Impaired insulin mediated potassium uptake in adolescents with IDDM

Abstract

Insulin-dependent diabetes mellitus is known to be associated with impaired ability of insulin to enhance tissue glucose uptake. However, no information is available whether or not this insulin resistance extends to insulin-mediated potassium (K+) uptake. Insulin-mediated decrease in serum potassium (K+) and in blood urea nitrogen (BUN) concentration was evaluated in 20 adolescents with IDDM and 10 matched controls during a 3-h hyperinsulinemic (1.7 mU/kg/min)-euglycemic clamp study. Insulin-mediated glucose disposal rate was lower in IDDM compared with controls (37.4 +/- 3.2 vs 63.8 +/- 5.4 mumol/kg/min, P less than 0.001). The decline in serum K+ concentration following hyperinsulinemia was significantly smaller in adolescents with IDDM than controls (0.29 +/- 0.06 vs 0.67 +/- 0.08 meq/liter, P = 0.002). Similarly the decline in BUN concentration was smaller in IDDM compared with control subjects (2.10 +/- 0.40 vs 3.70 +/- 0.56 mg/dl, P = 0.03), suggestive of decreased suppressibility of proteolysis. The changes in serum K+ and BUN concentrations were correlated (r = 0.64, P = 0.02) in controls but not in diabetics. Similarly, the decrement in serum K+ concentration showed a positive correlation with the rate of insulin-mediated glucose disposal (r = 0.68, P = 0.02) in controls but not in diabetics. The correlation of glucose disposal rate with the decline in BUN concentration did not reach a level of significance (r = 0.43, P = 0.1). These results indicate that adolescents with IDDM are resistant to the ability of insulin to stimulate in vivo K+ uptake and to suppress proteolysis.