Effect of dairy consumption and its fat content on glycemic control and cardiovascular disease risk factors in patients with type 2 diabetes: a randomized controlled study

Abstract

Background: Dietary Guidelines for Americans recommend the consumption of 3 servings/d of low-fat/nonfat dairy. The effects of higher dairy consumption and its fat content are unknown in patients with type 2 diabetes.

Objective: Evaluate the impact of higher consumption of high- compared with low-fat dairy on glycated hemoglobin (HbA1c), body weight, and cardiovascular disease risk factors in patients with type 2 diabetes.

Methods: We enrolled 111 subjects with type 2 diabetes (aged 58.5 ± 8.9 y, 47% females, diabetes duration 13.2 ± 8.3 y, HbA1c 8.09 ± 0.96%) who consumed <3 servings of dairy/d. We randomly assigned them into 3 groups: control group maintained baseline dairy intake, low-fat (LF) group incorporated ≥3 servings/d of LF dairy, and the high-fat (HF) group incorporated ≥3 servings/d of HF dairy. We evaluated HbA1c, body weight, BMI, body composition parameters, blood pressure (BP), lipid parameters, homeostatic model assessment of insulin resistance (HOMA-IR), and total energy and macronutrient intake at baseline, and after 12 and 24 wk.

Results: At 24 wk, percent energy from saturated fat increased from baseline in the HF group by 3.6%, (95% CI: 2.2, 5.1) and decreased in the LF group by -1.9% (95% CI: -3.3, -0.4). The LF group increased their percent energy from protein by 4.5% (95% CI: 2.6, 6.4), whereas the HF group decreased their percent energy from carbohydrates by -3.4% (95% CI: -0.2, -6.7). There were no differences in the mean changes in HbA1c, body weight, BMI, body composition or lipid parameters, or BP between the 3 groups at 24 wk.

Conclusion: In patients with type 2 diabetes, increased dairy consumption to ≥3 servings/d compared with <3 servings/d, irrespective of its fat content, while maintaining energy intake has no effect on HbA1c, body weight, body composition, lipid profile, or BP. This trial was registered at clinicaltrials.gov as NCT02895867.

Keywords: HbA1c; body weight; dairy; high-fat; low-fat; type 2 diabetes.

FIGURE 1

Flow of study participants. GAD, glutamic acid decarboxylase; ITT, intent-to-treat; PP, per-protocol.

FIGURE 2

Least-square mean difference ± SEM in HbA1c and body weight during the study by treatment group in the intent-to-treat population (A) and per-protocol population (B). Intent-to-treat population: control group (n = 38); low-fat group (n = 36); high-fat group (n = 37). Per-protocol population: control group (n = 28); low-fat group (n = 22); high-fat group (n = 26). There were no significant differences between the changes in HbA1c and body weight in the 3 groups. Analyses were performed using a linear mixed-effects model (analogous to repeated-measures ANOVA; PROC MIXED) with group, visit, and group-by-visit interaction as fixed effects and subject as a random effect. HbA1c, glycated hemoglobin.