pregnancy (median IDDM 147 microgram/liter, control 115 microgram/liter, P = 0.0014), but there was no significant difference in the circulating levels of ICTP between the two groups (median IDDM 4.6 microgram/liter, control 4.6 microgram/liter, P = 0.907). Therefore, our findings suggest that there is an increase in bone formation in pregnant women with type I diabetes which may be related to the increased amount of insulin administered and the improvement in diabetic control associated with pregnancy.