Abstract
Little is known about the longitudinal association between fasting glucose (FG) and the diurnal cortisol profile among those with normal fasting glucose (NFG), impaired fasting glucose (IFG) and diabetes. To assess the temporality of the relationship between cortisol and glucose, we examined the association of: A) change (Δ) in diurnal cortisol curve features with ΔFG; B) prior annual percent change in FG with diurnal cortisol curve features; and C) baseline cortisol curve features with ΔFG over 6 years among participants with NFG, IFG and diabetes in the Multi-Ethnic Study of Atherosclerosis. The main outcome measures were: A) 6-year ΔFG (n = 512); B) diurnal cortisol curve features (wake-up cortisol levels, cortisol awakening response, total area under the curve, overall decline slope and bedtime cortisol) (n = 1275); and C) 6-year ΔFG (n = 700). After full multivariable adjustment among participants with diabetes, each annual percent change increase in wake-up cortisol, total area under the curve (AUC), and overall decline slope was associated with a significant increase in FG over 6 years in all models (all p < 0.05). A 1% prior annual increase in FG was associated with a 2.8 % lower (-2.8 %; 95 % CI: -5.3 % to -0.4 %) bedtime cortisol among participants with NFG at baseline. A 1 % flatter overall decline slope was associated with a 0.19 % increase in subsequent annual % change in FG over 6 years among participants with diabetes. Among participants with diabetes there was a positive association of change in wake-up cortisol, total AUC and overall decline slope with change in FG. Baseline overall decline slope was positively associated with change in FG among the baseline diabetes group. These results suggest a detrimental role of cortisol contributing to glycemia among individuals with diabetes.