Normalization of the Growth Hormone and Catecholamine Response to Exercise in Juvenile-Onset Diabetic Subjects Treated with a Portable Insulin Infusion Pump

Abstract

The plasma growth hormone, epinephrine, and norephinephrine responses to cycle ergometer exercise (15 min at 1 W/kg) were examined in 10 juvenile-onset, insulin-dependent diabetics (ages 10–32 yr) during conventional insulin treatment and after 7 and 14 days of treatment with a portable subcutaneous insulin infusion system that normalizes plasma glucose. During conventional insulin treatment (mean plasma glucose, 205 ± 22 mg/dl), the growth hormone response to exercise was sevenfold greater than in normal controls (P < 0.01). After 1 wk of insulin pump treatment (mean plasma glucose, 89 ± 3), the growth hormone response fell 62% (P < 0.001); by 2 wk the growth hormone response had fallen 83% (P < 0.001) to values comparable to those of controls. Exercise resulted in a two- to threefold rise in plasma epinephrine in diabetics (P < 0.001) during conventional treatment but failed to elicit a consistent increment in epinephrine in normal control subjects or in the diabetic patients after 14 days of pump treatment. The rise in plasma norepiriephrine after exercise in conventionally treated diabetic patients was 12-fold greater than in healthy control subjects (P < 0.025) but fell 82% (P < 0.001) after 7 days and 88% (P < 0.001) after 14 days of pump treatment to values similar to those of controls. These data indicate that treatment of insulin-dependent diabetics with a subcutaneous portable insulin infusion system that normalizes plasma glucose results in normalization of the growth hormone and catecholamine response to exercise within 7 to 14 days of institution of treatment.