Dietary Protein Intake and Risk of Type 2 Diabetes in US Men and Women

Abstract

Dietary proteins are important modulators of glucose metabolism. However, few longitudinal studies have evaluated the associations between intake of protein and protein type and risk of type 2 diabetes (T2D). We investigated the associations between total, animal, and vegetable protein and incident T2D in 72,992 women from the Nurses' Health Study (1984-2008), 92,088 women from Nurses' Health Study II (1991-2009) and 40,722 men from the Health Professionals Follow-up Study (1986-2008). During 4,146,216 person-years of follow-up, we documented 15,580 cases of T2D. In pooled multivariate models including body mass index, participants in the highest quintiles of percentage of energy derived from total protein and animal protein had 7% (95% confidence interval (CI): 1, 17) and 13% (95% CI: 6, 21) increased risks of T2D compared with those in the lowest quintiles, respectively. Percentage of energy intake from vegetable protein was associated with a moderately decreased risk of T2D (comparing extreme quintiles, hazard ratio =0.91, 95% CI: 0.84, 0.98). Substituting 5% of energy intake from vegetable protein for animal protein was associated with a 23% (95% CI: 16, 30) reduced risk of T2D. In conclusion, higher intake of animal protein was associated with an increased risk of T2D, while higher intake of vegetable protein was associated with a modestly reduced risk.

Keywords: animal protein; diabetes mellitus; dietary protein; nuts; peanuts; type 2 diabetes; vegetable protein; whole grains.

Figure 1.

Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) for type 2 diabetes associated with replacement of 1 serving of individual animal protein foods (dairy foods, poultry, eggs, red meat, and processed meat), refined grains, and potatoes with 1 serving of vegetable protein foods (composite variable comprised of whole grains, legumes, peanuts, peanut butter, and other nuts) in the Nurses’ Health Study (1984–2008), Nurses’ Health Study II (1991–2009), and the Health Professionals Follow-up Study (1986–2008). The models adjusted for age, family history of diabetes, smoking, alcohol intake, physical activity, race/ethnicity, total energy intake, postmenopausal hormone use (Nurses’ Health Study, Nurses’ Health Study II), oral contraceptive use (Nurses’ Health Study II), intakes of sugar-sweetened beverages, fruit, and vegetables, and body mass index. Results were mutually adjusted for other food sources of animal protein, refined grains, and potatoes.