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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 7  |  Issue : 11  |  Page : 16-20

Diabetes as a risk factor for ischemic stroke in a tertiary health care center, Abuja


Department of Medicine, University of Abuja Teaching Hospital, Abuja, Nigeria

Date of Web Publication3-Jul-2018

Correspondence Address:
Gerald Awele Onwuegbuzie
Department of Medicine, University of Abuja Teaching Hospital, Abuja
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/nnjcr.nnjcr_39_16

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  Abstract 


Background: Stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. Stroke has many risk factors, prominent among which is diabetes mellitus (DM); a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action or both. Hyperglycemia may arise in people with acute ischaemic stroke in previously diabetic patients as well as those without a previous history of diabetes. Given the importance of diabetes as a modifiable risk factor for stroke, we decided to study the prevalence of diabetes among Nigerians with stroke. Methods: Samples of random blood sugar and fasting blood sugar were collected from 120 patients with Ischaemic Stroke admitted into the medical ward, however only the fasting blood glucose sample were used. Ischaemic stroke was confirmed clinically using WHO criteria and radiologically by cranial computed tomography scan or MRI were included in this study. Results: There were 66 (55%) male patients with Ischaemic stroke and females 54 (45%). Their ages range from 30-90 years, out of which majority 68 (57%) was between 50 and 69 years of age. In our study, we found 66 (55%) of the patients had fasting hyperglycaemia; 42 (35%) were newly diagnosed while 24 (20%) were previously known diabetics. Conclusion: It is well known that diabetes mellitus is a risk factor and may contribute to stroke; therefore effort should be made at screen patient with diabetes in our clinics. This is particularly pertinent since some of patients with diabetes were only diagnosed after stroke.

Keywords: Diabetes, risk factor, and stroke


How to cite this article:
Onwuegbuzie GA, Reng RS. Diabetes as a risk factor for ischemic stroke in a tertiary health care center, Abuja. N Niger J Clin Res 2018;7:16-20

How to cite this URL:
Onwuegbuzie GA, Reng RS. Diabetes as a risk factor for ischemic stroke in a tertiary health care center, Abuja. N Niger J Clin Res [serial online] 2018 [cited 2021 Jul 25];7:16-20. Available from: https://www.mdcan-uath.org/text.asp?2018/7/11/16/235860




  Introduction Top


Stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. In Nigeria, stroke constitutes about 2.4% of all emergency admissions with cerebral infarction making up 49% of all cases.[1] There are well-established risk factors for stroke, such as increased blood pressure, increased blood cholesterol, cigarette smoking, carotid stenosis, diabetes mellitus (DM), atrial fibrillation, and valvular heart disease. There is a reasonably reliable evidence to suggest that 60%–80% of all ischemic strokes can be attributed to these risk factors.[2]

DM which is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both is a very prominent modifiable risk factor for stroke. Cerebral glucose content controlled by glucose transporters is important to maintain the energy supply in the brain; thus, abnormal blood glucose levels are crucial in terms of stroke morbidity and mortality. Hyperglycemia in acute stroke may arise in previously diagnosed diabetic patients or those without a previous history of diabetes, as a stress reaction resulting from increased production of stress hormones such as cortisol and epinephrine.

Diabetic patients more often develop ischemic strokes and have an increased proportion of lacunar strokes that may be clinically silent.[3] Diabetes may lead to systemic and intracranial atherosclerotic disease which contributes to the changes seen in the cerebral blood vessel.[4] Insulin resistance and hyperinsulinemia, which have been found to contribute to atherosclerotic changes in the blood vessels independently may cause stroke.[5] Patients with diabetes are 1.5 to three times at the risk of stroke compared with the general population[6],[7] A fasting plasma glucose level over 5.5 mmol/L is strongly linked with ischemic cerebrovascular events in patients with preexisting atherothrombotic disease,[8] and stress hyperglycemia following a primary stroke increases the probability of a poor outcome.[9] The presence of diabetes is associated with significantly greater permanent neurological and functional disability and longer hospital stay.[10],[11] Therefore, there is evidence to suggest that glucose-lowering treatment improves clinical outcome in patients with acute ischemic stroke.

Previously, the Framingham study found a 2.5-fold incidence of ischemic stroke in men with DM and a 3.6-fold one in women with DM;[12] and in Bayelsa state, Nigeria, the incidence and pattern of stroke reveals that about 10.7% of all stroke patients are diabetics.[13]

Given the importance of diabetes as a risk factor for stroke in the Nigerian population, we decided to study the frequency of hyperglycemia in adult patients with ischemic stroke.


