Vitamin D metabolites and minerals involved in bone metabolism were studied in 68 control mothers, 14 gestational diabetics and 68 insulin-dependent diabetics during pregnancy and at delivery. 25(OH)D and 1,25(OH)2D concentrations were significantly (p < 0.001) lower in insulin-dependent diabetics than in the control or gestational diabetic groups. A similar difference was also observed between infants. 24,25(OH)2D, phosphorus and magnesium values were similar in all groups. Corrected calcium values were significantly lower in both mothers (p < 0.001) and infants (p < 0.05) in the insulin-dependent group than in the other two groups. Postpartum, 10% of infants of diabetic mothers received calcium therapy. Our results show alterations in vitamin D and mineral metabolism in pregnant insulin-dependent diabetics and their newborn infants and indicate observation during pregnancy and after delivery.