Rates of diabetes are increasing worldwide, representing a significant cause of ill health worldwide. Today, about 425 million people around the world have diabetes.
Diabetes is currently divided into type 1 diabetes, type 2 diabetes and a number of rare diabetes subtypes. Majority of the cases (85–90 %) are diagnosed as type 2 diabetes.
“Current diagnostics and classification of diabetes are insufficient and unable to predict future complications or choice of treatment,” says lead author of the study, Professor Leif Groop from Lund University Diabetes Centre (LUDC) and University of Helsinki.
The researchers were able to distinguish five distinct diabetes subtypes that differ from today’s classification. The new classification is based on six measurements that reflect key aspects of the disease: age at diagnosis, body mass index (BMI), long-term glycaemic control, insulin resistance, insulin secretion, and presence of auto-antibodies associated with autoimmune diabetes.
“Today, diagnoses are performed by measuring blood sugar. A more accurate diagnosis can be made by also considering the factors accounted for in our study. This is the first step towards personalised treatment of diabetes,” explains Groop.
The major difference from today’s classification is that type 2 diabetes actually consists of several subgroups. Each group has significantly different patient characteristics and risk of diabetic complications, especially diabetic kidney disease. All five types of diabetes were also genetically distinct.
The findings of the international research group were based on ANDIS, a study covering all newly diagnosed diabetics in southern Sweden, two other Swedish cohorts and the Diabetes Registry Vaasa (DIREVA) study from Finland. Almost 15 000 diabetes patients participated in the study.
The researchers subsequently repeated the analysis in a further three studies from Sweden and Finland. The corresponded with the analysis from ANDIS study surprisingly well. The only difference was that there were more patients with mild age-related diabetes in Finland than in Skåne.
“The patients with severe insulin-resistant or severe insulin-deficient diabetes have the most to gain from the new diagnostics as they are the ones who are currently most incorrectly treated,” says Department head Tiinamaija Tuomi from the Helsinki University Central Hospital.
“This will enable earlier treatment to prevent complications in patients who are most at risk of being affected.”
The study was coordinated by the Lund University Diabetes Center. The study included Finnish researchers from University of Helsinki (Institute for Molecular Medicine Finland FIMM, HiLIFE), Vaasa Central Hospital, Helsinki University Central Hospital and Folkhälsan Research Center.
New diabetes classification
SAID (severe autoimmune diabetes): essentially corresponds to type 1 diabetes and LADA (latent autoimmune diabetes in adults), and is characterised by onset at young age, poor metabolic control, impaired insulin production and the presence of GADA antibodies.
SIDD (severe insulin-deficient diabetes): includes individuals with high HbA1C, impaired insulin secretion and moderate insulin resistance. Group 2 had the highest incidence of retinopathy.
SIRD (severe insulin-resistant diabetes): is characterised by obesity and severe insulin resistance. Group 3 had the highest incidence of kidney damage – the secondary disease producing the highest costs to society.
MOD (mild obesity-related diabetes): includes obese patients who fall ill at a relatively young age.
MARD (mild age-related diabetes): is the largest group (about 40%) and consists of the most elderly patients.
Department head Tiinamaija Tuomi, HUS & University of Helsinki
Professor Leif Groop, University of Helsinki & University of Lund
Emma Ahlqvist, Petter Storm, Annemari Käräjämäki*, Mats Martinell*, Mozhgan Dorkhan, Annelie Carlsson, Petter Vikman, Rashmi B Prasad, Dina Mansour Aly, Peter Almgren, Ylva Wessman, Nael Shaat, Peter Spégel, Hindrik Mulder, Eero Lindholm, Olle Melander, Ola Hansson, Ulf Malmqvist, Åke Lernmark, Kaj Lahti, Tom Forsén, Tiinamaija Tuomi, Anders H Rosengren, Leif Groop. Novel subgroups of adult-onset diabetes and their association with outcomes: a data-driven cluster analysis of six variables. Lancet Diabetes and Endocrinology