Changes in dietary protein intake differentially affect glucose tolerance and lipid profile in adults with impaired versus normal glucose tolerance

Abstract

The effects of changes in total protein intake (PRO) on oral glucose tolerance (GT) and lipid‐lipoprotein profile (LLP) were studied in 136 overweight/obese 35–65y, free feeding adults who consumed supplements with 400 kcal/d and 0, 20, 40 or 60 g/d whey protein and exercised 3d/week for 9 months. Retrospectively, subjects were divided into impaired GT (baseline 2‐h glucose > 140 mg/dL) and normal GT groups. Insulin sensitivity was assessed by the Homeostatic Model Assessment (HOMA: 405/(glucosef (mg/dL) • insulinf (U/L)). A multiple regression model assessed the moderating effects of impaired GT on the impact of change in PRO on the GT, HOMA and LLP parameters (adjusted for weight change and gender). A change in PRO was positively associated with changes in HOMA, fasting triacylglycerol (p<0.05) and fasting insulin (p=0.060) in the GT impaired group only (group by PRO, p < 0.05, < 0.05 and 0.061). Change in PRO was not associated with changes in glucose and insulin responses to a 75‐g oral glucose tolerance challenge, or changes in total cholesterol and HDL. In summary, while most research has focused on the effects of total protein intake on health‐related outcomes, these results indicate that the change in protein intake is also important to consider when helping overweight/obese adults with impaired glucose tolerance improve their health.Support: US Whey Protein Res Consort; NIH T32AG025671 and UL1 RR025761