Separating adult-onset diabetes into five different types, rather than just type 1 or type 2, might help to better tailor early treatment for patients, according to a new analysis.
The five types of the disease found in the study, published in The Lancet Diabetes & Endocrinology journal, had different characteristics and were associated with different complications, and responded to different treatment strategies.
Rates of diabetes are increasing worldwide, faster than for any other disorders, but the medical classification of diabetes has not been updated for 20 years and mainly relies on measuring blood glucose levels.
While type 1 diabetes is generally diagnosed in childhood and caused by the body not producing enough insulin, type 2 diabetes occurs when the body cannot produce enough insulin to meet the increased demands imposed by obesity and insulin resistance, and typically occurs later in life. Most diagnosed cases of diabetes are type 2 (75-85%).
‘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,’ says lead author of the study Professor Leif Groop, Lund University Diabetes Centre (LUDC), Sweden, and Institute for Molecular Medicine Finland (FIMM). ‘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. This study moves us towards a more clinically useful diagnosis, and represents an important step towards precision medicine in diabetes.’
The five distinct types of diabetes included three severe and two milder forms of the disease.
Among the severe forms, one group was characterised as severe insulin-resistant diabetes with a significantly higher risk of kidney disease. Another group of relatively young individuals had poor metabolic control but no auto-antibodies and were classed as severe insulin-deficient diabetes. The other severe group were insulin-deficient patients who had auto-antibodies associated with autoimmune diabetes, formerly called latent autoimmune diabetes in adults (LADA), a form of type 1 diabetes.
The most common form of the disease was one of the more moderate forms of diabetes, which was seen in elderly people and affected 39-47% of patients (mild age-related diabetes). The other mild form of diabetes (mild obesity-related diabetes) was mainly seen in obese individuals and affected 18-23% of patients.
All five types of diabetes were also genetically distinct, supporting the idea that the five types of diabetes are not simply different stages of the same disease.
Lastly, the authors looked at the types of treatments being given to each group of patients and found that many were not being given appropriate treatment. For example, patients in the first two groups would benefit from insulin sooner after disease onset, suggesting that traditional classification of diabetes is unable to tailor treatment to the underlying characteristics of diabetes.
Ahlqvist E, et al. Lancet Diabetes Endocrinol 1 March 2018.