Association between 8 a.m. cortisol levels and insulin resistance in healthy individuals from Algiers

Background

Cortisol is a counterregulatory hormone that antagonizes insulin. Its chronic supraphysiological elevation induces insulin resistance, a risk factor for cardiovascular and metabolic diseases. However, the relationship between insulin resistance and normal cortisol concentrations remains controversial. This study evaluates the association between 8:00 a.m. cortisol levels and insulin resistance, as estimated by the HOMA-IR index, and compares the HOMA-IR index with other insulin resistance indices: QUICKI, TyG, and the TG/HDL ratio.

Methods

Healthy adult volunteers were recruited. Exclusion criteria included smoking, pregnancy, and use of lipid-lowering medications, steroids, antidiabetic agents, or antihypertensive agents. Fasting measurements included blood glucose, insulin, cortisol, C-peptide, triglycerides, total cholesterol, LDL cholesterol, HDL cholesterol, and AST. Blood pressure was measured, and a questionnaire on clinical, anthropometric, dietary, and lifestyle data was completed.

Results

Of 77 participants, 6 were excluded due to impaired biochemical status. A significant association was found between the HOMA-IR index and cortisol levels in the upper normative range (≥95.5 μg/L, p < 0.001). This association was also found with BMI, waist circumference, insomnia, sedentary lifestyle, unbalanced diet, and fruit intake, but not for sweets and vegetable intake (p > 0.05). A correlation was confirmed between insulin resistance (assessed by the HOMA-IR index) and other indices such as QUICKI, the TG/HDL ratio and the TyG index.

Conclusion

The QUICKI, TyG and TG/HDL indices are good alternative indicators of insulin resistance, which is more severe in people with cortisol levels in the upper normative range. In addition, a sedentary lifestyle and unbalanced diet also contribute to insulin resistance.