  Methodology Top


Study location and data collection

The study was carried out at the University of Abuja Teaching Hospital, a tertiary health centre, from June 2012 and June 2015. It is a retrospective study. A total of one hundred and forty patient records were accessed from the medical records of the Stroke unit of the Neurology division of Department of Medicine, University of Abuja Teaching Hospital, Gwagawalada.

Ischaemic stroke was confirmed clinically using WHO criteria and radiologically by cranial computed tomography scan or MRI were included in this study. All patients had full clinical assessment and investigations done including fasting blood glucose. Initial blood glucose on admission was obtained, however the repeat fasting blood glucose use for analysis were subsequent obtained after eight hours of fasting. One-twenty patients had complete data in terms of repeat fasting blood glucose for analysis.

Fasting blood glucose critical level

Inclusion criteria

A hundred and forty patients between 30 to 100 years of age who were admitted by into the medical ward with stroke. All patients who had full clinical assessment for Ischaemic stroke using the WHO criteria and verified radiologically by cranial computer tomography scan from June 2012 to June 2015 were included in the study.

Exclusion criteria

PPatients who had hemorrhagic stroke, transient ischaemic attack, those with space occupying lesion with neurological deficits or metastatic disorder and those Human immunodeficiency Virus (HIV) were excluded from this study.

Data analyses

Statistical analysis of data collected was performed using Analyse-it v4.5 statistical software for Microsoft Excel (Analyse-it, Leeds-UK). Data collected was analysed by frequency, mean, standard deviation and chi-square test. For all statistical tests, the threshold of significance is fixed at 5%. P-value >0.05 indicates non- significant results. P-value <0.05 indicates significant results.


  Results Top


Age and sex

A total of 120 patients were included in the study out of which majority 68 (57%) was between 50 and 69 years of age and there were more male patients 66 (55%) with Ischaemic stroke, than females 54 (45%).

Generally, the age distribution of patients were not normally distributed Shapiro-Wilks (W = 0.97, P = 0.009). The overall mean age of patient is 59.9 ± 13.1 years, but mean age for male is 58.9 ± 11.6 years, while female is 61.0 ± 14.7 years. There is no significant difference between sexes of Ischaemic stroke patients with high levels of FBG (P = 0.3653) [Table 1].
Table 1: Age and sex of distribution of ischemic stroke patients with normal level and diabetes (fasting blood glucose ≥7.0 mmol/L)[14]

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FBG Parameters in Ischaemic stroke patients

Profile FBG at critical value = 7.0 mmol/L. Irrespective of age, while there is no significant difference between sexes, there is generally a significant difference (P < 0.00) between the mean values of High (12.3 mmol/L) and normal (5.7 mmol/L) of FBG in Ischaemic stroke patients.

There is a significant statistical difference between the patients with high FBG and those with normal FBG (P < 0.0001).

Distribution of FBG by category in Ischaemic stroke patients

The mean concentrations are normal FBG = 4.9 ± 0.4 mmol/L, impaired FBG = 6.2 ± 0.4 mmol/L, and abnormal FBG = 12.3 ± 5.2 mmol/L [Table 2].
Table 2: Distribution of FBG by category in Ischaemic stroke patients

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In the female FBG by category in ischemic stroke patients, mean concentration for abnormal FBG = 13.1 ± 6.0 mmol/L, while that of the male is 11.6 ± 4.5 mmol/L and was not statistically significant (P = 0.26) [Table 3].
Table 3: Blood Glucose critical level[14]

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FBG parameter by gender in patients with ischaemic stroke

The FBG parameters by gender in ischemic stroke patients with normal FBG ranged between 4.5 and 5.3 mmol/L, impaired fasting glycemia ranged between 5.8 and 6.6 mmol/L, and abnormal FBG ranged between 7.1 and 17.5 mmol/L. The mean concentration of the impaired and abnormal FBG is higher in females 6.3 ± 0.4 mmol/L and 13.1 ± 6.0 mmol/L than males with 6.1 ± 0.4 mmol/L and 11.6 ± 4.5 mmol/L, respectively [Figure 1].
Figure 1: Fasting blood glucose parameter by gender in patients with ischemic stroke

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  Discussion Top


Ischemic stroke is an important cause of morbidity and mortality worldwide, and currently, a leading cause of disability and death in Nigeria. Studies have shown a higher prevalence of ischemic stroke in patients with DM. Hyperglycemia plays an important pathogenetic role in neuronal damage in acute ischemic stroke and indicative of poorer prognostic factor.

