Key facts about diabetes medications
- Diabetes treatments target glucose, weight, and cardiovascular risk; most patients require combination therapy over time.
- Medication choice should consider kidney function, comorbidities, weight goals, and hypoglycaemia risk.
- Regular monitoring ensures medications stay effective and safe as the disease progresses.
Medication is central to diabetes care alongside nutrition and physical activity. Understanding how each drug class works, ideal candidates, and potential side effects empowers you to have informed discussions with healthcare professionals and to optimise daily routines around treatment.
Oral glucose-lowering therapies
| Class | Examples | Mechanism | Key advantages | Notable considerations |
|---|---|---|---|---|
| Biguanides | Metformin (IR/ER) | Reduces hepatic glucose output and improves insulin sensitivity | Weight neutral, long track record, cardiovascular benefit | GI upset common; avoid if eGFR < 30 mL/min/1.73 m² |
| SGLT2 inhibitors | Empagliflozin, dapagliflozin, canagliflozin | Inhibit renal glucose reabsorption, promoting urinary glucose excretion | Cardio-renal protection, modest weight loss, low hypoglycaemia risk | Monitor for genital infections, volume depletion, and ketoacidosis |
| DPP-4 inhibitors | Sitagliptin, linagliptin, vildagliptin | Enhance incretin levels to increase insulin release post meals | Weight neutral, well tolerated, oral convenience | Rare pancreatitis cases; adjust dose for renal impairment except linagliptin |
| Sulfonylureas | Gliclazide, glimepiride, glibenclamide | Stimulate pancreatic insulin secretion | Rapid glucose reduction, cost-effective | Higher hypoglycaemia and weight gain risk |
| Thiazolidinediones | Pioglitazone | Improves peripheral insulin sensitivity | Sustained HbA1c lowering, potential cardiovascular benefit | May cause weight gain, edema, or exacerbate heart failure |
Injectable therapies
| Therapy | Examples | Use case | Benefits | Key cautions |
|---|---|---|---|---|
| GLP-1 receptor agonists | Semaglutide, liraglutide, dulaglutide, tirzepatide (dual GIP/GLP-1) | For patients needing substantial HbA1c reduction and weight loss | Promote satiety, reduce cardiovascular events, low hypoglycaemia risk | GI symptoms common initially; avoid in history of medullary thyroid carcinoma |
| Basal insulin | Glargine, detemir, degludec, NPH | When oral/injectable agents insufficient or contraindicated | Flexibility to reach fasting targets, well understood dosing | Requires glucose monitoring, risk of hypoglycaemia and weight gain |
| Prandial insulin | Aspart, lispro, glulisine | For postprandial control in advanced disease or type 1 diabetes | Fine-tunes meal-related spikes, adaptable to carbohydrate counting | Needs multiple daily injections, carbohydrate education essential |
Combination therapy strategies
- Metformin foundation: Most regimens keep metformin as a base unless contraindicated.
- Dual therapy: Add SGLT2 inhibitor or GLP-1 RA for patients with cardiovascular or renal disease; sulfonylurea or DPP-4 inhibitor for cost-sensitive individuals.
- Triple therapy: Combine agents with complementary mechanisms (e.g., metformin + SGLT2 inhibitor + DPP-4 inhibitor) before moving to insulin.
- De-escalation: Consider reducing sulfonylureas when GLP-1 RA or insulin is initiated to minimise hypoglycaemia.
Dose titration principles
- Increase doses gradually at 2 to 4 week intervals while reviewing fasting and postprandial readings.
- Educate on recognising hypoglycaemia (sweating, tremors, confusion) when using insulin or sulfonylureas.
- Adjust insulin or secretagogues when carbohydrate intake, exercise levels, or weight change significantly.
- Pause or reduce metformin during acute illness or imaging requiring contrast to limit lactic acidosis risk.
Monitoring schedule
| Interval | Tests or checks | Medication focus |
|---|---|---|
| Every 3 months | HbA1c, review of glucose logs, weight, blood pressure | Evaluate overall regimen efficacy |
| Every 6 months | Renal panel, electrolytes, cholesterol profile | Essential for metformin, SGLT2 inhibitors, and cardiovascular risk management |
| Annually | Urine albumin-to-creatinine ratio, liver enzymes, foot and eye exams | Detect complications and medication side effects |
Adverse effects and mitigation
- Metformin GI upset: Titrate slowly, use extended release formulations, take with meals.
- SGLT2 genital infections: Encourage hydration, hygiene practices, and prompt treatment if symptoms arise.
- GLP-1 nausea: Start with low dose, increase after 4 weeks, advise smaller frequent meals.
- Insulin-related hypoglycaemia: Ensure consistent meal timing, teach rule of 15 for low readings, and consider continuous glucose monitors for high-risk patients.
Special populations
| Population | Therapeutic focus | Medication insights |
|---|---|---|
| Chronic kidney disease | Preserve renal function and avoid drug accumulation | Prefer SGLT2 inhibitors (if eGFR ≥ 30), adjust metformin dose, avoid glyburide |
| Atherosclerotic cardiovascular disease | Reduce cardiovascular events | GLP-1 RAs (liraglutide, semaglutide) or SGLT2 inhibitors (empagliflozin) have proven benefit |
| Heart failure | Optimise fluid balance | SGLT2 inhibitors improve outcomes; avoid certain thiazolidinediones |
| Older adults | Simplify regimens and minimise hypoglycaemia | Consider once-daily therapies, de-intensify sulfonylureas, evaluate cognitive status before complex insulin plans |
| Pregnancy planning | Ensure medications are compatible with gestation | Switch to insulin if needed; metformin may be continued under supervision; stop ACE inhibitors or statins |
Medication adherence tips
- Set reminders aligned with meals or daily routines to avoid missed doses.
- Arrange medications using pill boxes or apps that track supply.
- Log glucose readings alongside notes about meals, exercise, or stressors to spot trends.
- Discuss affordability concerns early so alternatives or assistance programmes can be explored.
Frequently asked questions
When should insulin be introduced for type 2 diabetes?
Insulin is typically considered when HbA1c remains above target despite maximised oral and non-insulin injectables, or when symptomatic hyperglycaemia or significant weight loss occurs.
Can I stop metformin once my glucose is controlled?
Metformin continues to offer cardiovascular and metabolic benefits even after control improves. Any decision to stop should be discussed with a healthcare professional.
Are there medications that aid weight loss while lowering glucose?
GLP-1 receptor agonists and SGLT2 inhibitors provide meaningful weight reduction in many patients, making them useful when weight management is a priority.
How do I manage medications during illness?
Follow sick-day rules: maintain hydration, monitor glucose more frequently, pause metformin or SGLT2 inhibitors if dehydrated, and seek medical advice if ketones rise or vomiting persists.
