The association of fasting and postprandial GIP and glucagon levels with glycemic variability evaluated by flash glucose monitoring system in type 1 diabetes

This study is to explore the relationship between serum fasting and postprandial glucose-dependent insulinotropic polypeptide (GIP) and glucagon levels and glycemic variability in type 1 diabetes (T1D).

Twenty patients with T1D and 20 healthy controls were included in the study. Parameters of glycemic variability were obtained from 14-day sensor data provided by a flash glucose monitoring system. A mixed meal at breakfast was provided for the participants and fasting, and postprandial blood samples were collected to evaluate serum GIP and glucagon levels.

There were no significant differences in terms of fasting or postprandial GIP and glucagon levels between the two groups (p > 0.05). However, a negative correlation between duration of diabetes and fasting GIP levels \((r=-0.510,p=0.02)\) $(r=-0.510,p=0.02)$ and a positive correlation between total daily insulin dose and fasting and postprandial GIP levels (r = 0.48, p = 0.03) were found in patients with T1D. Postprandial glucagon correlated positively with time above range (TAR 180) (r = 0.56, p < 0.001) and negatively with the number of hypoglycemic events \((r=-0.46,p=0.03)\) $(r=-0.46,p=0.03)$ .

Our results indicate that serum GIP was associated with the duration of diabetes and daily insulin dose. Moreover, postprandial glucagon is linked to hyperglycemic and hypoglycemic indices in cases of T1D.