Recombinant IGF-I therapy in insulin-dependent diabetes mellitus

Recombinant insulin-like growth factor-I (IGF) has both anabolic and insulin-like effects. In adolescent insulin-dependent diabetes mellitus (IDDM), the GH/IGF-I axis is abnormal, with elevation of growth hormone (GH) secretion and subnormal IGF-I levels. The elevated GH levels contribute to pubertal insulin resistance, making glycaemic control difficult to achieve. Theoretically, rhIGF-I could replace IGF-1 and lower GH by negative feedback effects, hence improving glycaemic control. Two preliminary studies are described in this paper. In the first study, rhIGF-I 40 micrograms/kg s.c. was given as an adjunct to insulin at 1800 h. RhIGF-I induced a significant fall in mean overnight GH secretion and in the insulin infusion rate required to maintain euglycaemia. In the second study, rhIGF-I was given in a dose of 40 micrograms/kg s.c. for 1 month. The dose of isophane insulin fell during puberty, as did HbA1c. These preliminary studies suggest that rhIGF-I given in conjunction with regular insulin therapy may reverse abnormalities in the GH/IGF-I axis and therefore contribute to improvement of glycaemic control in adolescents with IDDM.