Postprandial glycemic and insulinemic responses to high-carbohydrate vs high-protein meals in obese normoglycemic subjects with varied insulin sensitivity

The aim of this study was to investigate whether metabolic responses to diet composition differ between obese subjects with varied insulin sensitivity. Fourteen healthy obese normoglycemic male subjects were divided according to their homeostasis model assessment of insulin resistance (HOMA-IR) values: group A, HOMA-IR ≤2.6 (n = 5); group B, 2.6 < HOMA-IR < 5.0 (n = 4); and group C, HOMA-IR ≥5.0 (n = 5) and given, on 2 separate days, either a high-carbohydrate (HC) (58% carbohydrates, 12% protein, and 30% fat) or an equicaloric high-protein meal (52% protein, 18% carbohydrates, and 30% fat). Glucose, insulin, and lactate were determined before and during 4 hours after ingesting the meals. Results showed that within the HC meal, postprandial glucose and insulin responses and the area under the curve for glucose, insulin, and lactate were significantly higher in group C than group A. Comparing meals, the HC meal resulted in significantly higher area under the curve for glucose and insulin in groups A, B, and C and higher lactic acid in B and C than the corresponding values on the high-protein meal. This study illustrates that diet composition should be an important consideration in dietary management of obesity when accompanied by insulin resistance.