Increased Understanding of Cardiovascular Disease Risk Factors in Youth with Type 1 Diabetes
Two studies of cardiovascular disease (CVD) risk factors in youth with type 1 diabetes provide new information about progression of CVD in this population, and about potential prevention strategies. Type 1 diabetes, like type 2 diabetes, is associated with an array of serious, long‑term complications, including CVD. People with diabetes have a greatly increased risk for CVD, CVD occurs earlier in people with diabetes than in people without diabetes, and CVD is the leading cause of mortality in people with diabetes. Youth with type 1 diabetes will endure a higher lifetime burden of diabetes than adults and, therefore, a higher burden of complications, including CVD. It is not known, however, whether CVD in youth with type 1 diabetes has similar risk factors and/or the same progression to advanced disease as in adults. By studying the natural history of CVD and examining CVD risk factors in youth with type 1 diabetes, scientists from the SEARCH for Diabetes in Youth CVD Study gained insights that could lead to strategies to prevent or treat CVD in this population.
In the first study, SEARCH scientists examined heart rate variability in youth with type 1 diabetes. The autonomic nervous system regulates heart rate, enabling changes in heart rate in response to activity/stress and rest. Reduced heart rate variability is a sign of cardiac autonomic neuropathy, a complication of diabetes that increases the risk of mortality. The researchers found that youth with type 1 diabetes have reduced overall heart rate variability, particularly youth with suboptimal blood glucose control, compared to youth without type 1 diabetes. In the other study, SEARCH scientists examined the “carotid intima‑media thickness” (IMT) of youth with type 1 diabetes. IMT is a measure of the thickness of the arterial wall of the carotid artery, which supplies the head and neck with oxygenated blood. A thickening of the arterial walls can indicate the presence of atherosclerosis. In adults, type 1 diabetes leads to an increase in carotid IMT. In this study, the researchers found that youth with the disease also had increased IMT and that this association may be attributable to poor blood glucose control, compared to youth without type 1 diabetes. Therefore, both heart rate variability and IMT are altered in youth with type 1 diabetes, indicating that this population shows signs of CVD risk early in the course of the disease.
The NIDDK’s Diabetes Control and Complications Trial (DCCT) and its follow‑up study, Epidemiology of Diabetes Interventions and Complications, found that adults with type 1 diabetes who had intensive blood glucose control during the DCCT had about half the rate of CVD events compared to those who received conventional treatment. The SEARCH CVD study has provided novel data about CVD and its risk factors in youth with type 1 diabetes, and the findings continue to suggest the importance of good blood glucose control to prevent CVD in people with the disease.