Erythromycin improves glycaemic control in patients with Type II diabetes mellitus

Erythromycin mimics the effect of the gastrointestinal hormone motilin by binding to its receptor and acting as a motilin agonist. We recently found that motilin stimulates insulin secretion at lower doses than doses required to stimulate gastric contractile activity. We studied the effects of erythromycin on insulin secretion and glycaemic control in patients with diabetes mellitus.

Inpatients (n = 34) with Type II (non-insulin-dependent) diabetes mellitus were randomly assigned to receive either erythromycin (400 mg orally three times a day, n = 19) or a placebo (n = 15) for 1 week (first study). Another 34 outpatients with Type II diabetes were also treated with erythromycin (200 mg orally three times a day, n = 17) or a placebo (n = 17) for 4 weeks (second study). Finally, nine inpatients with Type II diabetes and eight normal control subjects received intravenous erythromycin (10 mg x kg(-1) x h(-1)) or saline infusion and insulin secretion was examined (third study).

Erythromycin lowered fasting blood glucose and fructosamine concentrations (p < 0.01) and increased basal as well as glucose-stimulated insulin secretion (p <0.05-0.01) (first study). Low doses of erythromycin treatment for 4 weeks also significantly improved glycaemic control in Type II diabetic patients (second study). Erythromycin infusion significantly increased plasma insulin and decreased glucose concentrations in Type II diabetic and control subjects and greatly potentiated glucose-induced insulin secretion in the latter (third study).

These results indicate that erythromycin given orally has an antidiabetogenic effect and therefore erythromycin derivatives that lack the antibacterial activity could have a therapeutic value in Type II diabetic patients.