The Pattern of Fasting and Post 75 G Glucose Loading of Glucagon-Like Peptide 1 Levels in Obese and Non-Obese Subjects

BACKGROUND: Prevalence of obesity increased sharply recently; it was associated with an increased prevalence of several cardiometabolic diseases. Reduced glucagon-like peptide 1 (GLP-1) secretion is observed among obese subjects in many studies, and it may mediate the failure of insulin secretion response to food intake. AIM: To evaluate the pattern of fasting and post 75 g glucose loading of GLP-1 levels in obese and non-obese subjects. METHODS: An experimental study on the pattern of GLP-1 levels in fasting state and response in post 75 g glucose loading in obese and non-obese subjects, was conducted. Sixteen obese and 16 non-obese subjects were enrolled in the study, with age- and sex-matching in both groups. GLP-1 levels were measured at fasting state (0), 15, 30, 60, and 120 minutes post-glucose loading. RESULTS: The GLP-1 response to glucose loading were similar in obese and non-obese subjects, which increased from fasting state to post glucose loading and reaching the peak levels in 15 minutes, then declined until the end of observation. There was tendency that GLP-1 levels in fasting state and post glucose loading were lower in obese subjects compared to in non-obese subjects (in fasting state, 5.67 vs. 6.16 ng/mL, P = 0.338; in 15 minutes, 6.20 vs. 6.94 ng/mL, P = 0.239; in 30 minutes 6.20 vs. 6.90 ng/mL, P = 0.264; in 60 minutes, 5.77 vs. 6.12 ng/mL, P = 0.242), but the difference were not statistically significant, except in 120 minutes (5.24 vs. 6.67 ng/mL, P = 0.049; in obese and non-obese subjects, respectively). Similar finding was also seen in the pattern of response (delta) of GLP-1 from time-to-time observation among obese and non-obese subjects (0-15 minutes [0.52 vs. 0.8 ng/mL, P = 0.350], 0-30 minutes [0.53 vs. 0.74, P = 0.550], 0-60 minutes [0.11 vs. 0.31 ng/mL, P = 0.546], in 0-120 minute [-0.42 vs. 0.31, P = 0.006]). CONCLUSIONS: The patterns of GLP-1 levels post glucose loading were similar in obese and non-obese subjects which increased from fasting state to post glucose loading, reaching the peak levels in 15 minutes and then declined until the end of observation, except in non-obese subjects where the GLP-1 levels were increased at 120 minutes. There was a tendency of GLP-1 levels in fasting state and post-glucose loading to be lower in obese subjects compared within non-obese subjects.