Impact of a High Intake of Dairy Product on Insulin Sensitivity in Hyperinsulinemic Adults: A Crossover Randomized Controlled Trial

BACKGROUND: Dairy product intake has been associated with decreased risk of type 2 diabetes (T2D) in cohort studies. However, results from clinical trials on T2D-related risk factors remain inconclusive. OBJECTIVE: The aim of this clinical trial was to evaluate the impact of high dairy product intake (HD) (≥4 servings/d) for 6 wk, compared with an adequate dairy product intake (AD) (≤2 servings/d), on glycemic and insulinemic parameters, insulin sensitivity, insulin secretion, and β-cell function in hyperinsulinemic adults. METHODS: In this crossover clinical trial, hyperinsulinemic adults were randomly assigned to HD or AD for 6 wk, then crossed over after a 6-wk washout period. Serum glucose, insulin, C-peptide, HOMA-IR, Matsuda index, insulinogenic index, and disposition index were measured and analyzed using a repeated-measures mixed model adjusted for age, sex, and BMI. Anthropometric measures were collected and food intake was evaluated using a validated FFQ. RESULTS: Nineteen men and 8 women completed the study (mean ± SD age: 55 ± 14 y; BMI: 31.3 ± 3.3 kg/m(2). Dairy product intake was 5.8 servings/d in the HD condition and 2.3 servings/d in the AD condition after 6 wk. No difference was observed between HD and AD after 6 wk for all outcomes. CONCLUSIONS: HD does not affect glycemic and insulinemic parameters, insulin sensitivity, insulin secretion, and β-cell function over AD in hyperinsulinemic adults. Additional larger and longer studies assessing T2D-related risk factors are required. This trial was registered at clinicaltrials.gov as NCT02961179.