Typical age at diagnosis | 10–45 years | 10–45 years | Birth onwards | 1–30 years | After 25 years |
Ketonaemia/diabetic ketoacidosis | Very rare | Very rare | Would not be predicted to occur | Common | Rare except in ketosis-prone subtype |
First-degree relative with DM | Reported in 50–60% | Around 50% (high rate of spontaneous mutations) | Often undiagnosed or reported as IGT/GDM | 2–4% | Around 50% |
Insulin resistance/obesity | Same as non-diabetic population | Same as non-diabetic population | Same as non-diabetic population | Same as non-diabetic population | Common |
Beta-cell antibodies | Negative | Negative | Negative | Positive at diagnosis in 80–90% | Negative |
C-peptide after 3 years from diagnosis | Normal range | Normal range | Normal range | Low or undetectable in majority | High normal |
First-line drug treatment | Low-dose sulphonylurea | Metformin if renal function allows | None | Insulin | Metformin |