The Inflammatory Clock: Chronobiology of CRP and Cardiometabolic Risk in Pre-Diabetic Adults

Abstract

Abstract:
Background: Circadian fluctuations in inflammatory biomarkers may influence cardiometabolic risk, yet remain uninvestigated in prediabetes. This study evaluates daily C-reactive protein (CRP) variation and its association with insulin resistance and lipid profiles.
Methods: A cohort of 312 adults with impaired fasting glucose (IFG) from Germany was studied. CRP was measured at 8AM, 2PM, and 8PM on two consecutive days. HOMA-IR and lipid panels were assessed. Chronotype was identified using the Munich ChronoType Questionnaire.
Results: Mean CRP levels peaked at 8PM (2.9 ± 1.4 mg/L) vs. 8AM (1.8 ± 0.9 mg/L; p < 0.001). Evening chronotypes had higher CRP variability and elevated HOMA-IR (3.9 vs. 2.6; p = 0.02). Multivariate regression showed evening CRP elevation independently predicted HOMA-IR >2.5 (OR = 2.81, 95% CI: 1.66–4.71).
Conclusion: CRP demonstrates circadian fluctuation in prediabetic adults, with evening elevation associated with worse insulin sensitivity. Chronobiological monitoring of inflammation could improve cardiometabolic risk stratification.