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- Title
A Reduced-Fat Diet and Aerobic Exercise in Japanese Americans With Impaired Glucose Tolerance Decreases Intra-Abdominal Fat and Improves Insulin Sensitivity but not β-Cell Function.
- Authors
Carr, Darcy B.; Utzschneider, Kristina M.; Boyko, Edward J.; Asberry, Pamela J.; Hull, Rebecca L.; Kodama, Keiichi; Callahan, Holly S.; Matthys, Colleen C.; Leonetti, Donna L.; Schwartz, Robert S.; Kahn, Steven E.; Fujimoto, Wilfred Y.
- Abstract
Lifestyle modification reduces the risk of developing type 2 diabetes and may have its effect through improving insulin sensitivity, β-cell function, or both. To determine whether diet and exercise improve insulin sensitivity and/or β-cell function and to evaluate these effects over time, we quantified insulin sensitivity and the acute insulin response to glucose (AIRg) in 62 Japanese Americans (age 56.5 ± 1.3 years; mean ± SE) with impaired glucose tolerance (IGT) who were randomized to the American Heart Association (AHA) Step 2 diet plus endurance exercise (n = 30) versus the AHA Step I diet plus stretching (n = 32) for 24 months. β-Cell function (disposition index [DI]) was calculated as Si x AIRg, where S[sub i] is the insulin sensitivity index. The incremental area under the curve for glucose (incAUCg) was calculated from a 75-g oral glucose tolerance test. Intra-abdominal fat (IAF) and subcutaneous fat (SCF) areas were measured by computed tomography. At 24 months, the Step 2/endurance group had lower weight (63.1 ± 2.4 vs. 71.3 ± 2.9 kg; P = 0.004) and IAF (75.0 ± 7.9 vs. 112.7 ± 10.4 cm² P = 0.03) and SCF (196.5 ± 18.0 vs. 227.7 ± 19.9 cm² P < 0.001) areas, greater Si (4.7 ± 0.5 vs. 3.3 ± 0.3 x 10-5 min ⋅ pmol[sup -1] ⋅ l[sup -1]; P = 0.01), and a trend toward lower AIRg (294.9 ± 50.0 vs. 305.4 ± 30.0 pmol/l; P = 0.06) and incAUCg (8,217.3 ± 350.7 vs. 8,902.0 ± 367.2 mg ⋅ dl-1 ⋅ 2 h-1]; P = 0.08) compared with the Step 1/stretching group after adjusting for baseline values. There was no difference in the DI (P = 0.7) between the groups. Si was associated with changes in weight (r = -0.426, P = 0.001) and IAF (r = -0.395, P = 0.003) and SCF (r = -0.341, P = 0.01) areas. Thus, the lifestyle modifications decreased weight and central adiposity and improved insulin sensitivity in Japanese Americans with IGT. However, such changes did not improve β-cell function, suggesting that this degree of lifestyle modifications may be limited in preventing type 2 diabetes over the long term. Diabetes 54:340-347, 2005
- Subjects
UNITED States; TYPE 2 diabetes; HYPOGLYCEMIC agents; INSULIN; ENDOCRINE diseases; DIAGNOSIS of diabetes
- Publication
Diabetes, 2005, Vol 54, Issue 2, p340
- ISSN
0012-1797
- Publication type
Article
- DOI
10.2337/diabetes.54.2.340