Beneficial metabolic effects of insulin-like growth factor I in patients with severe insulin-resistant diabetes type A.

Severe insulin resistance type A is due to mutations in the insulin receptor gene and is characterized by glucose intolerance or diabetes mellitus, despite extreme hyperinsulinemia, virilization and acanthosis nigricans. At present, there is no therapy for this condition. Recently, we showed that glucose levels in three such patients are promptly lowered by an i.v. bolus of recombinant human insulin-like growth factor I (rhIGF-I). In the present study, we investigated two of these rare patients again and determined fasting and postprandial glucose, insulin, C-peptide, proinsulin and lipid levels during five control, five treatment and three wash-out days while on a constant diet. Treatment consisted of 2 x 150 micrograms rhIGF-I/kg sc per day, which elevated total IGF-I levels 4.5-fold above the control. Fasting glucose levels (days 1-5) in the two patients were 9.6 +/- 1.3 and 9.2 +/- 1.2 mmol/l, respectively, and fell to 4.4 +/- 0.4 and 5.1 +/- 0.5 mmol/l on treatment days 8-10. Fasting insulin (2950 +/- 450 and 690 +/- 125 pmol/l), C-peptide (2217 +/- 183 and 1317 +/- 235 pmol/l) and proinsulin control levels (125 +/- 35 and 66 +/- 0 pmol/l) also decreased by approximately 65% during rhIGH-I treatment, as did the respective postprandial levels. Lipid levels hardly changed at all. In conclusion, IGF-I appears to correct partially some metabolic sequelae of severe insulin resistance and may, hence, be used as a new therapeutic agent.