Written by: Pooja Kasarapu
Medically reviewed by: Robert Philibert MD PhD
In one of our past blog posts, we mentioned how being diagnosed with diabetes is a risk factor for developing heart disease ( National Institute of Diabetes and Digestive and Kidney Diseases ). Diabetes increases risk for heart disease through a variety of mechanisms. For example, diabetes affects the blood vessels in the body by making them less flexible and it also interferes with the nerves that signal the heart to pump. The molecular pathways behind those actions are complex.Yet understanding them is critical for appreciating how diabetes and heart disease go hand-in-hand.
Diabetes can be classified as being either Type I or Type II. Type I diabetes is characterized by the body not producing enough insulin. Insulin helps move sugar in the blood into the cells so they may use it for their daily functions. When sugar, the source of energy, is not moved into cells, the person’s cells are deprived of a major source of energy. In Type II diabetes, the body has insulin but is unable to respond to it, which leads to the same consequences as Type I.
Clinicians have a variety of methods through which to test for diabetes. The hemoglobin A1c (HbA1c) assay is a simple blood test that provides a measurement of how well your blood sugar is regulated. However, the results of the HbA1c assay are not alway clear. Sometimes, individuals may appear to have “pre-diabetes”. Pre-diabetes is when an individual has higher than normal glucose levels, but not high enough to be diagnosed with diabetes. Pre-diabetes can develop into diabetes. But if recognized early, sometimes progression to overt diabetes can be prevented.
Why is diabetes a risk factor?
Diabetes is an independent risk factor for heart disease. However, in the presence of other risk factors, it can intensify undesirable effects of those other conditions. There are several common conditions in which the presence of diabetes enhances the disease progression of heart disease. One of them is dyslipidemia (Dokken 2008). Diabetic patients have higher levels of low density lipoproteins (LDLs), which are vesicles (spheres) of fats and protein used to transport lipids in your blood that contain high levels of cholesterol. Those patients with higher levels of LDL are more likely to have narrowed arteries because the cholesterol and other lipids in these vesicles can be entrapped in the walls of the arteries and become oxidized. Oxidation is a chemical reaction that changes a chemical’s properties. Oxidized fats deposited by LDLs unfortunately stimulate responses in the immune system which result in the attraction of leukocytes (a type of white blood cell) (Chan 1998). The activities of these leukocytes increase plaque formation that in turn, can block the flow of blood by narrowing the artery.
Hypertriglyceridemia is another condition frequently observed in diabetic patients (Dokken 2008). The key characteristic of this condition is the presence of high levels of a certain fat called triglycerides, which are made up of up to three molecules of fatty acids (hence “tri”) and one molecule of glycerol. Like glucose, triglycerides can be metabolized to provide energy for the cell and cells need to balance the amount of energy they derive from glucose with that derived from fat. As a consequence, insulin levels not only affect not only the levels of glucose in the blood, but the levels of fatty acids as well.
In healthy individuals, insulin helps to ensure that there are low levels of fatty acids in the blood through the regulation of certain enzymes (Shen 2007). However, diabetic patients may become resistant to insulin or in later stages of illness not have sufficient levels of insulin. Without sufficient insulin “action”, fatty acid levels in the blood rise and can result in the clogging of arteries.
Hypertension is also linked to diabetes (Dokken 2008). In part, this results from diabetic patients having low levels of vasodilators and high levels of vasoconstrictors in the blood. Vasodilators are chemicals in the body that increase the diameter of blood vessels in the body which decreases blood pressure. Vasoconstrictors do the opposite. High blood pressure can be damaging to the walls of blood vessels.
Blood clots are another concern for those with diabetes because clots have the potential to block blood flow (Dokken 2008). Those with diabetes often have higher levels of clotting factors in the blood. One of the most important clotting factors in the blood is fibrinogen. Its name stems from its ability to activate a mechanism in the body where fibers begin to form a mesh at a site where blood clotting is required. The mesh catches red blood cells in its netting which eventually results in aggregation of cells or clot.
