(30-11-10) A low-glycemic index diet combined with exercise reducesinsulin resistance, postprandial hyperinsulinemia, and

A low-glycemic index diet combined with exercise reduces insulin resistance, postprandial hyperinsulinemia, and glucose-dependent insulinotropic polypeptide responses in obese prediabetic humans.

Solomon TP, Haus JM, Kelly KR, Cook MD, Filion J, Rocco M, Kashyap SR,
Watanabe RM, Barkoukis H, Kirwan JP.

Department of Pathobiology, Lerner Research Institute and Nutrition, Case
Western Reserve University, Cleveland, OH.
Abstract
BACKGROUND: The optimal lifestyle intervention that reverses diabetes risk
factors is not known.

OBJECTIVE: We examined the effect of a low-glycemic index (GI) diet and
exercise intervention on glucose metabolism and insulin secretion in obese,
prediabetic individuals.

DESIGN: Twenty-two participants [mean ?? SEM age: 66 ?? 1 y; body mass index (in
kg/m(2)): 34.4 ?? 0.8] underwent a 12-wk exercise-training intervention (1 h/d
for 5 d/wk at ??85% of maximum heart rate) while randomly assigned to receive
either a low-GI diet (LoGIX; 40 ?? 0.3 units) or a high-GI diet (HiGIX; 80 ?? 0.6
units). Body composition (measured by using dual-energy X-ray absorptiometry
and computed tomography), insulin sensitivity (measured with a hyperinsulinemic
euglycemic clamp with [6,6-(2)H(2)]-glucose), and oral glucose-induced insulin
and incretin hormone secretion were examined. Results: Both groups lost equal
amounts of body weight (-8.8 ?? 0.9%) and adiposity and showed similar
improvements in peripheral tissue (+76.2 ?? 14.9%) and hepatic insulin
sensitivity (+27.1 ?? 7.1%) (all P < 0.05). However, oral glucose-induced
insulin secretion was reduced only in the LoGIX group (6.59 ?? 0.86 nmol in the
prestudy compared with 4.70 ?? 0.67 nmol in the poststudy, P < 0.05), which was
a change related to the suppressed postprandial response of glucose-dependent
insulinotropic polypeptide. When corrected for changes in ?? cell glucose
exposure, changes in insulin secretion were attenuated in the LoGIX group but
became significantly elevated in the HiGIX group.

CONCLUSIONS: Although lifestyle-induced weight loss improves insulin
resistance in prediabetic individuals, postprandial hyperinsulinemia is reduced
only when a low-GI diet is consumed. In contrast, a high-GI diet impairs
pancreatic ?? cell and intestinal K cell function despite significant weight
loss. These findings highlight the important role of the gut in mediating the
effects of a low-GI diet on type 2 diabetes risk reduction.

Source: Am J Clin Nutr. 2010 Oct 27. [Epub ahead of print]

News

---

In evidenza

"L'informazione presente nel sito serve a migliorare, e non a sostituire, il rapporto medico-paziente."

Per coloro che hanno problemi di salute si consiglia di consultare sempre il proprio medico curante.