Why are South Asians at higher risk of Type 2 diabetes, despite being less obese than Caucasians? Sangeeta Pradhan RD, CDE explains

Type 2 diabetes is one of the fastest growing diseases globally due to unfavourable changes in modifiable risk factors and a high genetic susceptibility in certain populations. With obesity growing at sky rocketing rates worldwide, the metabolic disorders that go hand in hand with it are also rising proportionately. Asia is at the epicentre of this diabetes epidemic. 60% of the world’s diabetic population are from this part of the world. Asian Americans are one of the fastest growing ethnic groups in the United States, with their numbers projected to double by the year 2060.

While most ethnic communities are affected, South Asians both in their native countries and abroad are disproportionately affected. This makes it imperative to take a hard look at the contributing factors and explore meaningful interventions.

“The paradox is alarming – Asians have twice the prevalence rates of diabetes despite lower rates of obesity compared to Caucasians!”

Type 2 diabetes occurs at a younger age, at a higher rate and at a lower Body Mass Index (BMI) amongst Asian and South Asians as compared to whites. This was demonstrated in a population-based, multi-ethnic cohort study conducted in Ontario, Canada, which compared incidence rates of diabetes across white, South Asian, black and Chinese individuals aged greater than or equal to 30 years, who were followed up for 12.8 years for diabetes incidence. What was striking about this study was that after adjusting for age, sex, BMI and socio-demographic characteristics, it showed that South Asians were 3.4 times more likely, blacks were 1.99 times more likely and Chinese subjects were 1.87 times more likely to develop diabetes compared to white subjects.

On an average, diabetes occurred 9 years earlier in South Asians, 3 years earlier in Chinese and a year earlier in blacks compared to whites

Moreover, while diabetes was diagnosed at a BMI of 30 in whites, it was diagnosed at a BMI of 24 in South Asians, 25 in Chinese and 26 in blacks. This study clearly demonstrated that while the definition of obesity using a BMI of 30 has been well validated in whites, it is not a reliable measure in non–white populations, and underscores the need for ethnic specific BMI cut-offs in these populations.

So what creates this disparity?

Asians have the dubious distinction of having more belly fat and less muscle mass compared to Caucasians at comparable BMIs. Emerging evidence shows that visceral fat is a significant risk factor for impaired glucose tolerance* amongst Japanese Americans. At any given BMI, South Asians have higher body fat, visceral or abdominal fat, waist circumference and lower skeletal muscle mass, which translates to increased insulin resistance**, metabolic syndrome, and increased heart disease risk as compared to Caucasians. This appears to be a defining characteristic of the Asian population – the so-called “Asian Indian phenotype” which is also referred to as “normal weight, metabolically obese phenotype”.

What do epigenetics have to do with this?

Epigenetic changes*** in gene expression that occur due to secondary to malnutrition related stressors in the intra-uterine environment can lead to the deposition of central fat as an adaptive response in infants that are exposed to nutrient scarcity because of maternal under-nutrition. Despite having lower birth weight, South Asian babies have more central obesity as compared to their Caucasian counterparts. Thus, fetal programming in the uterus can lead to fat preservation, which can become maladaptive later in life when these insulin resistant babies are exposed to calorie dense foods as adults – increasing their risk of Type 2 diabetes. This phenomenon is explained by the “thrifty phenotype hypothesis,” which postulates a mismatch between the uterine environment (nutrient scarcity) and adulthood (calorie abundance). This often occurs due to rapid urbanization and nutrient transitions in developing countries, as a result of rapid economic development and its associated socio-economic issues. This may also be seen when folks who faced food scarcity in their early childhood in native developing nations, migrate to more affluent countries of the West where food is more abundant. Thus, an inherent genetic susceptibility along with unfavourable changes in lifestyle factors brought on with migration to the West may set the stage for increased insulin resistance and subsequent diabetes.

So how does diet play a role?

Rapid urbanization and industrialization in Asia has fuelled a concomitant shift in nutrient patterns. The traditional diets of Asia, high in coarse, unprocessed grains are being replaced with polished white rice and refined wheat, not to mention the consumption of fast and convenience foods as the population transitions from an agriculture based to a faster paced, service based, global economy. On the same token, acculturation in the West (think “diet transplantation”), has been instrumental in migrant Asian populations adapting to Western diets that are calorie dense, higher in animal protein and high in refined grains and sugar. A recent meta-analysis showed that a 2-serving per day increase in whole grain intake was associated with a 21% lower risk of Type 2 diabetes.

“The Nurses’ Health Study showed that intake of white rice is associated with increased risk of diabetes, while brown rice has a protective effect

The adverse effects of high glycaemic load diets are more prevalent in overweight people secondary to insulin resistance. Prior to rapid urbanization throughout Asia, the detrimental effects of such diets were offset by increased physical activity as most of the population was engaged in hard, physical labour and sedentary lifestyles were less common. That is not the case now in most cases!

BMI disparities:

BMI cut-offs have had to change given the discrepancies in BMI between Asian and European populations, underscoring the fact that traditional methods for assessing metabolic disease risk may not be applicable to the Asian population. We just cannot use the same yard stick any more for assessing disease risk as we would miss the bulk of the folks at risk in Asian populations. To this end, the American Diabetes Association recently lowered its screening criteria for diabetes for Asians to 23 as opposed to 25 used in Caucasians. Thus, testing for diabetes should be considered for all adults who present with a BMI of ≥23 kg/m2.

