Researchers from Scotland-based University of Dundee have helped identify distinct forms of type 2 diabetes in South Asians, a development with important implications for prognosis and management of diabetes.
The majority of knowledge surrounding diabetes and its cardiovascular complications has been accumulated from studying white populations with Western European ancestry, despite the fact that diabetes in Europeans is very different from Asians. This is referred to as the ‘Asian Indian Phenotype’.
This situation led to the creation of INSPIRED, a £7 million Dundee-led project that seeks to improve diabetes outcomes in India by working to better understand who gets diabetes, how it progresses, why some people respond better than others to treatments, and why some patients develop complications.
INSPIRED sees the University of Dundee’s expertise in the use of medical records to deliver improved care in diabetes ‘twinned’ with a large patient data set covering over 450,000 Indian diabetic patients.
In their latest paper, published in BMJ Open Diabetes Research and Care, the INSPIRED team show for the first time that type 2 diabetes in the Asian Indians can be classified into four distinct phenotypic clusters. One of these – Combined Insulin Resistant and Deficient Diabetes (CIRDD) – is of particular importance as it is characterised by difficult-to-control hyperglycemia and increased risk of both diabetes eye and kidney disease.
Professor Colin Palmer, of University of Dundee’s School of Medicine, said, “These findings appear to be unique to Indians as they differ significantly from the findings published earlier in the European population. We recently reported that Asians respond better to DPP4 inhibitors and SGLT2 inhibitors. The findings of this study confirm the greater insulin secretory defect and the younger age at onset of diabetes in South Asians.”
Classifying Asian Indians with type 2 diabetes into phenotypic clusters provides insights into the pathophysiological processes driving diabetes in this ethnic group, which could help in predicting the risk of complications and in focusing more attention on individuals with the highest risk of developing complications.
The Asian Indian Phenotype is characterised by high levels of abdominal fat and increased insulin resistance even at low levels of body-mass index (BMI) and this has been suggested to be the main reason for increased propensity to develop type 2 diabetes at a younger age. Recent studies from the INSPIRED team showed that beta-cell dysfunction occurs quite early and rapidly in Asian Indians.
The four clusters identified are Severe Insulin Deficient Diabetes (SIDD), Insulin Resistant Obese Diabetes (IROD), Combined Insulin Resistant and Deficient Diabetes (CIRDD) and Mild Age-Related Diabetes (MARD). SIDD and MARD correspond to the clusters identified in the Europeans populations, while the other two are novel subgroups unique to the South Asians.
The characteristics of the clusters did not differ when split by gender and duration of diabetes, which shows the stability of the clusters.