Adults with obesity and prediabetes assigned to a high-protein, hypocaloric diet reverted to normal glucose tolerance at 6 months, according to results from a randomized feeding study.
“Protein intake by itself induces insulin release; however, it is a much less potent secretagogue for insulin than is glucose in normal individuals,” Frankie B. Stentz, PhD, of the department of medicine at the University of Tennessee Health Science Center, and colleagues wrote. “This suggests that [high-protein] diets may help preserve the beta cells by increasing sensitivity and decreasing insulin load per meal.”
In a prospective, randomized trial, Stentz and colleagues analyzed data from 24 men and women with prediabetes (HbA1c, 5.7%-6.4%) and BMI between 30 kg/m² and 55 kg/m². Researchers randomly assigned 12 participants to a high-protein diet (30% kcal from protein; 40% kcal from carbohydrates; 30% kcal from fat) and 12 participants to a high-carbohydrate diet (15% kcal from protein; 55% kcal from carbohydrates; 30% kcal from fat). Participants underwent a mixed-meal tolerance and oral glucose tolerance testing at baseline and 6 months, as well as a DXA scan to assess body composition and indirect calorimetry to determine resting metabolic rate. Researchers established caloric needs for participants; 500 kcal were subtracted from the determined caloric needs to promote weight loss between 1 lb and 2 lb weekly. Participants came in weekly to pick up all food and daily food records; compliance and diet adherence was checked at pickup.
At 6 months, all participants assigned to the high-protein diet experienced remission to normal glucose tolerance; 33% of participants in the high-carbohydrate group experienced remission. Both groups experienced weight loss at 6 months from baseline with no significant between-group differences. Both groups also experienced improvements in HbA1c and insulin sensitivity; however, improvements in the high-protein diet group were greater (6-month HbA1c, 5.46% vs. 5.73%; P < .0001; 6-month homeostasis model of assessment for insulin resistance [HOMA-IR], 1.56 vs. 3.34; P < .0001). The high-protein group also saw greater improvements in triglycerides, LDL cholesterol, oxidative stress, tumor necrosis factor-alpha and interleukin-6, suggesting a better anti-inflammatory effect vs. the high-carbohydrate plan.
“To the best of our knowledge, this is the first lifestyle intervention study where 100% remission of prediabetes was obtained,” the researchers wrote. “Our results show that high efficacy can be achieved with dietary modification if parameters are rigorously controlled and monitored.” – by Regina Schaffer
Disclosure: The American Diabetes Association and the AD Baskin Research Fund funded this study. The researchers report no relevant financial disclosures.