Regulating clotting activity is important. For example, people often lacerate their skin resulting in significant bleeding. While blood clotting is favorable in such situations, high levels of clotting could prove to be fatal. Blood must be kept flowing in the body, including near the laceration. But overactivity of the coagulation system may result in the formation of a thrombus, which is a blood clot in a blood vessel which blocks the flow of blood near the site of the laceration or elsewhere in the body. Some thrombi (plural for thrombus) are capable of moving to other locations of the body. If blood clots relocate to places such as the coronary artery or the brain, the patient can face severe side effects.
The risk for diabetes varies with respect to ethnicity and gender. Furthermore, the risk of heart disease from diabetes also varies with gender. After careful consideration of a study published in the journal Circulation, the American Heart Association has stated that women diagnosed with diabetes are more at risk for heart disease than men diagnosed with diabetes. Diabetes also seems to be more prevalent in American Indians/Alaskan Natives and non-Hispanic Blacks according to the American Diabetes Association.
What can I do to stay healthy?
There are several medications that are often prescribed to people with both diabetes and heart disease (Harvard Health Publishing). One of the most common medications is a class of drugs called “statins” which decrease the cholesterol levels. Blood pressure medications are also prescribed since diabetics sometimes have high rates of high blood pressure. Finally, if your doctor feels it is necessary to prescribe medicine at the stage of your disease progression of diabetes, you may receive a prescription for perhaps insulin or an oral medication to encourage your body to respond to insulin.
Exercise is often emphasized as a key factor in maintaining heart health. Dr. Benjamin Scirca, a cardiologist at Harvard-affiliated Brigham and Women’s Hospital, says that exercise “can do both jobs” for a person with both conditions. Exercise can keep the heart in good shape and help regulate blood glucose levels ( Harvard Health Publishing).
The best way to stay healthy for someone suffering from diabetes and heart disease is following the Center for Disease Control’s ABCs:
- A: A1C tests are a great way to monitor your blood glucose levels.
- B: Blood pressure is best kept below 140/90 mm Hg.
- C: Cholesterol levels must be regulated through a balanced diet.
- s: Stop smoking.
For someone with diabetes and who is looking to prevent developing heart disease, it is important to :
- Stop smoking
- Eat a balanced diet
- Have a good sleep schedule
- Maintain a healthy weight
Never hesitate to consult your physician regarding the best action plan for you. Together, you will be able to tailor a treatment plan that can help reduce your risk of suffering severe effects from diabetes and heart disease.
References:
- “Diabetes, Heart Disease, and Stroke,” National Institute of Diabetes and Digestive and Kidney Diseases, https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/heart-disease-stroke
- “The diabetes-heart disease connection and what it means for you,” Harvard Health Publishing, Mar. 2014, https://www.health.harvard.edu/heart-health/the-diabetes-heart-disease-connection-and-what-it-means-for-you
- “Diabetes and Your Heart,” Centers for Disease Control and Prevention, https://www.cdc.gov/diabetes/library/features/diabetes-and-heart.html
- The Pathophysiology of Cardiovascular Disease and Diabetes: Beyond Blood Pressure and Lipids Betsy B. Dokken Diabetes Spectrum Jul 2008, 21 (3) 160-165; DOI: 10.2337/diaspect.21.3.160
- Alvin C. Chan, Vitamin E and Atherosclerosis, The Journal of Nutrition , Volume 128, Issue 10, October 1998, Pages 1593–1596, https://doi.org/10.1093/jn/128.10.1593
- Shen GX: Lipid disorders in diabetes mellitus and current management. Curr Pharm Analysis 3:17 –24, 2007
- “Women with Diabetes at Greater Risk for Heart Disease than Men,” CardioSmart, January 2016, https://www.cardiosmart.org/news/2016/1/women-with-diabetes-at-greater-risk-for-heart-disease-than-men
- “Statistics About Diabetes,” American Diabetes Association, https://www.diabetes.org/resources/statistics/statistics-about-diabetes
- “Facts Bridging the Gap CVD Health Disparities,” American Heart Association, American Stroke Association,
- “Racial/Ethnic Differences in Cardiac Care: The Weight of the Evidence,” The Kaiser Family Foundation and the American College of Cardiology Foundation, Oct. 2002, https://www.kff.org/wp-content/uploads/2002/09/6040r-racial-and-ethnic-differences-in-cardiac-care-report.pdf