Increased Maternal Bone Formation in Type I Diabetic Pregnancies

Abstract.

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 A₁ 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 μg/liter, control 115 μg/liter, P= 0.0014), but there was no significant difference in the circulating levels of ICTP between the two groups (median IDDM 4.6 μg/liter, control 4.6 μg/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.