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Non-diabetic patients

Rapid improvement in insulin sensitivity post-surgery

RYGB improved Adipo-IS and M/I, but there was no change in ISR or DI in either surgical group

Non-diabetic obese patients who have bariatric surgery reported an improvement in  insulin sensitivity (IS), with more pronounced improvements for roux-en-y gastric bypass (RYGB) than for laparoscopic adjustable gastric banding (LAGB), according to a study published in Diabetes Care.

Although bariatric surgery has been shown to have important long-term metabolic effects resulting in enhanced insulin sensitivity and improved glucose tolerance in patients with type 2 diabetes, the contribution of reduced caloric intake to these beneficial effects of surgery remains unclear.

In the study, ‘Short-Term Effects of Laparoscopic Adjustable Gastric Banding Versus Roux-en-Y Gastric Bypass’, Dr Amalia Gastaldelli from the CNR Institute of Clinical Physiology in Pisa, Italy, and colleagues compared the short-term effects (one week) of bariatric surgical procedures with a very low caloric intake (VLCI) on insulin sensitivity (IS) and insulin secretion (ISR) in non-diabetic obese subjects.

Twenty obese patients without diabetes (BMI 44.2±0.7) were admitted to the clinic for one week. At baseline and one week after VLCI (600 kcal/day), subjects received a hyperinsulinemic-euglycaemic clamp with tracer infusion to quantify endogenous glucose production (EGP), lipolysis (rate of appearance of glycerol [RaGlycerol]), peripheral insulin sensitivity (insulin-stimulated glucose disposal [M value] divided by the steady-state plasma insulin concentration [M/I]), hepatic insulin sensitivity (Hep-IS [= 1/(EGP × insulin)]), and adipose insulin sensitivity (Adipo-IS [= 1/(RaGlycerol × insulin)]). An intravenous glucose bolus was administered at the end of the insulin clamp to measure ISR and β-cell function (disposition index [DI]).

Some three months later, patients were admitted for LAGB (n=10) or RYGB (n=10), and were re-studied one week after surgery under the same caloric regimen (600kcal/day).

The researchers found that patients lost 2.1kg after one week of VLCI, with no significant changes in hepatic insulin sensitivity (Hep-IS), adipose insulin sensitivity (Adipo-IS), peripheral insulin sensitivity (M/I), or disposition index (DI). Greater weight loss was seen with RYGB (5.5kg) and LAGB (5.2kg), which also correlated with significant improvement in Hep-IS, endogenous glucose production, and lipolysis. RYGB improved Adipo-IS and M/I. There was no change in ISR or DI in either surgical group.

"Bariatric surgery improves IS within one week," the authors write. "These metabolic effects were independent of caloric intake and more pronounced after RYGB compared with LAGB."

The study was funded by F Hoffmann-La Roche.

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