Sex-dependent association between erythrocyte n-3 PUFA and type 2 diabetes in older overweight people

The association between n-3 PUFA intake and type 2 diabetes (T2D) is unclear, and studies relating objective biomarkers of n-3 PUFA consumption to diabetic status remain limited. The aim of this study was to determine whether erythrocyte n-3 PUFA levels (n-3 index; n-3I) are associated with T2D in a cohort of older adults (n 608). To achieve this, the n-3I (erythrocyte %EPA + %DHA) was determined by GC and associated with fasting blood glucose; HbA1c; and plasma insulin. Insulin resistance (IR) was assessed using the homeostatic model assessment of insulin resistance (HOMA--IR). OR for T2D were calculated for each quartile of n-3I. In all, eighty-two type 2 diabetic (46.3% female; 76.7 (SD 5.9) years) and 466 non-diabetic (57.9% female; 77.8 (SD 7.1) years) individuals were included in the analysis. In overweight/obese (BMI >= 27 kg/m(2)), the prevalence of T2D decreased across ascending n-3I quartiles: 1.0 (reference), 0.82 (95% CI 0.31, 2.18), 0.56 (95% CI 0.21, 1.52) and 0.22 (95% CI 0.06, 0.82) (P-trend = 0.015). A similar but non-significant trend was seen in overweight men. After adjusting for BMI, no associations were found between n-3I and fasting blood glucose, HbA1c, insulin or HOMA-IR. In conclusion, higher erythrocyte n-3 PUFA status may be protective against the development of T2D in overweight women. Further research is warranted to determine whether dietary interventions that improve n-3 PUFA status can improve measures of IR, and to further elucidate sex-dependent differences.