Diabetes is a lifelong condition of hyperglycemia, which is an elevated blood glucose (sugar) level. Glucose is the main source of energy for the body. However, it requires insulin in order to be absorbed into the cells and utilized. When glucose is left in the blood, it can cause damage to blood vessels and organs, leading to potentially life-threatening complications. The damage caused has a variety of effects on cardiac (heart) functions.
Atherosclerosis
Atherosclerosis is a disease that can affect anyone, but people with diabetes are at an increased risk and the disease often progresses faster. In fact, those with diabetes are two to six times more likely to develop atherosclerosis than non-diabetics, according to information provided by Merck Manual. Atherosclerosis is the narrowing of the arteries due to a buildup of fat, calcium and cholesterol that together form a substance called plaque.
Atherosclerosis begins when the lining of the arteries is damaged, which causes white blood cells to accumulate and form foam cells. These foam cells attract cholesterol and other fatty material that build up into plaque. As plaque builds up, the arteries become narrower and begin to harden. This reduces blood flow to the heart. With reduced blood flow there's less oxygen reaching the heart, causing it to malfunction and possibly result in a heart attack.
Hypertension
Hypertension--or high blood pressure--affects approximately 70 percent of people with diabetes, according to an article published in Nature Clinical Practice: Endocrinology and Metabolism. Diabetes increases blood pressure in a variety of ways, including promoting salt retention, stimulating the sympathetic nervous system that results in adrenaline release and causing abnormal kidney function.
High blood pressure increases the incidence of atherosclerosis. Hypertension also causes the heart to work harder in order to pump blood throughout the body. This extra pressure on the heart can cause the left ventricle to become enlarged, further affecting its ability to pump blood. Over time, added strain on the heart caused by hypertension can weaken the heart muscle and lead to heart failure.
Autonomic Neuropathy
A high level of glucose in the blood can cause nerve damage. The autonomic nervous system is the group of nerves that supply the internal organs, including the blood vessels and the heart. Damage to these nerves, known as autonomic neuropathy, can affect how the heart functions. A loss of nerve function in the small blood vessels can disrupt the regulation of blood flow, affect blood pressure and contribute to hypertension. Damage to the nerves in the heart can affect the rate at which the heart pumps, known as the pulse rate, and cause irregular heart rhythms.
