The Difference in Glucagon Response to Breakfast Between Non-Obese Patients With Long-Duration Type 1 and Type 2 Diabetes

Background: A balanced action of insulin and glucagon is essential for treating diabetes. This study aimed to assess the change in blood glucagon levels from fasting to a postprandial state and to compare them between patients with type 1 diabetes (T1DM) and type 2 diabetes (T2DM). Methods: This study enrolled patients with T1DM (n = 13) who had undetectable serum C-peptide levels (< 0.02 ng/mL) and patients with T2DM (n = 13) whose age, gender, and body mass index were matched to cases (1:1) as controls. Plasma glucose, serum C-peptide, and plasma glucagon in fasting and 2 h after consuming a standard breakfast for diabetic patients were measured and compared between groups. Results: There were no significant differences in plasma glucose and hemoglobin A1c levels between patients with T1DM and T2DM. However, fasting plasma glucagon levels were significantly lower in patients with T1DM than those in patients with T2DM (19.2 +/- 13.0 pg/mL vs. 31.6 +/- 18.3 pg/mL, P = 0.029). Furthermore, the glucagon's response to a standardized meal for diabetic patients differed between patients with T1DM and T2DM. Conclusions: The significant difference in glucagon response to the meal may be caused by the abnormal postprandial secretion of glucagon in patients with T1DM. The nutrient ratio of the meal may also influence glucagon secretion.