The Pattern of Response of Plasma Insulin and Glucose to Meals and Fasting During Chlorpropamide Therapy

Abstract

Plasma glucose and immunoreactive insulin levels were determined at frequent intervals in 11 obese diabetics during a control study period of 48 hr consisting of 24 hr of normal dietary intake, followed by 24 hr of fasting. Chlorpropamide in a single daily dose of 500 mg was then instituted after 5 days of treatment, the study was repeated. Four subjects were restudied after 5 weeks of treatment. Before treatment both glucose and insulin rose above and fell fell back to a stable fasting baseline following predetermined meals in a manner similar to that expected in normals. During prolonged fasting, both glucose and insulin tended to fall slightly below baseline levels. Following treatment with chlorpropamide for 5 days, the basic pattern of glucose and insulin levels were unchanged, but the plasma glucose was significantly lower and insulin levels were higher than control values, at all time points after meals and during fasting. The reduction of plasma glucose after 5 days treatment was maintained after 5 weeks of treatment, but insulin levels returned to control levels after this period. Therapeutic doses of chlorpropamide facilitate the normal regulatory stimuli to the pancreatic beta cell rather than imposing independent pharmacologic stimulation.