The Role of Circadian Rhythms in the Hypertension of Diabetes Mellitus and the Metabolic Syndrome

Purpose of the Review: Cellular circadian clocks regulate physiological functions during day and night. It has been convincingly demonstrated that hypertension in patients suffering from diabetes mellitus or metabolic syndrome is characterized in most cases by a disturbed 24-h profile resulting in a nondipper pattern. We consider possible correlation between biological clocks and symptoms of the metabolic syndrome. Recent Findings: Changes in circadian clock function have been linked to metabolic disorders in genome-wide association studies. Epidemiological studies have shown that a loss of nocturnal decline in blood pressure increases the risk of cardiovascular morbidity and mortality and end-organ damage. Looking at clock genes, however, there is no obvious association between symptoms of diabetes or metabolic syndrome and clock gene expression. Summary: Emerging data suggest that circadian rhythm disruption is a risk factor for metabolic and cardiovascular disorders, while disease feedback on clock function is limited.