Adult early onset type 2 diabetes disproportionately affects South Asian and African-Caribbean individuals, who have an earlier age of onset and, in the case of South Asian people, an accelerated development of the disease compared with White people, indicates a UK primary care data analysis.
The research was presented at the European Association for the Study of Diabetes (EASD) Virtual Meeting 2020 on September 24, which was held online due to the COVID-19 pandemic.
BMI ‘Dose Effect’
A team from Imperial College London examined data on more than 1.4 million primary care patients, finding that, compared with White people, the prevalence of early onset type 2 diabetes (defined as at age 18-44) was more than twice as high in African-Caribbean individuals, and over three times higher in South Asian people.
The results also showed that there was a “dose effect” of body mass index (BMI), with younger onset associated with an increased rate of overweight and obesity, and that the incidence of early onset type 2 diabetes rose much faster in South Asian individuals than their White counterparts.
Study author Janthula Ranchagoda, a fifth year medical student in the Department of Medicine, Imperial College London, said that, with the increasing incidence of early onset type 2 diabetes: “The burden this group is going to pose in the coming years is only going to rise.
“The other key point is that data from cardiovascular outcome trials in this group is severely lacking, because people with type 2 diabetes under the age of 40 are severely underrepresented in large clinical outcomes studies.”
Mr Ranchagoda added that, consequently, “our knowledge base to provide targeted treatments to this group is inhibited”.
The results also have “relevance to the current pandemic”, he said. “We know from studies that people with obesity and those from ethnic minority groups are particularly at risk from COVID-19 and there is some reflection to be had whether or not this early onset type 2 diabetes group in adults has an additional risk from the SARS-CoV-2 pandemic.”
Dr Shivani Misra, Department of Medicine, Imperial College London, who led the study, said that the “elephant in the room for any researcher working on early onset type 2 diabetes” is how to tackle the increasing incidence.
She told Medscape Medical News: “I think no single approach is going to be sufficient to deal with this huge, rising problem.
“Obviously there are some great public heath initiatives coming out of NHS England at the moment, both the diabetes prevention programme and also the type 2 diabetes remission programme.”
However, Dr Misra said that the “evidence base that those programmes work in people with early onset type 2 diabetes is lacking, and there’s some emerging evidence that those programmes will need to be tweaked for specific ethnic minority groups”.
Another issue is that many of the individuals with early onset type 2 diabetes have been hard to reach in terms of prevention and management campaigns.
“There’s often very strong family histories of type 2 diabetes amongst Asian and Afro-Caribbean young people and there’s almost a desensitisation to how severe this condition is,” Dr Misra said.
“So I think we need to really reach out to these communities, at the grass roots level, and try to take everyone on the journey with us so they understand the seriousness of this condition.”
Presenting the study, Mr Ranchagoda said that, while there have been increasing reports of paediatric diabetes, there has also been a rapid increase in the incidence of type 2 diabetes in young adults, defined here as an onset between 18 and 44 years of age.
He underlined that these patients are “important to study”, because “we know they have a higher complication risk” compared with those diagnosed at an older age. “We’ve seen from previous studies that they have a higher frequency of cardiovascular complications,” as well as an increase in the number of life years lost.
To investigate the ethnic distribution of adults with early onset type 2 diabetes, as well as the relationship between BMI and age at diagnosis, the researchers gathered primary care records on 2,398,603 individuals living in North West London.
Of those, 135,654 had been coded as having type 2 diabetes, among whom 93,584 were coded as being of White, South Asian or African-Caribbean ethnicity.
Within this group, 33,666 had been diagnosed with type 2 diabetes up to 5 years previously, and 7672 were classified as having early onset type 2 diabetes.
The team found that the overall prevalence of type 2 diabetes was higher in non-White ethnicities, at 10.1% among South Asian individuals and 8.3% among African-Caribbean people, compared with 3.4% of White individuals.
The age distribution of type 2 diabetes varied significantly between ethnicities, with 30.6% and 25.8% of South Asian and African-Caribbean patients, respectively, diagnosed at 18–44 years of age, versus 15.7% of White patients (p<0.001 for trend).
Moreover, the development of early onset type 2 diabetes appeared to be “accelerated” in South Asian people, with the distribution curves separating almost as soon as the incidence began to climb around 20-years of age.
Median BMI was, however, significantly lower for non-White individuals with early onset type 2 diabetes, at 29.3 kg/m2 for South Asians and 32.3 kg/m2 for African-Caribbean individuals, versus 34.3 kg/m2 for White people (p<0.001 for trend).
This was reflected in a higher proportion of White individuals with early onset type 2 diabetes who were overweight or obese, at 92.2% versus 82.9% for South Asians and 87.5% for African-Caribbean individuals.
In all three groups, there appeared to be a dose effect of higher BMI being associated with an earlier onset of type 2 diabetes.
Across the three ethnic groups, 82.9% of patients diagnosed between 18 and 44 years of age were overweight or obese compared with 75.3% of those diagnosed between 55 years and 79 years.
This effect was also seen in South Asian people when using ethnicity-adjusted BMI categories, with 93.5% diagnosed with type 2 diabetes between 18 and 44 years of age overweight and obese compared with 89.4% of those diagnosed between 55 and 79 years of age.
In the post-presentation discussion, Mr Ranchagoda said the study is limited by the inability to test for genetic variants related to type 2 diabetes, due to relying on GP-coded, population level data.
He also said that it was not possible to obtain measures of waist circumference, “which ideally we would have liked to have but unfortunately when you collect data at a population level it’s quite difficult to collect all these variables”.
Finally, session Chair Amélie Bonnefond, from Lille Pasteur Institute, Lille University, France, and Imperial College London, asked whether they had looked at other “traditional” risk factors for type 2 diabetes.
“We did look at some of the other risk factors for diabetes but we are yet to adjust for them,” Mr Ranchagoda said, adding: “This is a preliminary analysis but we do intend to do that in the future.”
The study is supported by the EFSD Future Leaders Mentorship Programme.
No relevant financial relationships declared.
EASD Virtual Meeting 2020: Abstract 153. Presented September 24.