Adult-onset diabetes cases should be classified into five different types, rather than just type 1 or 2, according to researchers from Scandinavia.
Doing so might help to better tailor early treatment for patients and could represent a first step towards precision medicine in the disease, they said.
“More accurately diagnosing diabetes could give us valuable insights into how it will develop over time”
The five types they identified in their study had different characteristics and were associated with different complications, which they said illustrated the varied treatment needs of diabetes patients.
The researchers highlighted that diabetes rates were increasing worldwide, but its classification had not been updated for 20 years and still mainly relied on measuring blood glucose levels.
In particular, they noted that few attempts had previously been made to explore the distinctions in type 2 diabetes, which comprised 75-85% of cases and was known to be highly variable.
The study used four cohort studies including people over the age of 18 years who had been recently diagnosed with diabetes, totalling 14,775 patients across Sweden and Finland.
The authors analysed six factors – age at diagnosis, body mass index, HbA1c, successful functioning of insulin-producing cells, insulin resistance, and auto-antibodies associated with autoimmune diabetes.
“This research takes a promising step toward breaking down type 2 diabetes in more detail”
They also carried out genetic analyses, and compared disease progression, treatment, and development of diabetic complications for each type of diabetes.
Analysing the six measures in a cohort of 8,980 adults at first, the study authors identified one autoimmune type of diabetes and four distinct subtypes of type 2 diabetes.
They then tested them across three more cohorts of patients consisting of 5,795 people and found that the five different disease profiles were also present in these patients.
These five types of diabetes were distinct and included three severe and two mild forms of the disease, according to the researchers writing in the journal The Lancet Diabetes and Endocrinology.
- Cluster 1 = severe autoimmune diabetes
- Cluster 2 = severe insulin-deficient diabetes
- Cluster 3 = severe insulin-resistant diabetes
- Cluster 4 = mild obesity-related diabetes
- Cluster 5 = mild age-related diabetes
Among the severe forms, there was one group with severe insulin resistance and a significantly higher risk of kidney disease than the other types, and a group of relatively young, insulin-deficient individuals with poor metabolic control but no auto-antibodies.
The other severe group were insulin-deficient patients who had auto-antibodies associated with autoimmune diabetes, a form of diabetes formerly classified under type 1 diabetes or latent autoimmune diabetes in adults.
The most common form identified was one of the more moderate forms of diabetes, which was seen in older people and affected 39-47% of patients. The other mild form of diabetes was mainly seen in obese individuals and affected 18-23% of patients.
All five types were also genetically distinct, with no mutations associated with all forms of the disease, supporting the idea that they were not simply different stages of the same disease.
Future research will be needed to test and refine the five types of the disease by including biomarkers, genotypes, genetic risk scores, blood pressure and blood lipids, said the researchers.
As reported last year by Nursing Times, UK researchers have previously warned that the health of some diabetes patients was being put at risk due to the failure of clinicians to recognise that they have a third subtype of the condition.
- Patients ‘at risk’ over failure to recognise diabetes subtype
- Developing type 1 diabetes ‘as common’ in adults as children
- Weight loss programme in primary care ‘reverses type 2 diabetes’
Lead author of the new study Professor Leif Groop, from Lund University in Sweden, said: “Evidence suggests that early treatment for diabetes is crucial to prevent life-shortening complications.
“More accurately diagnosing diabetes could give us valuable insights into how it will develop over time, allowing us to predict and treat complications before they develop,” said Professor Leif.
“Existing treatment guidelines are limited by the fact they respond to poor metabolic control when it has developed, but do not have the means to predict which patients will need intensified treatment,” he said.
“This study moves us towards a more clinically useful diagnosis, and represents an important step towards precision medicine in diabetes,” he added.
Dr Emily Burns, head of research communications at Diabetes UK, noted that finding diabetes subtypes would help “personalise treatments and potentially reduce the risk of diabetes-related complications”.
“This research takes a promising step toward breaking down type 2 diabetes in more detail, but we still need to know more about these subtypes before we can understand what this means for people living with the condition,” she said.
“For example, whether we’d find the same subtypes in people of different ethnicity or nationality,” she added.
- Diabetes management 1: disease types, symptoms and diagnosis
- Diabetes management 2: long-term complications due to poor control
- Diabetes management 3: the pathogenesis and management of diabetic foot ulcers