The blanket term “South Asian” encompasses people who originate from India, Pakistan, Sri Lanka, Bangladesh, Bhutan, Nepal and Maldives. It’s a known fact that being South Asian is an independent risk factor for the development of type 2 diabetes (DM2).¹ South Asians comprise close to 25% of the world’s population. They represent one of the largest immigrant populations in Canada.² With the rising prevalence of DM2, (new projections indicate that by 2012, about 2.8 million individuals across Canada will be living with diabetes, an overall increase of about 25% from 2007)³ it’s essential to focus on at-risk populations to reduce the complications and the mounting burden on our healthcare system.

Reasons for ethnic disparity

Why is this group more vulnerable? Genetic susceptibility and central visceral body fat distribution are thought to play a role, along with environmental influences such as sedentary lifestyle, dietary choices and acclimatization to culture and stress.⁴

Genetics

Various studies have postulated a genetic basis for susceptibility in this cohort including intrauterine, fetal and developmental origins. Studies on cord blood of newborn Indian babies have shown the hyperinsulinemic and insulin-resistant phenotype of Indians to be present from birth.⁵ In addition to this, the “thrifty-gene hypothesis” proposed 10 years ago put forward the concept that environmental factors acting in early life, in particular undernutrition, may influence the development of type 2 diabetes later in life.⁶ Indian babies are known to be amongst the smallest in the world⁷ but have been described as having the “thin-fat” phenotype in utero — smaller body organs and lower muscle mass but relatively preserved body fat. This body composition has been suggested to persist post-natally, predisposing South Asians to an insulin-resistant state later in life.⁸

Fat and the metabolic syndrome

Consistent with the thin-fat phenotype theory, anthropometric studies have shown Indian babies to have a higher body fat percentage when compared to their Western Caucasian counterparts, a surprising finding given their overall smaller size. This translates into adulthood with research suggesting that adult Indians have more visceral body fat and lower muscle volumes than white Caucasians, African Americans and other ethnic groups of comparable body mass index (BMI).⁹ Many South Asians are considered “thin” by conventional criteria — a low BMI, but have a higher association with the metabolic syndrome and its constituents including central obesity (also known as apple obesity), insulin resistance, hypertension and atherogenic lipid abnormalities.¹⁰ A seemingly healthy BMI in this cohort can be misleading, as South Asians suffer from the deleterious complications of the metabolic syndrome at considerably lower BMIs than the standard WHO cut-off points for overweight.^11,12 Abdominal obesity is a characteristic feature of South Asian populations and carries a known association with insulin resistance.¹³ There are now WHO-recognized specific ethnic cut-offs for South Asians BMI and waist circumference (WC) for overweight and obesity.

Diet, stress and culture

The South Asian diet is traditionally rich in fat and carbohydrates, with rice being a staple and clarified butter (ghee), being commonly used as a cooking oil and garnish. In addition, desserts rich in fats and sugar are part of almost all religious and cultural events.¹⁴ Sedentary lifestyles are likely in part due to urbanization, which has been shown to reduce physical activity, increase BMI and upper body adiposity. It’s been found that new immigrants and those in a low socio-economic bracket have a 3-fold increased risk of developing DM2, compared to their Caucasian counterparts.

Barriers to treatment

Lack of awareness, compliance issues, and cultural attitudes are among the various hurdles faced by healthcare practitioners. Studies have shown lower awareness among South Asians of diabetes and about the nutritional content of their diet, when compared to Caucasians.^15,16 The importance of offering and accepting food in the strong hospitality culture of South Asians has also been recognized, and some South Asians see their traditional diet as a specific barrier.¹⁷ Anecdotal opinions of family physicians practicing in ethnically dense regions in Canada have found that South Asian patients are often reluctant to purchase medications and diabetes supplies because of cost.¹⁴ The importance of self-monitoring blood glucose is also not well recognized. Often, denial about disease plays a large role in seeking or avoiding treatment. Many patients obtain medications from their countries of origin without regular follow-up or direction, which can be both unsafe for patients and challenging for healthcare practitioners. Despite South Asians’ high regard for education, this cohort has demonstrated poor levels of knowledge about their disease and limited motivation to attend educational sessions.¹⁸ Additionally, many individuals are unaware of community-based culturally specific resources that are available.

Conclusions

South Asians are a population vulnerable to the development of dysglycemia, DM2, and the metabolic syndrome. With the growing number of people affected, recognizing high-risk individuals is vital to prevent adverse outcomes. Specific South Asian parameters for BMI and WC should be used to determine risk of comorbidities. Despite the growing epidemic, there is hope; education combined with achievable lifestyle goals may be starting points for promoting weight loss and healthy behaviours. A 2-3% reduction in energy intake or an extra 10-15 minutes of walking has been shown to offset weight gain in over 90% of the population in certain Asian countries. Culturally insightful approaches with regard to diet-specific recommendations, patient-specific barriers and self-empowerment through education may be beneficial in this population.

For patients

1. Government resources: www.health.gov.on.ca/en/ms/diabetes/en/vid_southasian.html
2. Canadian Diabetes Association: South Asian Chapter: www.diabetes.ca/files/south-asian-faqs.pdf
3. South Asian Diabetes Chapter: southasiandiabeteschapter@gmail.com 416-363-0177 x 7408.

Resources

1. Public Health Agency of Canada. Available at: www.phac-aspc.gc.ca/cd-mc/diabetes-diabete/risk_factors-facteurs_de_risque-eng.php
2. Statistics Canada. Available at: www40.statcan.gc.ca/101/cst01/demo34b-eng.htm
3. Public Health Agency of Canada, Diabetes in Canada, 2009. www.phac-aspc.gc.ca/publicat/2009/ndssdic-snsd dac-09/1-eng.php
4. Creatore MI. CMAJ; 182(8):781-89.
5. Yajnik CS. J Clin Endocrinol Metab 2002;87(12):5575.
6. Hales CN, Barker DJ. Diabetologia 1992;35:595-601.
7. Yajnik CS. J Nutr 2004;134(1):205-10.
8. Yajnik CS. Int J Obesity 2003;27:173-80.
9. Elliott T, Viberti G. Baillière’s Clinical Endocrinology and Metabolism 1993; 7(4):1079-1103.
10. Canadian Diabetes Association: The Metabolic Syndrome. www.diabetes.ca/diabetes-and-you/what/meta bolic-syndrome/
11. WHO Expert Consultation. Lancet 2004; 363(9412):902.
12. Pub Med Health. The Metabolic Syndrome: www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004546/
13. Ramachandran et al. Lancet 2010;375 (9012):408-18.
14. Sohal P. Can J Diabetes 2008;32(3):206-10.
15. Pardan S. and Mahomed I. Eye 2004;18:509-13.
16. Rankin J. Public Health 2001;115(4):253-60.
17. Samanta A. et al. Hum Nutr Appl Nutr 1987;41(3): 160-3.
18. Stone, M. Public Health 2001;115(4): 253-60.