Why Asians develop diabetes at lower ages and BMIs
Published on
26 Oct 2021
Published by
The Straits Times
SINGAPORE - According to the International Diabetes Federation, more than half of the people with diabetes in the world are from Asia, which also has the highest mortality rate from the disease despite advances in treatment.
Asians are at higher risk of developing diabetes and are also seeing earlier disease onset. One in two adults with diabetes in Asia remains undiagnosed and are at increased risk of developing serious and costly complications.
Singapore is a microcosm of Asia with its three main ethnic groups - Chinese, Malays and Indians - representing three major Asian populations: East Asians, South-east Asians and South Asians respectively.
According to the Ministry of Health, one in three Singaporeans has a lifetime risk of developing diabetes. That is one million people by 2050. This projected rise in diabetes prevalence is thought to be driven by Singapore's rapidly ageing population and the expansion of people's waistlines.
Why are Asians more susceptible to diabetes?
The Asian Indian Prediabetes study is a diabetes prevention research study on Indians conducted in Singapore. During screening, the youngest person found to have prediabetes - or blood glucose levels higher than normal, but lower than the diabetes range - was 26 years old. Individuals with a body mass index (BMI) of 25 to 26, which is in the overweight but not obese range, were found to have prediabetes.
These findings are consistent with the Diabetes Study of Northern California (Distance), a multi-ethnic study of more than two million people in the United States that showed Asians were diagnosed with diabetes at BMIs below the threshold for obesity, compared with other ethnic groups.
Another study, which compared data from 29,369 individuals in population studies conducted in Asia and Europe after 1980, showed that the prevalence of diabetes started to increase by age 30 in Asians, compared with age 45 in Europeans.
Why do Asians develop diabetes at younger ages and lower BMIs than others? Can this be attributed solely to rising obesity rates? But aren't obesity rates higher in the Americas, Europe and Australia?
While the importance of good nutrition and regular physical activity for optimal health is well acknowledged, many studies have revealed profound differences in disease risk among individuals, and biological responses to different dietary exposures and exercise methods.
Asians show a significantly higher blood glucose and insulin response than Caucasians after consuming 75g of white bread carbohydrate in a study. This study was conducted in lean, young individuals yet some of these apparently healthy Asian volunteers had post-meal responses that would have met the criteria for prediabetes.
Similar trends have been observed in the Asian Indian Prediabetes study, in which nearly two-thirds of the 32 participants in the first two cohorts had normal fasting blood glucose levels, but elevated two-hour oral glucose tolerance test readings in the prediabetes range.
These findings, corroborated by other studies, imply that such abnormalities may be one of the earliest signs of metabolic dysfunction preceding the development of diabetes in Asians, and can occur in the absence of obesity or advanced age.
Still, there are differences among Asian ethnic groups. Compared with Chinese and Malays, Indians have lower insulin sensitivity (a measure of how responsive the body is to the effects of insulin) and exhibit significantly higher glycaemic and insulin responses to both high and low glycaemic index (GI) foods.
GI is a rating system for carbohydrate foods, which reflects how quickly each food affects a person's blood glucose level when that food is eaten on its own.
Reductions in insulin sensitivity typically trigger increased insulin production to maintain normal blood glucose levels.
Reduced insulin sensitivity has been observed in Indians early in life, in which high insulin levels have been detected in cord blood and during adolescence.
While obesity does predispose individuals to diabetes, studies show that the effect of obesity on reducing insulin sensitivity appears to be stronger in Chinese and Malays than Indians.
There is growing evidence that reduced beta-cell function may be an early driver in diabetes in Asians, playing a more critical role than insulin sensitivity. Beta cells, found in the pancreas, synthesise and secrete the hormones insulin and amylin.
Inadequate beta-cell insulin secretion in response to decreased insulin sensitivity has been observed in Malays, while in Indians, beta-cell exhaustion occurs at a younger age and the function of these cells declines more rapidly than in people of other ethnicities.
These findings suggest that although existing public health efforts to prevent or treat obesity are important in reducing diabetes, it may be more effective to implement strategies that target the specific metabolic abnormalities that predispose Asians to developing the disease.
For example, strategies to preserve beta-cell function, slow beta-cell decline or compensate for an inadequate beta-cell response by reducing the need for insulin may be particularly advantageous for prevention and control of diabetes in Asians.
This is an area of interest to pharmaceutical companies, although emerging evidence indicates that diet and lifestyle strategies offer remarkable potential.
Given how early in life these metabolic abnormalities can develop in Asians, it is advisable to initiate these targeted diet and lifestyle interventions earlier in adulthood, and even from the preconception and prenatal period.
Such strategies necessitate moving from a one-size-fits-all to a more nuanced approach to dietary advice.
The Asian Indian Prediabetes study is underpinned by the concept of precision nutrition, with a tailored diet and lifestyle strategy to prevent diabetes in Indians.
These strategies can complement public health recommendations aimed at improving access to healthy food options and healthcare for vulnerable individuals.
While Singapore has fought the "war on diabetes" on many fronts, it is important that the country sharpens its arsenal by implementing more targeted diet and lifestyle solutions.
• Jeannie Tay is a postdoctoral research fellow passionate about nutrition and exercise, and the causes and prevention of diabetes and obesity.
Source: The Straits Times © Singapore Press Holdings Limited. Reproduced with permission.
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