Obesity (a person with a body mass index [BMI] ≥ 30 kg/m2) is a serious health issue in the whole world. It is connected with diabetes mellitus risk (1). Aim: The main aim of our education was to evaluate the efficacy of Laparoscopic Sleeve Gastrectomy (LSG) on the changes in proinsulin and C-peptide levels before and then surgery by 3 months. Methods: Seventy patients were enrolled in our prospective study 20 samples are control group and 50 morbidly obese diabetic patients who have Type 2 Diabetes Mellitus (T2DM) at Department of general surgery. Assessing the effect of Laparoscopic Sleeve Gastrectomy on morbid obese patients with T2DM. All patients were under strict monitoring to record the changes in weight loss and improvement of T2DM markers; Fasting Blood Glucose (FBG), HOMA-IR, HbA1c, C-peptide and Proinsulin/insulin ratio at  follow-up post 3months operative.  Results: There was a greatly notable variance in BMI between baseline and after Surgery. Also levels of C-peptie, Proinsulin and Proinsulin/insulin ratio were all significantly decreased compared to preoperative baseline levels (P<0.001). Conclusion: Laparoscopic Sleeve Gastrectomy is an actual operative procedure to achieve a remarkable weight loss and controller of type 2 diabetes mellitus linked with major decline in leptin, C-peptide heights, Proinsulin and Proinsulin/insulin ratio after Laparoscopic Sleeve Gastrectomy.