Stroke and Diabetes | Is there a connection?

FACTS and FIGURES

  • Each year nearly 800,000 people experience a new or recurrent stroke
  • A stroke happens every 40 seconds and every 4 minutes someone dies from stroke
  • Stroke is a leading cause of death worldwide and the most common cause of long-term disability amongst adults, more particularly in individuals with diabetes mellitus and arterial hypertension
  • Up to 80 percent of strokes can be prevented

Recently I received a query from a gentleman whether diabetes mellitus (DM) and stroke are associated with each other. In this article I am going to discuss about interrelation between DM and stroke.

Diabetes causes several microvascular and macrovascular changes which leads to many clinical complications including stroke. Macrovascular complications  are coronary artery disease, peripheral arterial disease, and stroke while microvascular complications  are diabetic nephropathy, neuropathy, and retinopathy.

DM is an important risk factor for stroke. Many subjects diagnosed with DM may suffer from all types of stroke. So, it is very important to understand what are the different types of stroke.

DM can cause pathologic changes in the blood vessels at various locations which can lead to stroke. If an individual with uncontrolled glucose level suffer from stroke, in that case, post stroke outcomes are very poor and chances of mortality increases. Initial strokes as well as recurrence of stroke recurrence can be easily prevented by controlling blood sugar levels and other associated risk factors.

What is stroke and what are different types of stroke?

I am sure most of you must have heard about stroke. So, what exactly is stroke? How does it occur?

As mentioned in the National Stroke Association, stroke simply means “brain attack” which can happen to anyone at any time. “It occurs when blood flow to an area of brain is cut off. When this happens, brain cells are deprived of oxygen and begin to die. When brain cells die during a stroke, abilities controlled by that area of the brain such as memory and muscle control are lost.”

Basically, there are two types of strokes:

  1. Ischemic stroke
  2. Hemorrhagic stroke

An ischemic stroke can occur in two ways, a) embolic stroke and b) thrombotic stroke. Hemorrhagic stroke can be further divided into two types a) intracerebral hemorrhage and b) subarachnoid hemorrhage.

What is the connection between diabetes mellitus and stroke?

Diabetes mellitus is an independent risk factor for stroke with a 2-fold increased risk in stroke for subjects diagnosed with DM. Stroke accounts for approximately 20% of deaths in individual with DM. Pre-diabetics are also at increased risk of stroke.

A review article which was published in The American Journal of the Medical Sciences discusses about the pathophysiology of stroke in subjects with DM. According to the article there could be several mechanisms wherein DM leads to stroke. A very nice schematic diagram is presented in this article. If you want to know more about it, you can check the full text article by clicking the link above.

Individuals with type 2 diabetes  mellitus (T2DM) have stiffer arteries and decreased elasticity as compared with subjects having normal glucose level. Arterial stiffness together with systemic inflammation in subjects with DM leads to atherosclerosis which can further lead to stroke.

Vascular endothelial function is critical for maintaining structural and functional integrity of the vessel walls as well as the vasomotor control. Nitric oxide (NO) mediates vasodilation, and its decreased availability can cause endothelial dysfunction and trigger a cascade of atherosclerosis due to which an individual can have a stroke. Individuals with DM are more prone to congestive heart failure due to hypertension, microvascular disease, lipid abnormalities like high cholesterol. All these factors are responsible for stroke.

If DM in not controlled, then there is high risk for both ischemic as well as hemorrhagic strokes. There are specific clinical patterns of ischemic stroke in individuals with DM. For example, individuals with DM are more likely to have limb weakness and dysarthria which means difficult or unclear articulation of speech that is otherwise linguistically normal.

Risk factors for diabetes mellitus and stroke 

There could be one more reason for ta strong connection between DM and stroke is that some of the risk factors for stroke are also the risk factors for DM. 

  • Stroke occurs twice as often in people with diabetes compared to people without diabetes
  • In most hospitalized series of stroke victims, up to 20% of subjects have DM
  • Hypertension is the most important risk factor for stroke, even among diabetic patients
  • Dyslipidemias are a strong risk factor for atherosclerotic disease but are of lesser importance in stroke compared to coronary artery disease
  • Other well-known lifestyle risk factors for arterial disease and stroke include
    • tobacco smoking
    • sedentary lifestyle
    • obesity
    • high-fat and high-sodium diet
    • elevated serum homocysteine
    • alcohol abuse
    • sympathomimetic drug use (cocaine, ecstasy, nasal decongestants)
    • stress

How to manage high blood glucose level or hyperglycemia?

The use of combined behavioral modification and medical therapy in diabetics has been shown to reduce the risk of stroke.

Proper management of post stroke hyperglycemia is important for improving outcomes, as hyperglycemia is associated with poor outcomes.

The American Heart Association (AHA)/ American Stroke Association guidelines for the early management of subjects with acute ischemic stroke recommends “to achieve serum glucose concentrations in the range of 140– 180 mg/dL (7.8–10 mmol/L) during the first 24 hours after acute ischemic stroke in all hospitalized patients.” The European Stroke Initiative guidelines also recommend “blood glucose of 180 mg/dL (10 mmol/L) or higher justifies immediate insulin titration.”

However, aggressive management of hyperglycemia in diabetics has not been shown to decrease the incidence of stroke and may actually be harmful.

The Action to Control Cardiovascular Risk in Diabetes Study (ACCORD) compared intensive glucose lowering to a goal glycated hemoglobin (HbA1c) level below 6%, versus liberalized goals of 7 – 7.9%, and found no difference in stroke incidence. In contrast, a statistically significant increase in overall mortality in the intensive management group was observed.

The results suggest that it may be that the greatest effects of hyperglycemia on stroke risk accumulate early in the course of the disease and in the prediabetes stage, rather than late in the course when co-morbid cardiovascular risk factors are more likely to be present.

Conclusion

Now we know that DM is an important modifiable risk factor for stroke, especially ischemic strokes and is associated with poorer outcome. The optimal management of the milder forms of hyperglycaemia associated with acute stroke is unknown. Aggressive glucose control through lifestyle change or medications and modification of other associated risk factors (such as BP and dyslipidemia) are critical steps toward effective stroke prevention.

If you liked this article, please click the like button and share it with your friends and family to make them understand the connection between DM and stroke. If you have any comments, please type in the Leave a Reply box and I will surely try to answer you query.

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Anupam Ghose, a physician by training, was diagnosed with Type 2 Diabetes Mellitus (T2DM) in 2017. After the diagnosis of T2DM he followed a low carbohydrate high fat (ketogenic) diet and reversed his T2DM within a year. Now he is on a mission to educate people and spread awareness about T2DM. Since he could reverse his T2DM following ketogenic diet, now he is  doing extensive research on ketogenic diet and expanding his knowledge on this particular topic. His main goal is to make people understand that the conventional method of treating T2DM is incorrect and it is very much possible to reverse T2DM through diet and lifestyle modification.

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