Changes in Prandial Glucagon Levels After a 2-Year Treatment With Vildagliptin or Glimepiride in Patients With Type 2 Diabetes Inadequately Controlled With Metformin Monotherapy

OBJECTIVE

To determine if the dipeptidyl peptidase-4 inhibitor vildagliptin more effectively inhibits glucagon levels than the sulfonylurea glimepiride during a meal.

RESEARCH DESIGN AND METHODS

Glucagon responses to a standard meal were measured at baseline and study end point (mean 1.8 years) in a trial evaluating add-on therapy to metformin with 50 mg vildagliptin b.i.d. compared with glimepiride up to 6 mg q.d. in type 2 diabetes (baseline A1C 7.3 ± 0.6%).

RESULTS

A1C and prandial glucose area under the curve (AUC)_{0–2 h} were reduced similarly in both groups, whereas prandial insulin AUC_{0–2 h} increased to a greater extent by glimepiride. Prandial glucagon AUC_{0–2 h} (baseline 66.6 ± 2.3 pmol · h⁻¹ · l⁻¹) decreased by 3.4 ± 1.6 pmol · h⁻¹ · l⁻¹ by vildagliptin (n = 137) and increased by 3.8 ± 1.7 pmol · h⁻¹ · l⁻¹ by glimepiride (n = 121). The between-group difference was 7.3 ± 2.1 pmol · h⁻¹ · l⁻¹ (P < 0.001).

CONCLUSIONS

Vildagliptin therapy but not glimepiride improves postprandial α-cell function, which persists for at least 2 years.Glucagon levels are increased in type 2 diabetes because of impaired glucose-mediated suppression of glucagon secretion resulting in increased hepatic glucose output with subsequent hyperglycemia (1). Improved glycemia by the dipeptidyl peptidase-4 inhibitor, vildagliptin (2), is mediated primarily by improved β- and α-cell sensitivity to glucose (3). As an add-on to metformin, vildagliptin displays equal efficacy as glimepiride, with the added benefits of a much lower risk of hypoglycemia and no weight gain (4). Here we report prandial assessments of glucagon levels and insulin secretion rates after up to ∼2 years of therapy with the two drugs.