ß-cell pancreatic dysfunction plays a role in hyperglycemic peaks observed after gastric bypass surgery of obese patients.

Background: Early and intense hyperglycemic peaks are observed after Roux-en-Y gastric bypass (RYGB).

Objectives: The aim of this observational study was to compare the ß-cell pancreatic function of patients with (PEAK) and without hyperglycemic peaks (NOPEAK).

Setting: Referral bariatric surgery center.

Methods: Insulin secretion rate, clearance, and sensitivity and ß-cell and rate sensitivities were computed after a 75-g oral glucose tolerance test in 42 patients who underwent RYGB.

Results: PEAK patients (n = 18; 30-min glycemia>10.4 mmol/L) did not differ from NOPEAK patients (n = 24) in their presurgery or weight loss characteristics. PEAK patients had significantly higher plasma concentrations of glucose and C-peptide than did NOPEAK patients, whereas insulin and glucagon-like peptide-1 concentrations did not differ. The insulin secretion rate and whole-body insulin clearance (208%) were significantly greater, but insulin sensitivity was significantly less (48%) in PEAK patients. Insulin secretion normalized to plasma glucose was significantly lower in PEAK patients, and the disposition index was reduced (35% to 41% of the values in NOPEAK patients).

Conclusion: We conclude that RYGB reveals a series of dysfunctions leading to hyperglycemia in a subset of patients. In PEAK patients, an insufficient adaptation of ß-cell function to glycemia, an increased insulin clearance, and a decreased insulin sensitivity cumulated to contribute to hyperglycemic peaks.