Potential correlation between plasma total GIP levels and body mass index in Japanese patients with types 1 or 2 diabetes mellitus.

Glucose-dependent insulinotropic polypeptide (GIP) secretion in diabetic Europeans with type 1 (T1DM) and type 2 (T2DM) following test meal (TM) has been shown to be normal. In Japanese patients with T2DM, GIP secretion was also normal. We determined whether GIP secretin is influenced by various factors. Plasma glucose (PG), serum insulin (s-IRI), serum C-peptide (s-CPR), and plasma total GIP (p-total GIP) levels were measured at 0, 30, and 60 minutes after TM (560 kcal) in patients with T1DM (n = 15, group 1) and T2DM (n = 29, group 2) treated with various medications. HbA1c was also measured. At baseline, means of age, BMI, HbA1c, PG, s-CPR, SUIT (secretory unit in transplantation) and p-total GIP were significantly lower in group 1 than in group 2. Each mean of postprandial p-total GIP levels after TM in all patients was more dramatically increased than other factors. The area under the curve (AUC) of p-total GIP levels in early-phase (0 to 30 min) was significantly positively correlated with BMI in group 2 but not in group 1, and not with other factors. These results indicate that the GIP secretion after TM in diabetic Japanese patients was dramatically increased, and the AUC of GIP secretion in early-phase was positively correlated with BMI in non-obese and obese patients with T2DM, but not with T1DM. The increase was not influenced by gender, age, glycemic control, duration of disease, micro- or macro-vascular disturbances, or oral drugs.

Decreased active GLP-1 response following large test meal in patients with type 1 diabetes using bolus insulin analogues.

Postprandial plasma immunoreactive active glucagon-like peptide-1 (p-active GLP-1) levels in type 1 diabetic patients who did not use bolus insulin responded normally following ingestion of test meal, while a small response of p-active GLP-1 levels was seen in type 2 diabetic patients. To determine whether p-active GLP-1 levels are affected by ingestion of test meal in type 1 diabetic Japanese patients who used bolus rapid-acting insulin analogues, plasma glucose (PG), serum immunoreactive insulin (s-IRI), serum immunoreactive C-peptide (s-CPR), and p-active GLP-1 levels were measured 0, 30, and 60 min after ingestion of test meal in Japanese patients without diabetic complications (n=10, group 1) and control subjects with normal glucose tolerance (n=15, group 2). HbA1c levels were also measured in these groups. The patients in group 1 were treated with multiple daily injections or CSII using injections of bolus rapid-acting insulin analogues before ingestion of test meal. There was no significant difference in mean of sex, age, or BMI between groups. Means of HbA1c, basal and postprandial PG, and postprandial s-IRI levels with integrated areas under curves (0-60 min) (AUC) in group 1 were significantly higher than those in group 2. Means of basal and postprandial s-CPR, and postprandial p-active GLP-1 levels with AUCs were significantly lower in group 1 than in group 2. These results indicated that postprandial p-active GLP-1 levels following ingestion of test meal in type 1 diabetic Japanese patients using bolus rapid-acting insulin analogues were decreased relative to those in controls.