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 a 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 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 suffers from a 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 a 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 the 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:
- Ischemic stroke
- 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 an 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 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 the 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 is not controlled, then there is a 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 a strong connection between DM and stroke is that some of the risk factors for stroke are also the risk factors for DM.
- A 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 the 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
- high-fat and a high-sodium diet
- elevated serum homocysteine
- alcohol abuse
- sympathomimetic drug use (cocaine, ecstasy, nasal decongestants)
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 poststroke 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%. The study 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.
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 hyperglycemia 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.
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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 diet and reversed his T2DM within a year. Now he has one main goal in life and that is to make people understand that the conventional method of treating T2DM is not beneficial. Type 2 diabetes is reversible and the best way to reverse T2DM is through diet and lifestyle modifications. He now decided to help people with type 2 diabetes by offering online coaching to reverse their diabetes.