High blood sugar levels.
Hyperglycemia, or high blood sugar, occurs when there is not enough insulin in the body and leads to the common symptoms of diabetes.
When your blood sugar levels are high, your blood becomes thick and syrupy. This requires your heart to pump harder to push the blood around your body. This extra work puts strain on your heart and can damage your blood vessels. High blood sugar levels can also lead to the formation of blood clots. These clots can break off and block or break the small blood vessels in different parts of your body. Prolonged high blood sugar levels lead to the complications of diabetes.