Effects of different protein content and glycemic index of ad libitum diets on diabetes risk factors in overweight adults: the DIOGenes multicentre, randomised, dietary intervention trial.

Abstract

Aims/hypothesis: Diets with different amounts of protein and glycemic index (GI) may be of importance in the control of body weight and metabolic consequences, especially those related to insulin sensitivity. Methods: In DIOGenes, overweight/obese adults in 8 European countries who lost ≥ 8% of initial body-weight (BW) after following a low calorie diet (LCD) were later randomly assigned into five ad libitum interventional groups during 6 months: Low Protein [LP]/Low GI [LGI]; LP/High GI [HGI]; High Protein [HP]/LGI; HP/HGI and a healthy control diet. BW, fasting plasma glucose and insulin as well as an oral glucose tolerance test (OGTT), HOMA-IR, adiponectin and fructosamine levels were determined at the three time points. Results: The LCD period was initiated by 932 adults, 773 were randomised to the 5 diets and 548 completed the intervention. The HP and LGI diets were related to weight-loss management (p<0.05). The LP/HGI diet induced a higher HOMA-IR increase during the 6 months period. The HP and LGI diets were related to decreasing HOMA-IR changes in those patients with the highest weight-loss (≥10% of initial body-weight). The LGI diet also lead to a decrease in fructosamine levels during the intervention (p<0.05). Plasma insulin response was lower in the HP/LGI after 60 and 90min of the beginning of the OGTT at the end of the 6-months intervention (p<0.05). Conclusion/Interpretation: An increase in dietary protein and a reduction in GI content over a 6-month ad libitum dietary intervention are related to a lower drop-out rate and Accepted Article 4 produced favorable effects on glycaemic control and insulin sensitivity in overweight/obese subjects after an initial body-weight loss. The study was registered with ClinicalTrials.gov, number NCT00390637.