Effect of Blueberry Consumption on Cardiometabolic Health Parameters in Men with Type 2 Diabetes: An 8-Week, Double-Blind, Randomized, Placebo-Controlled Trial.

Background: Blueberries are dietary sources of polyphenols, specifically anthocyanins. Anthocyanins have been identified as having a strong association with type 2 diabetes risk reduction; however, to date few human clinical trials have evaluated the potential beneficial health effects of blueberries in populations with type 2 diabetes. Objectives: We investigated the effects of blueberry consumption for 8 wk on cardiometabolic parameters in men with type 2 diabetes. Methods: In a double-blind, parallel-arm, randomized controlled trial, 52 men who are US veterans [mean baseline characteristics: age, 67 y (range: 51-75 y); weight, 102 kg (range: 80-130 kg); BMI (in kg/m(2)), 34 (range: 26-45)] were randomly assigned to 1 of 2 intervention groups. The interventions were either 22 g freeze-dried blueberries or 22 g placebo. The study participants were asked to consume 11 g freeze-dried blueberries or placebo with each of their morning and evening meals along with their typical diet. Results: Mean +/- SE hemoglobin A1c (7.1% +/- 0.1% compared with 7.5% +/- 0.2%; P = 0.03), fructosamine (275.5 +/- 4.1 compared with 292.4 +/- 7.9 micromol/L; P = 0.04), triglycerides (179.6 +/- 10.1 compared with 199.6 +/- 19.9 mg/dL; P = 0.03), aspartate transaminase (23.2 +/- 1.4 compared with 30.5 +/- 2.7 units/L; P = 0.02), and alanine transaminase (35.6 +/- 1.5 compared with 48.3 +/- 2.9 units/L; P = 0.0003) were significantly lower for those consuming blueberries for 8 wk than for those consuming the placebo. Fasting plasma glucose concentrations; serum insulin, total cholesterol, LDL-cholesterol, HDL-cholesterol, and C-reactive protein concentrations; blood pressure; and body weight were not significantly different after 8 wk consumption of blueberries compared with the placebo. Conclusions: Consumption of 22 g freeze-dried blueberries for 8 wk may beneficially affect cardiometabolic health parameters in men with type 2 diabetes.This trial was registered at clinicaltrials.gov as NCT02972996.