Prevalence of diabetes and its effects on stroke outcomes: A meta-analysis and literature review

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Prevalence of diabetes and its effects on stroke outcomes: A meta-analysis and literature review

Lik-Hui Lau, Jeremy Lew, Karen Borschmann, Vincent Thijs, Elif I Ekinci

First published: 16 September 2018

https://doi.org/10.1111/jdi.12932

Citations: 112

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Abstract

Aims/Introduction

Diabetes mellitus is an established risk factor for stroke and maybe associated with poorer outcomes after stroke. The aims of the present literature review were to determine: (i) the prevalence of diabetes in acute stroke patients through a meta-analysis; (ii) the association between diabetes and outcomes after ischemic and hemorrhagic stroke; and (iii) to review the value of glycated hemoglobin and admission glucose-based tests in predicting stroke outcomes.

Materials and Methods

Ovid MEDLINE and EMBASE searches were carried out to find studies relating to diabetes and inpatient stroke populations published between January 2004 and April 2017. A meta-analysis of the prevalence of diabetes from included studies was undertaken. A narrative review on the associations of diabetes and different diagnostic methods on stroke outcomes was carried out.

Results

A total of 66 eligible articles met inclusion criteria. A meta-analysis of 39 studies (n = 359,783) estimated the prevalence of diabetes to be 28% (95% confidence interval 26–31). The rate was higher in ischemic (33%, 95% confidence interval 28–38) compared with hemorrhagic stroke (26%, 95% confidence interval 19–33) inpatients. Most, but not all, studies found that acute hyperglycemia and diabetes were associated with poorer outcomes after ischemic or hemorrhagic strokes: including higher mortality, poorer neurological and functional outcomes, longer hospital stay, higher readmission rates, and stroke recurrence. Diagnostic methods for establishing diagnosis were heterogeneous between the reviewed studies.

Conclusions

Approximately one-third of all stroke patients have diabetes. Uniform methods to screen for diabetes after stroke are required to identify individuals with diabetes to design interventions aimed at reducing poor outcomes in this high-risk population.

Introduction

Diabetes mellitus is a highly prevalent and growing chronic disease affecting an estimated 415 million people globally in 2015, and is predicted to affect 642 million people by 20401. Given that diabetes is a well-recognized risk factor for neurovascular disease2-4, it is postulated that a significant proportion of stroke inpatients will have comorbid diabetes mellitus. A large, international, multicenter case–control study across 32 countries (n = 26,919) showed that diabetes, defined using a threshold of glycated hemoglobin (HbA1c) of ≥6.5% (48 mmol/mol), was found in 26% of acute stroke inpatients compared with 22% of non-stroke controls. Those with diabetes had higher odds (odds ratio [OR] 1.33, 95% confidence interval [CI] 1.18–1.5) of ischemic stroke compared to those with hemorrhagic stroke (OR 0.72, 95% CI 0.6–0.87)3. Additionally, studies have estimated that approximately 20–33% of acute stroke inpatients may have diabetes3, 5, 6. A problem in the literature remains the lack of consistency in the definition of the diagnosis of diabetes.

A number of studies have shown an association between comorbid diabetes and increased mortality7, 8, length of hospital stay, readmission rates, and poorer functional and rehabilitation outcomes after stroke9-12. In contrast, other studies have reported no significant differences in post-stroke outcomes between people with or without diabetes13, 14.

The best measure of dysglycemia that predicts adverse stroke outcomes is unknown. Some researchers argue that it is the acute or ‘stress’ hyperglycemia; that is, peaks of blood glucose levels during an acute stroke admission, which confers poorer outcomes,15, 16 whereas others propose that it is chronic dysglycemia that drives the pathological processes in stroke patients8, 17. The uncertainty in the literature offers an opportunity for further research to inform best clinical practice.

Compared with fasting blood glucose (FBG), testing of HbA1c has the advantage of providing an average measure of glycaemia over the past 120 days, thereby reducing the potential for misdiagnosis as a result of stress hyperglycemia18. Testing requires only one blood draw and does not require the patient to be fasted, and as such, has the potential to be utilized in the hospital setting for routine screening of diabetes mellitus19. A limitation of the use of HbA1c relates to conditions that affect red blood cell count and the survival time of red blood cells, such as anemia or other hemoglobinopathies18. Previous studies have shown that HbA1c can predict the risk of incident stroke20. With the increasing burden of diabetes, there might be a role for routine HbA1c testing in all people admitted with stroke21 in order to identify and improve glycemic management22, 23.

The aims of the present literature review were: (i) to estimate the prevalence of recognized and unrecognized diabetes in stroke populations from the included studies through a meta-analysis; (ii) to examine the associations of acute hyperglycemia and diabetes and outcomes after ischemic or hemorrhagic stroke; and (iii) to review the value of HbA1c compared with admission serum glucose-based tests in predicting stroke outcomes.