Comparison of fatty acid proportions in serum cholesteryl esters among people with different glucose tolerance status: the CoDAM study

Altered fatty acid patterns in blood may be associated with insulin resistance and related disorders. We investigated whether serum proportions of cholesteryl fatty acids and desaturase activity are associated with glucose tolerance status and insulin resistance.

Data were obtained from a cross-sectional study among 471 Dutch participants aged ≥40 years. Individual fatty acids in serum cholesteryl esters were determined and endogenous conversions by desaturases were estimated from product-to-precursor ratios. Proportions of fatty acids were compared among participants with normal glucose tolerance, impaired glucose metabolism and newly diagnosed type 2 diabetes. Partial Spearman correlation coefficients between fatty acids and homeostasis model assessment-insulin resistance (HOMA-IR) were calculated. Adjustments were made for lifestyle and nutritional factors. The proportions of total saturated, mono-unsaturated, trans- and poly-unsaturated fatty acids did not differ significantly between groups, but several individual fatty acids did; the proportions of C18:0 and C20:3n6 were higher, whereas those of C18:1n7 and C20:4n6 were lower in participants with type 2 diabetes compared with those with normal glucose tolerance. Activity of Δ5-desaturase, that is, ratio of C20:4n6 to C20:3n6, was lower (p < 0.01) in participants with type 2 diabetes (7.4) than with normal glucose tolerance (8.4). HOMA-IR was correlated positively with Δ9-desaturase activity (r = 0.11, p < 0.01) and inversely with Δ5-desaturase activity (r = -0.21, p < 0.01).

The observed lower Δ5-desaturase activity in participants with type 2 diabetes and its inverse association with HOMA-IR suggest that changes in fatty-acid metabolism may play a role in the aetiology of type 2 diabetes.