Increased hepatic insulin clearance after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) improves glucose tolerance and ameliorates fasting hyperinsulinemia within days after surgery. Improvements in hepatic insulin sensitivity and insulin clearance could contribute importantly to these effects.

The objective of the investigation was to study changes in insulin clearance after RYGB.

This was a prospective study of fasting hepatic insulin clearance and, in a subgroup of patients, postprandial insulin clearance after a meal test before and 1 week, 3 months, and 1 year after RYGB.

The study was conducted at Hvidovre Hospital (Hvidovre, Denmark).

Patients included 2 groups of obese RYGB-patients: 1) type 2 diabetes (T2D) group: 32 patients with T2D (meal test, n = 13), 2) normal glucose tolerance (NGT) group: 32 patients with NGT (meal test, n = 12).

The intervention was RYGB.

Fasting hepatic insulin clearance (fasting C-peptide/fasting insulin). Postprandial insulin clearance (incremental areas under the curve of insulin secretion rates/incremental areas under the curve of insulin).

Fasting hepatic insulin clearance increased after 1 week (P < .01) and further at 3 months (P < .01), remaining elevated 1 year postoperatively (P < .01) with no difference between the T2D and NGT groups. Postprandial insulin clearance changed only in the T2D group with an increase at 1 week (P < .01) that was maintained at 3 months (P = .06) and 1 year (P < .01).

RYGB increases insulin clearance within 1 week after surgery, highlighting the liver as a key organ involved in the early beneficial effect on glucose metabolism. Postprandial insulin secretion may be underestimated postoperatively in patients with type 2 diabetes when evaluated by peripheral insulin concentrations instead of insulin secretion rates or C-peptide.