There Are Not Two Kinds of Diabetes, and Being Put in the Wrong Box Changes the Treatment

The clue is the pattern rather than any single test: an adult who is not overweight, whose control deteriorates faster than it should, and who may have another autoimmune condition such as thyroid disease. Antibody testing settles it, and it is ordered less often than it should be.

What is MODY?

Maturity-onset diabetes of the young is the one worth knowing about because the answer can be so much better than the default.

MODY is caused by a mutation in a single gene, and it is inherited in a straightforward dominant pattern, which is why the family tree is the giveaway. Diabetes in a parent, a grandparent, a sibling, diagnosed young, in people who are not overweight, is the classic picture.

Here is why the label matters. Some MODY subtypes respond extremely well to sulfonylurea tablets, better than they respond to insulin. There are documented cases of people who injected insulin for years, were genetically tested, and moved to a tablet. Another common subtype produces mild, stable, lifelong glucose elevation that frequently needs no treatment at all and does not carry the usual complication risk.

Being told you may not need the injections you have been giving yourself since adolescence is a rare kind of medical news. It only happens if somebody thinks to test.

Does the ADA guidance help sort this out?

It has been moving in that direction, and the 2026 Standards of Care went further on the autoimmune side.

The guidance now treats a confirmed single IA-2 autoantibody as warranting monitoring similar to stage 2 disease, which is a meaningful tightening of how early autoimmune diabetes gets tracked. The same edition also, for the first time, supports GLP-1 class therapy in adults with type 1 diabetes and a BMI above 30, an acknowledgement that people with type 1 also live with obesity and were being left out of a drug class that could help them.

Both changes point the same way: away from two tidy boxes and toward describing what is actually happening in a given pancreas.

What should you do if the label does not fit?

Ask, specifically, and ask early.

If you were diagnosed with type 2 as an adult, are not overweight, have another autoimmune condition, or found that tablets stopped working within a few years, it is reasonable to ask whether autoantibody testing is warranted. If diabetes runs through your family in every generation and was diagnosed young in people of normal weight, it is reasonable to ask about genetic testing for MODY.

Neither request is exotic and neither is a challenge to your doctor. The type determines the treatment, and roughly one in five adults in this region is living with some form of this condition. Getting the category right is not a technicality. It is the difference between the right drug and years of the wrong one.