Original research
Type 2 diabetes and cardiovascular disease in South Asians

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Abstract

Type 2 diabetes (T2DM) is growing at a pandemic scale and is associated with a rapid increase in its complications such as cardiovascular diseases (CVD). This problem is even worse in South Asian population with South Asian people having a much higher prevalence of T2DM and CVD, occurring at an earlier age and being associated with premature and high mortality. This review looks in detail at the current knowledge on epidemiology and characteristic pathophysiology of T2DM and CVD (coronary heart disease, heart failure, stroke and peripheral vascular disease) in South Asian migrant population. Specific attention is also drawn to the role of novel risk factors and cultural and socioeconomic factors on occurrence and outcomes of these chronic diseases in this population. Finally the review makes recommendations on various measures including need for further research to tackle this serious health challenge facing the South Asian community.

Introduction

South Asians have origins on the Indian sub-continent (India, Pakistan, Bangladesh, Sri Lanka and Nepal) and collectively they form 20% of the world population. Since the Second World War there has been a progressive migration of people from these countries to many countries in Europe and North America. In UK they are the largest ethnic minority group comprising over 4% of the total UK population [1]. Cardiovascular diseases (CVD) (which include coronary heart disease (CHD) and stroke) are of pandemic status with significant mortality and morbidity and consequent economic impact [2], [3]. However there is significant ethnic variation in its prevalence with South Asians not only on the sub-continent, but also in diaspora harbouring the highest risk of developing these diseases, with a projection illustrating that in 2020 South Asians will contribute 40% of the global CVD burden [4], [5], [6], [7]. Furthermore CVD and type 2 diabetes (T2DM) develop at an earlier age in South Asians and associated complications are seen more commonly compared to white Europeans [6], [7], [8], [9], [10], [11], [12], [13]. The reason for this heightened CVD risk in South Asians is not entirely clear but is thought to be mainly related to high prevalence of insulin resistance and related atherogenic risk factors in this population [6], [14]. It is also likely that factors associated with urban lifestyle/migration such as high calorie diet and lack of physical activity further enhances the underlying insulin resistance and consequent cardiovascular risk. The problem is further made worse by the paucity of evidence based knowledge and guidelines on primary and secondary prevention of CVD specific to this ethnic community [15]. Moreover, factors such as health beliefs, language difficulties, educational level, socioeconomic status and inequalities in access to health care have a further adverse impact on the effective management and outcome of CVD in this population [1]. Not surprisingly, there seems to be a lack of relative decline in CHD and stroke rates in this population compared to Europeans [9], suggesting the inequalities gap is not being as successfully addressed as desired, despite an overall fall in absolute rates in areas such as CHD.

The aim of this article is to review the literature and update the readers on epidemiology, risk factors and pathogenesis of T2DM and CVD in migrant South Asian populations. There have been extensive review articles on CHD and T2DM in South Asian community [16], [17], [18], [19], [20]. However with the recent launch of the NHS Health Checks Programme in England [21], the publication of this updated review is timely and pertinent.

Section snippets

Epidemiology

Currently 246 million people worldwide are affected by diabetes and the number is expected to rise to 380 million by 2025. A substantial 80% increase will be seen in middle to low income countries and the highest rise will be seen in Indian sub-continent [3], [22]. The prevalence of T2DM in the South Asian population living in the UK is around 20% which is nearly fivefold higher than the indigenous White population. Previous studies have also shown that in up to 40% of cases the disease remains

Chronic heart failure

Chronic heart failure (CHF) is a major health problem with a high prevalence and is associated with high mortality and morbidity [103]. People with T2DM are at a significantly high risk of developing heart failure and associated mortality [104]. Possible mechanisms that may explain the underling adverse association of T2DM with CHF include the increased frequency of hypertension and premature CHD and the presence of a distinct diabetic cardiomyopathy possibly resulting from the metabolic

Cerebrovascular disease

Gunarathne et al. in a recent review article have given a detailed account of current evidence related to ischaemic strokes in the South Asian populations [113]. Like CHD, South Asians experience greater burden of stroke and suffer from premature and at least 40% higher stroke related mortality compared to white Europeans [113], [114]. Available information shows that, over the past few decades there has been a tremendous rise in incidence and prevalence of stroke affecting South Asian

Peripheral arterial disease (PAD)

PAD is an important vascular disease with considerable mortality, morbidity and is also associated with increased rates of hospitalisation and reduced quality of life. It is frequently seen in association with other vascular diseases such as CHD, stroke and T2DM. While there is ample information available on PAD in white European populations, much less is known about this disease in South Asian and other ethnic groups. Bennett et al. have recently reviewed the evidence on PAD in different

Raising awareness

Increasing awareness amongst patients as well as healthcare professionals about the heightened risk of CVD and T2DM is of paramount importance. Wider efforts need to be taken at national level with input from healthcare professionals, non-government organisations, diabetes organisations, government authorities and community leaders to tackle this challenge. In UK, the South Asian Health Foundation (SAHF) in collaboration with Diabetes UK and Department of Health is working in this direction.

Conclusions

South Asian populations worldwide have a high prevalence of CVD and T2DM, occurring at an earlier age and being associated with premature and high mortality. Conventional as well as novel risk factors related to central obesity and insulin resistance and the risk factors associated with urban lifestyle are all likely to be contributing in majority of the cases. While more research is awaited in this area, it is reasonable to adopt the current guidelines on primary and secondary prevention of

Conflict of interest statement

Kamlesh Khunti (KK) and Kiran Patel are members of the South Asian Health Foundation. Kamlesh Khunti co-lead the review ‘Diabetes UK and South Asian Health Foundation recommendations on diabetes research priorities for British South Asians’.

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