So what does this mean for you?

If you are of Asian descent, you might want to start with determining what your BMI is by clicking on this link from the Joslin Diabetes Centre. For example, let’s assume you are an Asian male who is 5’10” and weighs 172 lbs., with a BMI of 24.7. While you would be considered of normal weight by Caucasian standards based upon BMI, you would be at a higher risk by Asian standards given lower screening criteria and should get tested for diabetes.

South Asian titbits:  How do you reduce your risk?

Know thy numbers: For starters as noted above, know what your BMI is, as well as waist circumference. (Click on this link from Joslin to find out.)

Small changes, big results: Just a modest 5-10% weight loss targeting the waist line can make a significant difference in lowering your risk for pre-diabetes/diabetes or preventing its progression if you already have either condition.

Make fibre your friend: Fibre slows down digestion, thus reducing blood glucose or sugar spikes seen with refined foods that are low in fibre. Aim for approximately 25 -30 grams of fibre per day if you are a woman or 30-38 grams per day if you are a man. Be sure to increase your water intake as you increase your fibre intake.

Wholesome whole grains: Replace refined grains (foods made with white flour or maida), and white rice with whole grains such as quinoa or farro. Make high fibre rotis by mixing 2/3 cups of whole wheat flour with 1/3 cup of high fibre ragi (millet flour) to make a very high fibre roti. Don’t forget to pair with a source of protein such as channa (chickpeas) or rajma (kidney beans), and some veggies sautéed in olive oil to create a complete and satisfying meal. Make upama with bulghur or dalia, instead of refined rava or try a whole moong dal cheela (pancake) for breakfast.

Love the lentils: Toss a ½ cup of whole, cooked moong, masoor, preferably in a sprouted form into that salad at lunch or toss with fresh salsa, tamarind chutney and/or your favourite choice of chutney to make a quick “chaat”. Simple, healthy and delicious to boot!

Fill up with fruit: 1 cup of blackberries can give you a hefty 8 grams of fibre and a pear provides as much as 6 grams, so dig in and enjoy!

Load up on veggies: Veggies are practically calorie free, high in fibre and nutrient dense. Fill your plate with vegetables for an additional burst of antioxidants and fibre. For more delicious tips, check out my article on Whole grains and fibre: Unravelling the puzzle!

Power up with probiotics: Round out your meals with a cup of yogurt or buttermilk with live and active cultures to harness the power of beneficial bacteria. Emerging evidence shows that your gut bacteria can influence a host of functions, ranging the gamut from the digestion and absorption of nutrients to regulating the immune response, the inflammatory tone in your body, and indeed modulating the course of chronic disease itself.

Dump added sugars and excess fat, especially undesirable fats: Avoid fried foods and foods with added sugars including sugar sweetened beverages such as sodas which may have as many as 10 teaspoons of sugar in a 12 oz can. Excess sugar has been associated with increased oxidative stress and chronic inflammation. Emphasize whole plant fats from nuts, seeds, avocados, or fatty fish.

Get moving: Experts recommend 150 minutes of aerobic activity per week, but if you have been sedentary all your life, even 5-10 minute short spurts of activity such as a walk around the block or up to the corner store and back may be enough to get you started.

Seek the advice of an expert: Please consult a Registered Dietitian or Certified Diabetes Educator for specific guidelines, including portion sizes tailored to your unique needs. These professionals are trained to discuss with you the prevention of acute and chronic complications from diabetes and will work with you on home blood glucose monitoring and customizing your meal plan to achieve the desired results.

Take home the message: Remember diabetes is a consequence of modifiable risk factors such as weight, diet, and activity in folks who are at risk. A modest 5-7% weight loss targeting the waistline may be adequate to overcome insulin resistance. Take small steps today to achieve dramatic results tomorrow, starting with getting screened for diabetes.

“Spread the word. Here’s to your health!”

Written by Sangeeta Pradhan, RD, CDE. She is a Registered Dietitian, Certified Diabetes Educator, professional speaker, guest blogger for Food and Nutrition magazine, USA, Nutrition Columnist for Indian New England news, recipe developer, and practices at a Physician’s practice group in Boston, MA, USA.

This article was originally published by her in “The Asian Paradox: What puts Asians and South Asians at a higher risk for Type 2 diabetes!

 

Disclaimer: All the content on this blog is strictly for informational purposes only, and should not be construed as medical advice. Please consult your doctor or registered dietitian for recommendations tailored to your unique needs.

*Impaired glucose tolerance: Blood sugar is above normal, but not high enough to fall in the “diabetic range”.

**Insulin resistance: A condition when the cells in your body do not respond to signals received from the hormone insulin as it tries to move sugar (fuel) from your blood to your cells. This leads to increased blood sugar levels and may act as a precursor to full-blown diabetes.

***Epigenetic changes: Changes in DNA, often related to environmental influences that can switch genes on and off, without changing the DNA sequence itself.

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One comment

  1. Thank you, Sourajit!I would urge every one who visits this site to spread the word to their South Asian neighbours and friends. It is imperative that we recognize the need for aggressive screening and timely interventions. We can turn the course of this epidemic if we do so. Diabetes is preventable!

    Liked by 1 person

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