Dr Aravinda Jagadeesha MD, MRCP(London,UK), FRCP(Edinburgh,UK), Consultant Diabetologist, Dr Aravind’s Diabetes Centre, Karnataka, India

Diabetes mellitus (DM), an increasingly common metabolic disorder, creates a significant public health burden.  The World Health Organization (WHO) has identified that non-communicable diseases (NCD) are an important global health hazard and DM is one of the four main NCD which immediately demands the global attention.1 This chronic disorder is also a top 10 cause of death globally and has attained pandemic proportions worldwide. In 2015 diabetes killed around 1.6 million people globally (direct cause of death).2 According to the recent Global Burden of Disease Study (2015), diabetes ranked 15th in the global list of leading causes of years of life lost (YLLs).3 Furthermore, the third highest risk factor for global premature mortality is high blood glucose after high blood pressure and tobacco use.4

EPIDEMIOLOGY

According to the estimates of the International Diabetes Federation (IDF), globally 415 million people are suffering from diabetes (with global prevalence: 8.8%) of which 75% live in low- and middle-income countries. With this trend, by 2040, the world will have 642 million people suffering from diabetes. Type-II DM is the predominant clinical form rather than type-I DM. The majority of the diabetes population (87-91%) in high- income countries have type-II diabetes. Data for relative proportions of type-I and type-II diabetes is not available for low- and middle- income countries,. Globally the type-I diabetes population increases each year by approximately 3 %.4

 

INDIAN SCENARIO

India is an influential hub for the global diabetes epidemic with the second highest diabetes population in the world (~69 million as of 2015). With this trend, India would be home to 123.5 million people with diabetes by 2040. Globally, the second largest number of children (<15 years) with type-I diabetes also resides in India (70,200) after the USA (84,100). 4


Due to the enormous size, diversity and heterogeneous nature of India’s geography, large differences exist in the prevalence of diabetes between Indian states. Furthermore, region-specific studies performed at different times using different sampling designs do not accurately reflect or capture the country-specific disease burden as a whole.7 The ongoing national Indian Council of Medical Research–INdia DIABetes study aims to estimate the national prevalence of diabetes and prediabetes and is the largest nationally representative study.  Anjana et al7 from the ICMR–INDIAB Collaborative Study Group recently published cumulative data from 15 states (with total adult population of 363·7 million people; 51% of India’s adult population). Anjana et al estimated the prevalence of diabetes in India to be 7·3% and the prevalence of prediabetes to be 10·3% (WHO criteria) or 24·7% (American Diabetes Association (ADA) criteria) depending on which definition was used. However, these prevalence figures are based on data from 15 out of 31 states and thus can’t be considered as final, since the bigger states are yet to be sampled including the National Capital Territory of Delhi, Kerala, Uttar Pradesh and Goa. Anjana et al estimated that prevalence figures varied across different states with Bihar showing 4·3% prevalence and Punjab with 11·2% prevalence in urban and 5.2 % in rural areas. Higher prevalence of diabetes is also reported from states with greater per capita GDP e.g. Chandigarh (GDP of US$ 3433) had the highest prevalence of 13·6%). Furthermore, in rural areas, prevalence of diabetes was higher in states with individuals of high socioeconomic status.This disturbing trend indicates that the epidemic of diabetes in India is spreading to those individuals who can at least afford to pay for its management.

Associated risk factors and possible aetiology for rising trend in India:

The interplay of multiple factors plays an important role in predisposition of Indians to diabetes such as genetic traits, environmental factors, and obesity associated with lifestyle changes, rising living standards and steady urban migration. There are limited regional studies conducted to understand the prevalence.

The heterogeneity of the population in India with respect to culture, ethnicity and socio-economic conditions may lead to potential error in direct extrapolation of regional results. Limitations of existing studies of diabetes prevalence in India are ad hoc surveys, lack of uniform methodology, small sample sizes, inadequate rural representation, incomplete diagnostic work etc.

The Indian Council of Medical Research (ICMR) conducted a large community study that revealed that the population proportion affected in states of Northern India (Chandigarh 0.12 million, Jharkhand 0.96 million) is lower compared to Maharashtra (9.2 million) and Tamil Nadu (4.8 million).8 The National Urban Survey reported a similar trend: 11.7 % in Kolkata (Eastern India), 9 11.6% in New Delhi (Northern India), and 9.3 % in Mumbai compared with 13.5 % in Chennai, 16.6 % in Hyderabad, and 12.4 % Bangalore (South India). 10 It was observed that there is patterns of diabetes incidence related to the geographical distribution of diabetes in India.

North Indians are migrant Asian populations and south Indians are the host populations. 11 This is suggested as an explanation for the difference in this regional distribution. This cause-and-effect needs to be demonstrated through further research. Cultural and ethnic differences needs to be studied in further detail to understand the differences in diabetes etiology between Indian and other ethnic groups within India.

Access to reliable screening methods and anti-diabetic-medication might contribute to differences in diabetes prevalence between rural and urban population. Disproportionate allocation of health resources and poverty in rural areas is considered as an add-on to prevailing adverse conditions showing variation in trend.  Shortfalls like inadequate infrastructure, lack of available counselling and poor diabetes screening and preventive services require to be urgently addressed for observed rural-urban inequality in diabetes intervention.

Obesity is one of the major risk factors for diabetes, yet there has been little research focusing on this risk factor across India. 12 The relationship between high body mass index BMI and diabetes is elusive. Obesity is considered as a risk factor for diabetes, however there is higher prevalence of diabetes in the Indian population with lower overweight and obesity rates compared to western countries suggesting that diabetes may occur at a much lower BMI compared with Europeans. 

One international study reported that worse diabetes control in individuals is associated with   longer duration of the disease (9.9±5.5 years), 13 resulting in higher rate complications like neuropathy (24.6 per cent), cardiovascular complications (23.6 %), renal issues (21.1 %), retinopathy (16.6 %) and foot ulcers (5.5 %). Ineffective glycaemic control responsible for micro- and macrovascular changes can predispose these patients to other complications such as diabetic myonecrosis 14 and muscle infarction.15

Commonly associated infections like Plasmodium falciparum in developing countries like sub-Saharan African countries have been noted rise in patients with diabetes mellitus16.Both conditions together result in various complications that increase morbidity and limit treatment options in already resource-deprived countries. Unavailability of investigations in a large section of the population 16, “clinical inertia” for initiating insulin therapy associated with complexities of the insulin regimen and lack of clarity and inadequacy in Indian guidelines are also responsible for wide disparity in treatment preferences across the country.17

In the near future DM is trending towards a potential epidemic in India.  The level of morbidity and mortality due to diabetes and its potential complications are enormous, and pose significant healthcare burdens on both families and society.  Diabetes is now being shown to be associated with a spectrum of complications.

Further research in geographical, socio-economic, and ethnic variations in India can provide valuable insights which will help better understanding of the prevalence of diabetes.

REFERENCES

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