Effects of Gastric Bypass on Type 2 Diabetes in Patients with BMI 30 to 35

This study aims to investigate if the benefits on glycemic control following Roux-en-Y gastric bypass (RYGB) in morbidly obese type 2 diabetes (T2DM) patients are maintained in the 30–35 kg/m² BMI (body mass index) range, comparing results with those in literature.

The study participants were twenty T2DM patients aging 35–70 years, BMI 30.0–34.9 kg/m², minimum diabetes duration 3 years, glycosylated haemoglobin (HbA1c) ≥7.5 % despite good clinical practice medical therapy, submitted to laparoscopic RYGB, and monitored during 36 months. Twenty-seven matched diabetic patients as controls.

Five females, mean age 57 (42–69) years, weight 96.0 (70–111) kg, BMI 32.9 (30.3–34.9) kg/m², waist circumference 112 (100–128) cm, diabetes duration 14 (3–28) years, HbA1c 9.5 (7.5–14.2) %, and C-peptide 3.2 (1,6–9.1) mcg/l. Ten patients were on insulin. There was no mortality, and there were two major late complications. BMI and waist decreased stabilizing around 25 kg/m² and 92 cm. Fasting serum glucose and HbA1c reached values around 150 mg/dl and 7 %, which subsequently maintained. There was remission in 25 % of cases, control 45 %, and all the others improved. HOMA-IR and insulin sensitivity index normalized at 1 month, then maintained. AIR and insulinogenic index showed no postoperative changes. Diabetes remission correlated negatively with duration (p < 0.05; r ² = 0.61), while control positively with C-peptide (p < 0.05; r ² = 0.19). In the control group, FSG, HbA1c, serum triglyceride, and cholesterol significantly decreased with considerable progressive increase of antidiabetic/antihyperlipemic therapy. All patients had HbA1c >7 % at 2–3 years.

Glycemic control obtained by RYGB in this study was less good than that reported by others, apparently due to different patient selection criteria. Our results do not support RYGB weight loss-independent effect on beta-cell function in the T2DM patients with BMI 30–35 kg/m².