Effetti di diverse tecniche di Chirurgia Bariatrica sull’Omeostasi Metabolica in pazienti Obesi

Bariatric surgery can lead to improvement or even resolution of type 2 diabetes Mellitus (T2DM) with the spectrum of responses depending also on operation procedures. However, many underlying mechanisms of metabolic action of different surgical techniques are still unclear. The aim of this study was evaluate the long-term effects of bariatric surgery on weight loss and T2DM remission and to provide a better understanding of the effects of surgery on β-cell function and incretin secretion. METHODS: The study included 104 obese T2DM patients (66 women and 38 men, ) who were wait-listed for laparoscopic gastric banding (LAGB, 11 subjects, age 47,3±2,9 y, BMI 42,3±2,5 kg/m2), or for laparoscopic Roux-en-Y gastric bypass (RYBP , 77 subjects, age 49,7±0,1 y, BMI 45,7±0,7 kg/m2), or for sleeve gastrectomy (SG, 16 subjects, age 50,9±2,3 y, BMI 50,7±2,2 kg/m2) In 5 patients a mixed meal tolerance test (MMT: 186 Kcal; 53% carbohydrate, 30% fat, 17% protein) was performed before and 1 and 12 months after RYBP to assess hormonal changes. During MMT blood samples were collected for 300 minutes for the measurement of plasma glucose, insulin, C-peptide, lactate and GIP. β-cell function parameters were derived from mathematical modelling of plasma glucose, insulin and C-peptide concentrations. Body composition, fat mass and fat-free mass were evaluated before and 1 and 12 months after RYBP by means of DEXA. RESULTS: The average percentage of weight loss after surgery in the 104 patients was 26,5±1,46% and it was maintained at 24 and 36 months follow-up. Diabetes remission at 3 years follow-up occurred in 56,5% of study participants (in 50,0% of LAGB, 56% of RYBP and 100% of SG). Duration of diabetes was the only significant predictor of diabetes remission at 2 and 3 years. The 5 patients who underwent MMT (according to ClinicalTrials.gov protocol NCT 01767441), showed, 1 month after RYBP, a significant weight loss: ΔBMI=- 4,07±0,26 kg/m2 p<0,001, Δtotal mass= -10,62±0,61 kg, Δtotal-fat= -5,58±0,74 kg p<0,007. HOMA-IR and plasma insulin decreased (HOMA-IR 17,2±4,8 vs 2.7±0.61 p=0,04; plasma insulin 231,36±21,17 vs 64,92±4,41 pmol/L, p=0,02) as well as insulin AUC and lactate AUC (respectively 66,43±10,5 vs 28,67±5,51 nmol/l in 4 hour; p=0,039 and 258,03±34,76 vs 183,77±32,89 mmol/l in 4 hour; p=0,02). Insulin secretion rate significantly improved (p<0,04). CONCLUSIONS Bariatric Surgery appears to be a viable option for the treatment of severe obesity, resulting in long term weight loss and frequent diabetes remission. Our preliminary data suggest that amelioration in glucose homeostasis, evaluated by a physiological stimulus (MMT), could be related to improvement in β-cell function and insulin sensitivity.