Biliopancreatic diversion innonobese patients with type 2 diabetes: impact and mechanisms

Context.Diabetes remission is frequent after biliopancreatic diversion (BPD) in morbidly obese patients with type 2 diabetes (T2D). Data, mechanisms, and clinical indications in nonobese T2D patients are scanty.Objective.To assess remission and investigate insulin sensitivity and ß-cell function after BPD in nonobese patients with long-standing T2D.Design, setting and patients.Clinical research study comparing 15 T2D patients (age 55±1 years, duration 16±2 years, BMI=28.3±0.6 kg/m2, HbA1c=8.6±1.3%) with 15 gender-, age-, and BMI-matched nondiabetic controls. Before surgery, and 2 months and one year later, a 3-hour OGTT, a 5-hour mixed meal test, and a 3-hour euglycemic clamp were performed.Intervention.BPD (distal gastrectomy, proximal ileum anastomosed to remaining stomach, biliopancreatic limb anastomosed to ileum 50 cm from the ileocecal valve).Results.Glycemia improved in all patients, but remission (HbA1c<6.5% and normal OGTT) occurred in 6/15. Insulin resistance (19.8±0.8 μmol.min-1.kgffm-1, p<0.001 vs 40.9±5.3 of controls) resolved already at 2 months (34.2±2.8) and was sustained at one year (34.7±1.6), although insulin-mediated suppression of endogenous glucose production remained impaired. In contrast, ß-cell glucose sensitivity (19[12] pmol.min-1.m-2.mM-1 vs 96[73] of controls, p<0.0001) rose (p=0.02) only to 31[26] at one year, and was lower in non-remitters (16[18]) than remitters (46[33]).Conclusions.In nonobese patients with long-standing T2D, BPD improves metabolic control but induces remission in only ∼40% of patients. Peripheral insulin sensitivity is restored early after surgery, and similarly in remitters and non-remitters, indicating a weight-independent effect of the operation. The initial extent of ß-cell incompetence is the main predictor of the metabolic outcome.