Type 1 Diabetes Disrupts the Heart's Internal Clock—But Not Equally

Your heart doesn't work at the same level of efficiency all day long. Like many parts of your body, your heart follows a built-in 24-hour rhythm called a circadian rhythm. These rhythms help coordinate when heart cells should work harder or slower, and they influence heart rate, pumping strength, and gene activity.

Scientists have long known that the left ventricle—the heart's main pumping chamber—follows these daily patterns. But whether the right ventricle, which sends blood to the lungs, also keeps its own daily rhythm was unknown until now. A new study provides the first evidence that the healthy right ventricle does indeed have robust daily rhythms.

Researchers studied the hearts of mice with Type 1 diabetes and compared them to healthy mice over a full 24-hour cycle. Using echocardiograms (ultrasound imaging of the heart), they found that diabetes disrupted the normal daily function of both the right and left ventricles.

One striking finding: in healthy hearts, heart rate follows a predictable daily pattern. Mice with Type 1 diabetes lost this normal pattern entirely. Additionally, diabetes impaired how well both ventricles pumped blood during their most active periods, and it erased the healthy difference between daytime and nighttime left ventricle function.

Importantly, the effects were not identical in both chambers. The right ventricle showed one pattern of disruption, while the left ventricle showed another, suggesting that Type 1 diabetes can damage the heart's rhythmic control in chamber-specific ways.

To understand why these changes happen, researchers examined the genes that control circadian rhythms in heart cells. The body's master clock genes, called core clock genes, remained relatively intact in diabetic hearts. These genes (Arntl1 and Per2) still showed normal 24-hour patterns in both ventricles.

However, the genes that actually translate the clock signal into heart function—called clock output genes—were severely disrupted. In the right ventricle, these output genes showed dampened rhythms, meaning they didn't switch on and off as strongly as they should. In the left ventricle, these genes showed abnormally amplified rhythms, meaning they switched on and off more dramatically than normal.

This distinction matters: it suggests that in Type 1 diabetes, the heart's inner timekeeping machinery is still running, but the signals it sends to control actual heart function are broken or scrambled.

Heart disease is the leading cause of death in people with Type 1 diabetes—a fact that researchers have struggled to fully explain. This new finding offers one piece of the puzzle: the loss of daily rhythmic control over heart function may make the heart more vulnerable to damage and disease.

The fact that Type 1 diabetes disrupts the right and left ventricles differently suggests that the heart's response to diabetes is complex and chamber-specific. This could explain why some aspects of heart disease develop differently in people with Type 1 diabetes compared to the general population.

While this research was conducted in mice, it provides a foundation for understanding how diabetes alters the heart at a fundamental level. Future studies may reveal how to protect or restore these daily rhythms and reduce heart disease risk in people with Type 1 diabetes.

Source: Function (Oxford, England). Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.