Effect of prolonged oral terbutaline therapy on glucose tolerance in pregnancy

Abstract

Our objective was to elucidate the pathophysiologic effects and potential reversibility of terbutaline-induced changes in carbohydrate metabolism. We prospectively evaluated serum glucose, insulin, glucagon, C-peptide, and pancreatic polypeptide levels in response to a 100 gm glucose challenge (oral 3-hour glucose tolerance test) in 17 obstetric patients without complications who were given terbutaline (5 mg orally every 4 hours) for 5 consecutive days between 24 and 32 weeks' gestation. Each patient served as her own control, with day 1 representing pretreatment, day 7 the treatment phase, and day 14 the posttreatment evaluation. Body mass index and posttreatment serum terbutaline levels were also measured. A significant initial treatment effect (day 1 versus 7) was observed for glucose (elevated), insulin (elevated), insulin/glucose ratio (elevated), and pancreatic polypeptide (elevated). A significant delayed treatment effect (day 1 versus 14) was also observed for insulin (elevated), insulin/glucose ratio (elevated), and pancreatic polypeptide (elevated). Body mass index directly correlated with postchallenge measures of insulin, insulin/glucose ratio, pancreatic polypeptide, and C-peptide. Posttreatment serum terbutaline levels directly correlated with pancreatic polypeptide, but not with other parameters. Our data support a dose-independent, terbutaline-induced glucose intolerance mediated by glucagon and caused by diminished insulin sensitivity.