Study proposes five types of diabetes, not two

Adults with diabetes could benefit from better treatment if the condition was categorized into five types, rather than just two. This is the conclusion of a new study published in The Lancet Diabetes & Endocrinology.

The research was led by Prof. Leif Groop, of the Lund University Diabetes Centre in Sweden and the Institute for Molecular Medicine Finland in Helsinki.

Excluding gestational diabetes — diabetes that develops during pregnancy — there are two main types: type 1 and type 2.

In type 1 diabetes, the beta cells of the pancreas — which produce insulin, the hormone that regulates blood sugar levels — are mistakingly attacked and destroyed by the immune system.

Type 2 diabetes is the most common form, accounting for around 90–95 percent of all cases. This occurs when the body’s cells stop responding to insulin, or the beta cells are unable to produce sufficient amounts of the hormone.

In both forms of the condition, blood sugar levels can become too high — a condition known as hyperglycemia. Unless controlled, this can lead to a number of complications, including kidney disease, cardiovascular disease, and nerve damage.

A diabetes diagnosis is normally made using the fasting plasma glucose (FPG) test or the A1C test. The FPG test assesses a person’s blood glucose level at a single time point, while the A1C test measures average blood glucose levels over the previous three months.

When it comes to determining which type of diabetes a person has, healthcare professionals might look for diabetes-related autoantibodies in the blood. These are proteins produced by the immune system that can attack the body’s own cells.

The presence of such autoantibodies is an indicator of type 1 diabetes. If a person does not have these autoantibodies, they are considered to have type 2 diabetes.

But, as Prof. Groop and colleagues note, the classification guidelines for diabetes have not been updated for 20 years — despite increasing evidence that diabetes has high heterogeneity.

“Diabetes is a group of chronic metabolic disorders,” says Dr. Rob Sladek, of the McGill University and Génome Québec Innovation Centre in Canada, in an editorial linked to the study, “that share the common feature of hyperglycemia, meaning that, in principle, diabetes can be diagnosed via measurement of a single blood.