Higher circulating levels of non-esterified fatty acids are associated with faster kidney function decline in post-menopausal women with type 2 diabetes: a pilot prospective study

Aims Currently, there is little and inconsistent evidence regarding the possible adverse effects of circulating levels of non-esterified fatty acids (NEFA) on kidney function decline in patients with type 2 diabetes mellitus (T2DM).Methods We followed for a median of 4.6 years 85 post-menopausal women with non-insulin-treated T2DM and preserved kidney function at baseline. Serum NEFA concentrations were measured using an enzymatic colorimetric method. Glomerular filtration rate (eGFR) was estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.Results Enrolled patients had a baseline mean eGFRCKD-EPI of 83 +/- 12 mL/min/1.73 m(2) and a median serum NEFA concentration of 662 uEq/L (interquartile range 524-842 uEq/L). During the follow-up period, 13 patients developed kidney function decline at follow-up (defined as an eGFRCKD-EPI decline >= 30% from baseline). In Cox proportional hazards regression analyses, higher serum NEFA levels were significantly associated with an increased risk of developing kidney function decline (adjusted-hazard ratio 3.67, 95% CI 1.64-8.22, p < 0.001; for each 1-SD increment, i.e., 262 uEq/L), even after adjustment for waist circumference, hemoglobin A1c, C-reactive protein, HOMA-estimated insulin resistance, hypertension, dyslipidemia, microalbuminuria, baseline eGFR(CKD-EPI), as well as temporal changes in HbA1c levels or the use of renin-angiotensin system inhibitors over the follow-up.Conclusions The findings of this exploratory prospective study show that in post-menopausal women with T2DM and preserved kidney function at baseline, higher circulating levels of NEFA were strongly associated with a faster kidney function decline, even after adjustment for established renal risk factors and potential confounders.