Diminished Glucose Tolerance and Immunoreactive Insulin Response in Patients with Nonischemic Cardiac Disease

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Abstract
Intravenous infusion of glucose in patients with compensated nonischemic cardiovascular disease has demonstrated that the glucose disappearance slope, G K , is significantly lower than in normal subjects. Immunoassay of plasma insulin in 13 of these cardiac patients showed a reduced insulin response to hyperglycemia in the majority. All had a delayed decline of plasma insulin values. Plasma free fatty acids (FFA) were significantly elevated in the fasting state but were not significantly correlated with the reduced G K . During the acute hyperglycemia, plasma free fatty acid, potassium, and inorganic phosphate concentrations declined as in the normal subjects. Although cardiac index was reduced in most patients, a linear correlation with G K was not obtained. To examine the possible role of enhanced sympathetic stimulation seen in cardiac patients, norepinephrine was infused into normal subjects during a glucose-tolerance test (GTT). A decline in glucose tolerance and plasma insulin was observed to levels approximating those seen in the cardiac patients, suggesting a neurohumoral mechanism for the glucose intolerance in cardiac patients. It would therefore appear that the glucose intolerance in compensated cardiac subjects with a reduced cardiac output is frequently an acquired rather than a genetically determined metabolic disorder.