Incretin secretion is not restored by short-term strict glycaemic control in Korean hyperglycaemic patients with type 2 diabetes

Aims: To determine whether short-term strict glycaemic control could restore incretin secretion in type 2 diabetic patients. The factors associated with incretin levels were also investigated. Methods: A meal tolerance test (MTT) was performed in eighteen poorly controlled (pDM) and fifteen well controlled (wDM) diabetic patients. Fourteen patients in the pDM group underwent follow-up MTT after strict glycaemic control. The secretions of intact glucagon-like peptide-1 (iGLP-1) and total glucose-dependent insulinotropic polypeptide (tGIP) during MTT were calculated by total and incremental area under the curve (TAUC and IAUC) values. Results: Posttreatment HbA1c level was significantly improved in the pDM group (11.2 ± 0.9 to 7.9 ± 0.9%). However, the secretion of incretin hormones was not increased in the posttreatment pDM group (TAUCiGLP-1, 3612 ± 587 to 2916 ± 405. pmol/L. min; TAUCtGIP, 9417 ± 1099 to 8338 ± 903. pmol/L. min). IAUCiGLP-1 was negatively correlated (r = -0.446, P = 0.011) and independently associated (β = -137.2, P = 0.027) with insulin resistance assessed by homeostasis model assessment. Conclusions: Incretin secretion is not restored by short-term strict glycaemic control. Decreased incretin secretion seems to develop early in the course of type 2 diabetes with increasing insulin resistance, but not to be influenced by glycaemic status.