Endocrine Abstracts

Introduction: Gastric bypass surgery in obese patients results in weight loss, changes in gastrointestinal and pancreatic hormones and improvement of insulin sensitivity.

Methods: GLP-1, insulin and glucose levels were measured after test meal (Fresubin drink a 200 ml; 200 kcal, 15% protein, 30% fat and 55% carbohydrate) before (day 0) and 5, 90 and 180 days after gastric bypass surgery. Glycaemia (mmol/l; glucose oxidase);GLP-1 (Active 7–36) (pM/l; ELISA, ALPCO diagnostics) and insulin (ECLIA, Roche Diagnostics, pmol/l) were determined in 49 obese patients (age: 37.8±1.6; BMI: 43.45±0.77 kg/m²) in 4 separate days in 0, 15, 30, 45, 60, 90 and 120 min.

Results: There were significant difference between area under the glucose curve (X±S.D.): 679.12±31.25 mmol/l × min⁻¹ (day 0) vs 638.77±29.27 (day 5) vs 658.53±38.64 (day 90) and no difference in day 180 (623.37±28.56). There was significant increase in area under the GLP-1 curve in days 5 (980.12±114.09 pmol/l × min^-1), days 90 (682.92±141.39) and days 180 (778.71±210.78) in comparison with day 0 (287.74±118.72) (P<0.05). There was significant difference betwen the area under the insulin curve for days 0 and 5 (33 832.21±3643.67 vs 22 111.59±2399.34) (P=0.002) while there were no differences for day 90 (29 757.06±4135.41) and day 180 (28 378.14±5242.49). There were no significant differences between basal glucose and GLP-1 levels, while there was significant increase in peak GLP-1 levels in day 5 (16.920±2.371), day 90 (14.566±2.914) and day 180 (17.258±3.172) in comparison with day 0 (3.719±1.023) (P<0.05).

Conclusion: GLP-1 response after mixed test meal is significantly increased up to 6 months after gastric bypass surgery. Changes in insulin and glucose levels indicate improvement in insulin sensitivity The improvement in GLP-1 response after test meal after gastric bypass may be responsible for the beneficial metabolic effects of bariatric surgery.