Warm, matter-of-fact scene with tablets and an insulin pen as symbols for the different treatment options in diabetes.
Tablets
Pen / injection
How the drugs
work
A factual overview of
the main drug classes.
For orientation – the choice is always made by the care team.
Why there are so many classes
Blood sugar can be influenced in several places: at the liver’s sugar release, at insulin secretion, at insulin action, at sugar excretion through the kidney, or at digestion. Each drug class works at a different point – which is why they can often be sensibly combined.
Overview of five groups and how they work. Metformin lowers the liver’s sugar output and is usually first choice. SGLT2 inhibitors let excess sugar be excreted via the urine and protect the heart and kidneys. GLP-1 receptor agonists increase insulin release after eating, curb appetite and protect the heart. Sulfonylureas stimulate the pancreas to release insulin but can cause hypos. Insulin replaces or supplements the body’s own insulin.
The main drug classes
Simplified – many further classes and combinations exist
MetforminLowers the liver’s sugar release · usually first choice
SGLT2 inhibitorsSugar is excreted via urine · protects heart & kidneys
GLP-1 receptor agonistsMore insulin after eating, less appetite · protects the heart
SulfonylureasStimulate insulin release · can cause hypos
InsulinReplaces or supplements the body’s insulin · always needed in type 1
The classes in detail
Evidence level: established (mechanisms)
Metformin mainly lowers the liver’s sugar release and improves insulin action. In type 2 it’s usually the first medication, well established, and on its own it barely causes hypoglycaemia.
SGLT2 inhibitors cause excess sugar to be excreted via the urine. Beyond blood sugar, several of these agents protected the heart and kidneys in studies – which is why they’re now also used with corresponding comorbidities.
GLP-1 receptor agonists boost insulin secretion after eating, curb appetite and slow gastric emptying. Many people lose weight on them; some agents also showed cardiovascular protection.
DPP-4 inhibitors work on a related pathway to the GLP-1 drugs, usually as a tablet and weight-neutral.
Sulfonylureas directly stimulate the pancreas to release insulin. They work reliably but – unlike most newer agents – can cause hypoglycaemia.
Insulin replaces or supplements the body’s own insulin. In type 1 it’s always necessary; in type 2 it’s used when other agents are no longer enough.
Key takeaways
- Different drug classes act at different points and can often be combined.
- Metformin is usually first choice in type 2.
- SGLT2 inhibitors and GLP-1 receptor agonists can also benefit heart, kidneys and weight.
- Sulfonylureas and insulin can cause hypoglycaemia.
- The choice is always made by the care team – individual and depending on comorbidities.
Sources
Sources as of: 21 Jul 2026.
- Pharmacological approaches to glycaemic treatment; drug classes and cardiorenal benefits. ADA Standards of Care. diabetesjournals.org
- Medications for type 2 diabetes: classes, effects, hypoglycaemia risk. IQWiG / Gesundheitsinformation. gesundheitsinformation.de
- Overview of diabetes medications and how they act. Diabinfo. diabinfo.de