Also called type 2 diabetes mellitus, T2D, adult-onset diabetes · Reviewed
Definition:Type 2 diabetes is a long-term disease in which blood glucose (blood sugar) is higher than normal because the body does not make enough insulin or does not use it well. MedlinePlus says it usually starts with insulin resistance, and that over time the body cannot make enough insulin to keep up. It is the most common form of diabetes.
How it is diagnosed
Diabetes cutoffs from the NIDDK diagnosis page (source: American Diabetes Association)
Test
Diabetes result
A1C
6.5% or above
Fasting plasma glucose (8 hours without food)
126 mg/dL or above
Glucose 2 hours after a glucose drink
200 mg/dL or above
Random glucose, used when there are symptoms
200 mg/dL or above
NIDDK notes that these tests confirm diabetes but do not say which type. MedlinePlus says many people have no symptoms at first, which is why the numbers matter.
Labels written around it
Metformin (a biguanide) is approved, with diet and exercise, for type 2 diabetes in adults and children 10 and older, and its patient leaflet says it is not for type 1 diabetes.
GLP-1 medicines such as Ozempic, Victoza and Trulicity, and Mounjaro, are approved for type 2 diabetes, and several also to lower the risk of major heart events in people with it.
SGLT2 inhibitors such as Jardiance and Farxiga treat type 2 diabetes, and their labels say they are not for blood sugar control in type 1.
Why it matters for your log
An A1C reflects about three months of blood sugar, so it only makes sense next to what changed in those months. Dose dates, dose changes and glucose readings in one place let you line up each A1C with the doses behind it.
General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
The NIDDK table, from the American Diabetes Association, lists an A1C of 6.5% or above as diabetes. A fasting glucose of 126 mg/dL or above also counts.
What is the difference between type 1 and type 2 diabetes?+
In type 1 the immune system destroys the cells that make insulin, so the body makes little or none. In type 2 the body still makes insulin but does not make enough or use it well.