A larger proportion of Blacks, South Asians and Chinese people live with prediabetes and undiagnosed type 2 diabetes in the United Kingdom compared with Caucasians, a new study has found. 

Notably, 16.8% of Blacks, 14.8% of South Asians and 8.9% of Chinese adults live with prediabetes or undiagnosed type 2 diabetes compared with only 4.0% of Caucasians.

The study, “Ethnic differences in prevalence of actionable HbA1c levels in UK Biobank: implications for screening,” was published in BMJ Open Diabetes Research and Care. 

Type 2 diabetes rates are increasing rapidly worldwide, especially in low-income and middle-income countries. According to the International Diabetes Federation (IDF), 285 million people lived with diabetes in 2009. Today, an astonishing 463 million adults live with diabetes, and that’s estimated to rise to 578 million by 2030 and 700 million by 2045. 

While people with prediabetes have a high risk of progressing to type 2 diabetes and developing cardiovascular disease (CVD), adequate lifestyle changes can prevent progression and lower CVD risk if detected early.

However, the scale of prediabetes and undiagnosed diabetes and the best way to identify people with these conditions are unclear.

Now, a team of scientists investigated the rates of prediabetes and undiagnosed diabetes by ethnic group in the UK and the average number of people who would need to undergo testing to identify each case. 

The study used data from the UK Biobank, a large population cohort of adults aged 40–69 years recruited across the UK between March 2006 and December 2010. All participants self-identified as white, Indian, Pakistani, Bangladeshi, Black African, Black Caribbean or Chinese. Participants provided detailed demographic, lifestyle and medical history information, biological samples, weight, and height measurements. Their plasma glycated haemoglobin (HbA1c) levels were also calculated. 

A total of 433,856 adults were included in the study. Overall, the cohort consisted of 96.7% white, 1.7% South Asian, 1.3% Black and 0.3% Chinese adults. White participants were older, Black participants were more likely to live in deprived areas, and Black women had the highest body mass index (BMI)

The overall prevalence of prediabetes was 3.6% and 0.8% for undiagnosed diabetes. However, the rates varied between ethnic groups. 

The rate of prediabetes was 3.3% among white participants compared with 13.8% among Blacks, 11.0% among South Asians and 7.8% among Chinese. Similarly, the rate of undiagnosed type 2 diabetes was lowest in Whites and higher among other ethnicities: 0.7% in whites, 3.6% in South Asian, 3.0% in Black and 1.1% in Chinese adults. Furthermore, prediabetes or undiagnosed diabetes rates were higher in white and South Asian men compared to women and increased with increasing age. 

The researchers determined that 25 white adults would need to be tested to identify one case of either prediabetes or undiagnosed diabetes compared with only 6 Black or 7 South Asian adults. 

“Our findings suggest that 4.7% of individuals aged 40-70 years old in the UK have actionable HbA1c concentrations. More importantly, 1 in 6–7 individuals of black or South Asian ethnicity have actionable values, and approximately 1 in 30 are living with undiagnosed diabetes,” the researchers wrote. 

“The risk of having prediabetes or undiagnosed diabetes is magnified by older age, male sex, living in deprived areas, and having unhealthy lifestyles,” they added. 

Many diabetes prevention programmes have been set up to lower diabetes rates by identifying high-risk populations early and preventing those with prediabetes from progressing to type 2 diabetes or its related complications. 

Oral glucose tolerance tests and HbA1c tests are the two tests commonly used to identify people with high blood glucose levels. Although more expensive, HbA1c is easier to administer and can be done at any time of the day. 

“Higher HbA1c levels are more accepted in predicting incident cardiovascular disease and microvascular damage, at least as well as other glycaemia measures. As HbA1c can be done any time of the day, irrespective of fasting status, it is a more feasible test for widespread community-based adoption,” the researchers wrote. 

Screening for diabetes is essential because it increases the chances of diabetes remission and reduces the risk of progression to complications, especially in younger, non-white adults who lose more life than older adults from the condition. 

In conclusion, “HbA1c is extremely efficient at identifying prediabetes and undiagnosed diabetes in middle-aged and old-aged South Asian and black individuals. Therefore, consideration should be given to single-stage mass screening of these high-risk populations using HbA1c.”