Stroke and Diabetes Mellitus
Approximately 10.3 million Americans have been diagnosed with diabetes mellitus (diabetes). A full 90% of them have diabetes type 2, which occurs later in life and is associated with obesity and physical inactivity. The incidence of type 2 diabetes increases dramatically for adults greater than 40 years of age and continues to increase through your 80’s. Diabetes is an independent risk factor for cardiovascular disease. Mortality from stroke is almost 3 times higher in patients with diabetes than those without. The risk of stroke due to diabetes is higher in Asians, Blacks, and Hispanics.
Diabetics are at increased risk for blood clots as well as a reduced ability to break down blood clots. They also tend to have an increased inflammatory response. Diabetes increases the likelihood of narrowing and hardening of small blood vessels, called small vessel disease. This can lead to blockages of small arteries in the brain and subsequent stroke. Although small vessel disease tends to cause small strokes, survivors of small vessel strokes are more likely to have recurrent strokes and develop cognitive impairment.
Diabetes also increases the narrowing of large vessels feeding the brain such as the carotid artery. Diabetes also seems to lead to accelerated rates of heart failure. Heart failure can lead to slower blood flow and increased clot formation in the cardiac chambers. These clots can break off and move to the brain, causing large strokes.
Strict control of blood glucose has not been shown to reduce the risk of stroke in persons with diabetes. Despite this, vigorous management of diabetes and careful identification and treatment of related risk factors, especially hypertension, remain the fundamental approach for stroke prevention in diabetics. Life style changes, such as improved diet and enhanced exercise are also used to reduce risk. The Mediterranean diet in particular may improve carbohydrate metabolism with significant reductions in plasma glucose, serum insulin and less insulin resistance.
Type 2 diabetes can be measured by a blood test such as hemoglobin A1C (HbA1C) and fasting plasma glucose. HbA1C is a good indicator of how well the blood sugar has been controlled over the previous 30 days. In general, an HbA1C score below 5.7% is considered normal; 5.7% to 6.9% with fasting plasma glucose of 100mg/dL to 126 mg/dL is pre-diabetic; and 7% or greater with fasting plasma glucose more than 126mg/dL is diabetes. Medical treatment for diabetes mellitus is recommended for those with consistent HbA1C of 7% and higher.
 Smith NL, Barzilay JE, Kronnal R, et al. New-onset diabetes and risk of all-cause and cardiovascular mortality. Diabetes Care 2006;29(9):2012-2017.
 Bierman EL, Arthrogenesis in diabetes, Arterioscler Thromb. 1992;12:647-656.
 Fulsom AR et al. for the atherosclerosis risk in communities (ARIC) study investigators. Relation of carotid artery wall thickness to diabetes mellitus, fasting glucose and insulin, body size, and physical activity. Stroke 1994;25:66-73.
 Kuller LH et al. Diabetes Mellitus: Subclinical cardiovascular disease and risk of incident cardiovascular disease and all-cause mortality. Artheroscler Thromb Vasc Biol. 2000;20:823-829.
 Esposito K, Margella R, Ciotola M, et al. Effect of a Mediterranean-style diet on endothelial dysfunction and markers of vascular inflammation in the metabolic syndrome: A randomized trial. JAMA, 2004;292(12):1440-1446.
 2017 VA/DoD clinical practice guidelines for the management of type 2 diabetes mellitus in primary care.