Elevated free fatty acid level is associated with insulin-resistant state in nondiabetic Chinese people

Abstract

Background

Free fatty acids (FFAs) are associated with insulin secretion and insulin resistance. However, the associations among FFAs, obesity, and progression from a normal to a prediabetic state are unclear.

Methods

Nondiabetic subjects (5,952) were divided in two groups according to their body mass index (BMI): obese subjects (BMI ≥24 kg/m²) and nonobese subjects (BMI <24 kg/m²). Clinical and multiple glucolipid metabolism data were collected. The homeostasis model assessment for insulin resistance (HOMA-IR) and β-cell function (HOMA-β) was used. HbA1c level between 5.7% and 6.4% was considered prediabetic. Nonparametric tests, one-way ANOVA, and linear correlation analysis were performed. R and SPSS 23.0 software programs were used to analyze the results.

Results

A U-shaped relationship between FFAs and HOMA-IR was observed. After adjusting for potential confounders, the turning points of FFA levels in the curves were 0.54 mmol/L in the nonobese group and 0.61 mmol/L in the obese group. HOMA-IR levels decreased with increasing FFA concentrations before the turning points (regression coefficient [β]= – 0.9, P=0.0111, for the nonobese group; β=0.2, P=0.5094, for the obese group) and then increased (β=0.9, P=0.0069, for the nonobese group; β=1.5, P=0.0263 for the obese group) after the points. Additionally, our study also identified that FFAs were associated with the prediabetes status in obese individuals.

Conclusion

FFA levels were associated with insulin resistance in nondiabetic subjects, and HOMA-IR in nonobese individuals was more sensitive to FFA changes. Monitoring and controlling plasma FFA levels in obese subjects is significant in decreasing insulin resistance and preventing diabetes.

Keywords:

• FFA
• insulin resistance
• T2DM
• obesity
• HOMA-IR

Supplementary material

Figure S1 Nonlinear relationship between FFA concentration and HOMA-β in the nonobese group (Group 1) and the obese group (Group 2).

Notes: After adjusting for HDL-C, LDL-C, TC, and TG, there was no significant correlation between FFA concentrations and HOMA-β.
Abbreviations: FFA, free fatty acid; HDL-C, high-density lipoprotein; HOMA-β, homeostasis model assessment of β-cell function; LDL-C, low-density lipoprotein; TC, total cholesterol; TG, triglyceride.

Acknowledgments

This study was funded by the National Natural Science Foundation of China (grant number: 81571625). Writing support was provided by International Science Editing.

Disclosure

The authors report no conflicts of interest in this work.