Screen at 23 – Type 2 Diabetes Risk at Lower BMI for Asians and Asian Americans
By Jeemin Kwon
Why is the BMI cutoff lower for diabetes screening in people of Asian descent? How a new policy could ensure more people with diabetes and prediabetes are diagnosed.
A higher body mass index (“BMI”) is often used as an important risk factor and screening tool for type 2 diabetes.1 (Click here for a BMI calculator, which is a ratio of weight to height.) Historically, a BMI of 25 has been used as the risk cutoff – below 25, risk for diabetes was considered relatively low. In 2015, the American Diabetes Association (ADA) lowered the BMI cutoff to 23 for Asians and Asian American adults. A review of existing research on the link between BMI and diabetes in Asian populations by the Joslin Clinic’s renowned Dr. William C. Hsu was a major driver of ADA’s change.
Recently, states like Massachusetts, California, and Hawaii have passed policies to encourage healthcare providers to "screen at 23," and there is a growing public awareness campaign. It is estimated that over 50% of Asian Americans with diabetes are undiagnosed – screening at 23 could help more people get the care they need. Compared to Caucasians, Asians also have a higher lifetime risk of developing diabetes.
In this case, an Asian or Asian-American person is defined as someone with origins from East Asia (China, Japan, Korea, Mongolia), Southeast Asia (Cambodia, Malaysia, the Philippines, Thailand, Vietnam, Indonesia, Singapore, Laos, etc.), or the Indian subcontinent (India, Pakistan, Bangladesh, Sri Lanka, Nepal, Bhutan).
Why are Asians and Asian Americans at risk for diabetes at a lower BMI than, say, Caucasians? Asians and Asian Americans have a different fat distribution, with more fat typically stored around the waist than on the limbs, a tendency associated with type 2 diabetes. Also, East Asians in particular have a lower ability to produce extra insulin to compensate for initial insulin resistance (read more about insulin resistance here). These differences are probably due to genetic factors, though diet may also take part.
BMI is not a perfect screening tool for diabetes. Since it simply compares weight to height, it doesn’t consider muscle versus fat – e.g., those who are very muscular might have a BMI over 25, but low risk of diabetes. In addition, BMI does not consider where fat tissue is on the body: having a lot of abdominal (belly) fat tissue is a better predictor of diabetes than BMI or even overall body fat – waist to hip ratio is one way to measure this. However, BMI is an easy measurement to determine since it only takes a person’s height and weight to calculate it, so it likely won’t be discarded anytime soon even though it’s far from a perfect measurement.
With this move to screening at 23, some have predicted that thousands who didn’t know they had diabetes will be accurately diagnosed as a result. By sharing this information with friends and family, as well as your healthcare provider, you can help others receive the health support they need!
1. The units for BMI are kg/m2.