In our study, patients with ischaemic stroke were significantly older and we found that 67.9% of the patients where between age 50-80 years. This finding is similar to previous studies that showed that three-quarters of all stroke cases occur in older individuals[15] and that old age is important risk factor for ischemic stroke.[16],[17] For each successive 10 years after age 55, the stroke rate more than doubles in both men and women.[18],[19] Stroke incidence rates are 1.25 times greater in men, but because women tend to live longer than men, more women than men die of stroke each year. In our study, we observe hypertension in 71.6% of the patients constituting the major risk factors in ischemic stroke. These findings are in keeping with works done in different areas of the world.

In our study, we found that overall ischemic stroke was higher in males than females and even among those with ischemic stroke and diabetes (male – 55.6%, Female – 44.4%) but this was not statistical significant. This is in variance with previous studies which suggested that the cause of higher stroke incidence among men could be related to genetic factors or could be due to the positive effect of estrogen on cerebral circulation.[20] Other researchers have found that women who had stroke were likely to have parental history of stroke than in men.[21] The positive effects of ovarian estrogen effects on the cerebral circulation may protect against ischemic stroke and have been found to cease after menopause.[22],[23],[24] Considering that 67.9% of the patients studied were between 50 and 80 years of age may be a reason for this discrepancy. Some studies have shown that type 2 diabetes may have a stronger effect on stroke risk in women.[25],[26]

In our study, we also found abnormal fasting blood sugar in 55% (66) of our study sample. Furthermore, 20% (24) of those with abnormal fasting blood sugar were previously known to be diabetic whereas 35% (42) were newly diagnosed diabetic. This finding is similar to that by Owolabi et al. who found 44.7% of patients unaware of their diabetic status before hospitalization.[27] Also this finding was consistent with the results of other studies that have found type 2 diabetes to be an important risk factor for stroke.[28],[29],[30] In Nigeria, Ogunrin et al. found that 26.25% of the stroke patients were diabetic as compared to controls of 12.5%.[31] Ekeh et al. found 31.7% prevalence of diabetes in stroke patients.[32] Worth of note is that although diabetes is risk factor for stroke, 35% of those with abnormal blood glucose in the diabetic range were only diagnosed after the stroke. Ogbera et al. in their study found 23% of stroke patients with the diagnosis of diabetes after stroke.[33] This may have been due to poor access to care and lack of routine check of blood glucose which characterize many developing countries either due to poverty of knowledge or financial constrain. In addition to the role of glucose status, there are other aspects of glucose metabolism that may play a role as a risk factor for ischemic stroke specifically hyperinsulinemia and increased insulin resistance which have been shown to be risk factors for ischemic stroke among individuals with normal glucose status [Figure 2].[34]
Figure 2: Fasting blood glucose profile in ischemic stroke patients by critical value[14]

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More disturbing is that the development of microvascular and macrovascular complications of diabetes from prolonged hyperglycemia has not shown that intensive glucose-lowering treatment will improve stroke prevention among diabetics.[35] However, there is evidence suggesting that that glucose-lowering treatment improves clinical outcome in patients with acute ischemic stroke.


  Conclusion Top


It is well known that diabetes mellitus is a risk factor and may contribute to stroke; therefore effort should be made at screen patient with diabetes in our clinics. This is particularly pertinent since some of patients with diabetes were only diagnosed after stroke. Hyperglycemia is considered to be associated with poor outcomes in ischaemic stroke by promoting further brain ischemia therefore blood glucose should be monitored in patients with stroke.

Limitation

Our study is limited by its hospital-based retrospective nature that lacks certain specific data which are not retrievable; however, this does not compromise the essential data. We did not also evaluate their serum hemoglobin A1c (HbA1c) which would have given a better picture, especially for those who are newly diagnosed diabetes after stroke. This will be included in our future study. Despite these limitations, the study is still relevant in our everyday practice.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Shinozaki K, Naritomi H, Shimizu T, Suzuki M, Ikebuchi M, Sawada T, et al. Role of insulin resistance associated with compensatory hyperinsulinemia in ischemic stroke. Stroke 1996;27:37-43.  Back to cited text no. 34
    
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    Tables

  [Table 1], [Table 2], [Table 3]



 

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