The Impact of Chronic Liraglutide Therapy on Glucagon Secretion in Type 2 Diabetes: Insight From the LIBRA Trial.

Abstract

In patients with type 2 diabetes (T2DM), impaired suppression of postprandial glucagonemia is a metabolic defect that contributes to hyperglycemia. Treatment with a glucagon-like peptide-1 agonist can reduce hyperglucagonemia in the acute setting, but little is known about the durability of this effect with long-term treatment. The purpose of this study was to evaluate the impact of chronic liraglutide therapy on glucagon regulation in early T2DM. Design/Setting/Participants/Intervention: In this double-blind, randomized, placebo-controlled trial, 51 patients with T2DM of 2.6 ± 1.9 years' duration were randomized to either daily subcutaneous liraglutide or placebo injection and followed for 48 weeks, with serial assessment of the glucose, insulin, C-peptide, and glucagon responses to a 75-g oral glucose tolerance test every 12 weeks. The glucagon response was assessed with the incremental area under the glucagon curve (iAUCglucagon) from measurements at 0, 30, 60, 90, and 120 minutes on each oral glucose tolerance test. As expected, compared with placebo, liraglutide induced a robust enhancement of the postchallenge insulin and C-peptide response at each of the 12-, 24-, 36-, and 48-week time points, with a concomitant reduction in glycemic excursion. However, liraglutide also induced a paradoxical increase in postchallenge glucagonemia that first emerged at 12 weeks and persisted over the 48-week treatment period. Indeed, baseline-adjusted iAUCglucagon was significantly higher in the liraglutide group compared with placebo at 12 weeks (170.2 ± 34.9 vs 65.4 ± 36.4 pg/mL · 2 hours, P = .04), 36 weeks (162.2 ± 27.9 vs 55.7 ± 30.4 pg/mL · 2 hours, P = .01), and 48 weeks (155.5 ± 26.5 vs 45.7 ± 27.0 pg/mL · 2 hours, P = .006). In contrast to its acute glucagon-lowering effect, chronic treatment with liraglutide is associated with increased postchallenge hyperglucagonemia in patients with early T2DM.