Objectives: To evaluate the impact of obesity on fasting and postprandial glucagon-like peptide-1 (GLP-1) levels in type 2 diabetic cases. Background: Obesity is a pathological disease described by the excessive accumulation of fat in the body, which can have detrimental effects on one's health. Methods: This study has been performed on 120 subjects, separated into four groups: Group A: normal subjects (30), Group B: obese persons without diabetes (30), Group C: obese persons with diabetes (30) and Group D: non-obese persons with diabetes (30) at the endocrinology outpatient clinic and inpatient of the Internal Medicine Department of Menoufia University Hospital. Results: There statistically significant variation has been observed among the examined groups according to fasting GLP-1, 1-hour post-prandial GLP1, and 2 hours post-prandial GLP1 (p value less than 0.05). There was a significant negative association among fasting glucagon-like peptide-1 and weight, BMI, HBA1C, & creatinine (r = -0.36, -0.33, -0,23, and -0.23), respectively, with a significant p value <0.05. Also, there was a significant negative association among 1-hour post-prandial glucagon like peptide-1 and weight, BMI, HBA1C, & creatinine (r = -0.58, -0.56, 0,37, and -0.33), correspondingly, with a significant p value less than 0.05. The same results nearly with 2 h post-prandial GLP-1 Conclusion: The study discovered a significant negative association among fasting glucagon-like peptide-1 and weight, BMI, HBA1C, and creatinine, with a negative correlation observed between 1-hour post prandial GLP-1 and weight, BMI, HBA1C, and creatinine.