The main aim of our education is to assess the effect of sleeve operation for more obese patients (BMI > 35 kg/m²) on C-peptide in serum pre- and post (6 months) laparoscopic sleeve gastrectomysurgery (LSG). Methods: Fifty obese patients (BMI > 35 kg/m²) admitted to Gastrointestinal surgery center at Mansoura university in Egypt and twenty persons (as control group) were enrolled in this prospective study. The patients were submitted to LSG and were monitored for weight loss (BMI change) and improvement; Lipid profile, liver enzymes and C-peptide levels at 6 months follow-up post-operation. Results: There was a highly significant difference between BMI before and after operation. Also, a significant decline in C-peptide levels compared to preoperative levels (P<0.001). Conclusion: LSG is an effective surgical procedure to achieve a significant weight loss and control of C-peptide levels, which reflects a good healthy life for obese patients