Longitudinal associations of serum fatty acids derived from dairy consumption with early prediabetes phenotypes: The PROspective Metabolism and ISlet cell Evaluation (PROMISE) cohort.

BACKGROUND

Dairy derived saturated and trans fatty acids may contribute to inverse associations of dairy intake with type 2 diabetes mellitus (T2DM) risk. Longitudinal studies examining this association are limited. This study investigated longitudinal associations of 15:0, trans-16:1n9, trans-18:1n11, and c9, trans-11 conjugated linoleic acid (CLA) in four serum fractions with insulin sensitivity, beta cell function and glucose concentrations.

METHODS

Data were obtained from the Prospective Metabolism Islet Cell Evaluation (PROMISE) cohort (n = 418) from 4 separate evaluations over 9 years. Insulin sensitivity was assessed using Matsuda's insulin sensitivity index (ISI) and the homeostasis model assessment of insulin sensitivity (HOMA2_S). Beta cell function was determined using the insulinogenic index divided by HOMA insulin resistance (IGI/IR) and the Insulin Secretion-Sensitivity Index-2 (ISSI-2). Baseline serum fatty acids (mol%) were analyzed using gas chromatography flame-ionization detection. Longitudinal associations were analyzed using covariate-adjusted generalized estimating equations with false discovery adjusted P values.

RESULTS

In the phospholipid (PL) pool, 15:0 was positively associated with logISSI2 (β = 6.54, CI: [2.84, 10.37], p < 0.01) and logIGI/IR (β = 14.75, CI: [6.92, 23.15], p < 0.01), and significantly inversely associated with logGlucose120 (β = -3.45, CI: [-5.63, -1.22], p < 0.05) and logGlucose Area Under the Curve (AUC) (β = -2.84, CI: [-4.38, -1.40], p < 0.01). Trans-16:1n9was significantly associated with logISI (β = 8.08, CI: [2.06, 14.45], p < 0.05) and inversely associated with logGlucose120 (β = -3.11, CI: [-5.50, -0.66], p < 0.05) and logGlucoseAUC (β = -2.16, CI: [-3.75, -0.55], p < 0.05).

CONCLUSIONS

Our findings extend the literature on the potential role of dairy derived saturated and trans conjugate fatty acids in cardiometabolic phenotypes underlying T2DM, specifically in the PL fraction.