T1D glucagon levels disrupted after a meal

Glucagon levels are dysregulated following a meal among patients with type 1 diabetes (T1D), a new study reports. In turn, this may contribute to postprandial hyperglycaemia, independent of residual β-cell effects.

The study included 34 T1D patients who were made to undergo a liquid mixed-meal tolerance test. Concentrations of plasma glucose, C-peptide, and glucagon were measured at baseline, while fasted, and at 30, 60, and 120 minutes after the meal. Twenty-three patients with type 2 diabetes (T2D) were also enrolled as controls.

The T1D participants showed higher levels of glucose and lower levels of C-peptide than their T2D counterparts at all time points during the tolerance test. However, due to the premeal bolus insulin, incremental glucose levels at each measurement were comparable between patient arms.

In both groups, plasma glucagon increased progressively during the tolerance test, peaking at 30 minutes after the ingestion of the mixed meal. Maximum concentrations did not differ between T1D and T2D patients, and neither did any of the change at all time points values relative to baseline.

The glucagon response to the mixed-meal challenge in the T1D group likewise remained comparable across several subgroups. For instance, dividing the patients according to the duration of their diabetes and by their fasting C-peptide levels showed mostly comparable levels of glucagon and change values relative to baseline.

The only exception was at 120 minutes when T1D patients with decreased C-peptide levels showed a significantly greater increase in glucagon as compared to those who had preserved levels of the biomarker.

“The impact of dysregulated glucagon secretion on glucose excursions was observed in the patients irrespective of the residual β-cells. The regulation of postprandial glucagon secretion might be a clue to obtaining further improvements of diurnal glycaemic profiles in patients with T1D,” the researchers said.