Diabetes is a major risk factor for stroke. Excessive levels of glucose (blood sugar) or insulin (a hormone that helps regulate glucose) in the bloodstream can damage the arteries that deliver oxygen to the brain. Hyperglycemia and hyperinsulinemia may also increase the risk of stroke in people with prediabetes or high-normal glucose.

In addition, diabetic individuals are also more liable to exhibit the following risk factors for stroke:

• High blood pressure. Studies indicate that individuals with high blood pressure (hypertension) are four to six times more likely to have a stroke than those with normal blood pressure. The National Diabetes Education Program estimates that 70 percent of people with diabetes have high blood pressure. New research indicates that low blood pressure (hypotension) may also increase the risk of stroke in people with chronic kidney disease, such as diabetic nephropathy or end-stage renal disease.
  
  
• Vascular diseases. People with diabetes are more likely than nondiabetics to have diseases of the blood vessels such as atherosclerosis, peripheral arterial disease, cerebrovascular disease, carotid artery disease or coronary artery disease.
  
  
• Heart conditions. Heart disease is the leading cause of death in people with diabetes. Conditions that are more common with diabetes and that raise the risk of stroke include: heart attack, heart failure and atrial fibrillation, a condition in which the two upper chambers of the heart quiver rather than beat effectively.
  
  
• Unhealthy levels of cholesterol and triglycerides. Hyperlipidemia, which is common among diabetic individuals, is a chief contributor to atherosclerosis (a condition characterized by excess plaque on the inner arterial walls) and stroke.

  

• Obesity. Being severely overweight is a major risk factor for type 2 diabetes and stroke.
  
  
• Inadequate exercise. Although regular exercise is one of the cornerstones of diabetes management, many patients do not engage in sufficient physical activity.
  
  
• Hypoglycemia (low blood sugar). Hypoglycemia increases the risk of stroke in older diabetic individuals. Consequently, a physician may advise older adults to treat for hypoglycemia at a higher glucose level than younger patients.
  
  
• Preeclampsia. Diabetes increases a woman’s risk of preeclampsia (high blood pressure and proteinuria during pregnancy). Recent research from the U.S. Centers for Disease Control and Prevention (CDC) shows that preeclampsia raises the risk of stroke in the future as well as during the pregnancy.
  
  
• Gum disease. Recent research associates periodontitis with higher risk for stroke, in addition to its previously established link to heart disease.

• Diabetic retinopathy. This eye disease appears to be an independent risk factor for stroke, according to new research.

Other risk factors associated with stroke include:

• Medical history. A personal history of mini-stroke (transient ischemic attack) or family history of stroke raises an individual’s risk. Genetics can also be a factor. For example, a gene variant LTC4S has been linked to stroke risk in women.
  
  
• Smoking cigarettes. Smokers are three times more likely to have a stroke than non-smokers. Smokers who use certain birth control pills are at even greater risk, according to the American Heart Association.
  
  
• Age. Rates of stroke nearly double in men and women in the general population who are over age 74. Diabetes, including type 1 diabetes and type 2 diabetes, boosts the risk of stroke in early and middle adulthood, recent research indicates.
  
  
• Race. In addition to their higher risk of type 2 diabetes, black Americans are about twice as likely as white Americans to have a stroke. Reasons may include obesity, stress, habits such as diet and smoking, Genetics and the increased risk of sickle cell anemia, an inherited blood disease that can cause a stroke.
  
  
• Sex. Strokes are more common in men but more deadly in women. Stress and the higher rate of diabetes may help explain the greater incidence of stroke in men. Pregnancy, preeclampsia, gestational diabetes, childbirth and menopause are risk factors for stroke in women. Hormonal and other biological reasons and genetics may contribute to women’s poorer outcomes after a stroke.
  
  
• Excessive consumption of alcohol.
  
  
• Drug abuse. This includes cocaine, intravenous drugs and, according to some research, marijuana.
  
  
• Injuries to the head and neck.
  
  
• Sleep apnea. A condition in which an individual’s breathing stops and starts many times during sleep.
  
  
• Carotid artery dissection. A tear in a carotid artery’s inner lining which creates a space between the inner and outer layers. Stroke may occur if blood leaks into this region.
  
  
• Atrial flutter (atrial fibrillation). A type of tachycardia, which is an unusually fast heart rhythm, that originates in the heart’s upper chambers (atria)).
  
  
• Certain surgical or catheter-based procedures.
  
  
• Depression.
  
  
• Air pollution. Previous studies have linked air pollution to risk of heart attack, and recent research suggests a possible connection to stroke risk.

Children can also suffer strokes, but many of these causes and risk factors are much different.