Effects of Protein Source and Amount of Saturated Fat on Insulin Sensitivity, Insulin Secretion, and Disposition...

Red and processed meat intake is associated with type 2 diabetes (T2D) incidence, whereas plant-based protein has inverse associations. There is limited knowledge of white meat intake and its effects on T2D risk. Intake of saturated fatty acids (SFAs) may modify these associations.

Our objective was to assess the effects of controlled intake of red meat, white meat, and nonmeat protein sources and concentration of SFAs, keeping weight stable, on glucose homeostasis measures, including disposition index.

Secondary analysis was performed of a subset of participants (n = 46) who underwent frequently sampled oral glucose tolerance testing from a randomized, controlled crossover diet intervention trial (n = 113 in main trial) including adults without cardiovascular disease or diabetes. Diet interventions assessed effect of concentration of SFAs (14% compared with 7%) in 2 arms, and protein source (12% red meat, white meat, and nonmeat) in a crossover design with 4-wk feeding periods and 2-7-wk washout periods. Insulin sensitivity, insulin secretion rate, and disposition index were assessed using linear mixed models.

There were no baseline differences in participant demographic and clinical variables between the 2 SFA arms. We found no significant differences in insulin sensitivity or static and dynamic insulin secretion rate and disposition index by protein source or concentration of SFA (P > 0.05).

In a short-term diet intervention trial in healthy individuals, neither protein source nor concentration of SFAs significantly affects disposition index as a proxy for diabetes risk. This trial was registered at clinicaltrials.gov as NCT01427855.