Weight loss reduces abdominal fat and improves insulin action in middle-aged and older men with impaired glucose tolerance

• Published in: Metabolism, clinical and experimental clinical and experimental, 1995-11, Vol.44 (11), p.1502-1508
• Main Authors: Colman, Eric, Katzel, Leslie I., Rogus, Ellen, Coon, Patricia, Muller, Denis, Goldberg, Andrew P.
• Format: Article
• Language: English
• Subjects: Abdomen; ABDOMINAL FAT; Adipose Tissue - metabolism; Aged; AGING; Aging - metabolism; Aging - physiology; AZUCAR EN SANGRE; Biological and medical sciences; Blood Glucose - analysis; BLOOD SUGAR; Body Composition - physiology; Body Constitution; Diabetes Mellitus, Type 2 - metabolism; Diabetes Mellitus, Type 2 - physiopathology; Diabetes. Impaired glucose tolerance; DISTRIBUCION; DISTRIBUTION; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; ENVEJECIMIENTO; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Glucose - metabolism; Glucose - pharmacology; Glucose Clamp Technique; Glucose Tolerance Test; GRAISSE ABDOMINALE; GRASA ABDOMINAL; HOMBRES; HOMME; Humans; INSULIN; Insulin - blood; Insulin - pharmacology; INSULIN RESISTANCE; Insulin Resistance - physiology; INSULINA; INSULINE; Male; Medical sciences; MEN; Middle Aged; Prospective Studies; REDUCCION DEL PESO; REGIME POUR REDUCTION DE POIDS; SUCRE DU SANG; VIEILLISSEMENT; Weight Loss - physiology; WEIGHT REDUCTION
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1016/0026-0495(95)90153-1

Aging is associated with an increased accumulation of abdominal fat, glucose intolerance, and insulin resistance. We tested the hypothesis that diet-induced weight loss would reduce the abdominal distribution of fat and improve glucose tolerance and insulin action in a group of obese middle-aged and older men with normal or impaired glucose tolerance (IGT). Oral glucose tolerance tests (OGTTs) were performed at baseline and after 9 months of diet-induced weight loss in 35 men (mean age, 60 ± 8 years). Fifteen men of comparable age and degree of obesity who did not participate in the weight loss intervention served as controls. Subjects lost 9.0 ± 2.0 kg (mean ± SD) body weight ( P < .001), resulting in a 19% reduction in percent body fat (30.0 ± 4.0% to 24.0% ± 4.0%, P < .001), an 8% reduction in waist circumference (104.0 ± 7.0 to 96.0 ± 7.0 cm, P < .001), and a 2% reduction in waist to hip ratio [WHR] (0.97 ± 0.06 to 0.95 ± 0.06, P < .01). Weight loss improved glucose tolerance: nine men with IGT at baseline reverted to normal glucose tolerance following the intervention. Glucose area during the OGTT was significantly reduced after weight loss (−22.0%, P < .001), while it increased in control subjects (+32%, P < .004). In multiple regression analysis, the improvement in glucose area following weight loss in these 35 men was attributed to the reduction in waist circumference ( P < .01) and baseline glucose area ( P < .05). Insulin response to glucose and tissue sensitivity to endogenous insulin were measured in a subset of eight men using the hyperglycemic clamp technique. Weight loss resulted in significant reductions in acute ( P < .05) and second-phase ( P < .01) insulin responses and a significant increase in the rate of glucose utilization ([M] P < .05), indicative of increased tissue sensitivity to insulin. Our results support the hypothesis that weight loss significantly improves glucose tolerance and insulin action in obese middle-aged and older men with normal glucose tolerance or IGT, in part by reducing the distribution of fat in upper-body sites.