Know About Diabetics
Last updated on july 3, 2025
Antidiabetic drugs are medications used to treat diabetes mellitus, primarily by lowering blood glucose levels. These drugs are mainly used in Type 2 diabetes, though some are also relevant to Type 1 diabetes as adjunct therapies.
Main Classes of Antidiabetic Drugs
1. Insulins
Examples: Lispro, Aspart, Glargine, Detemir
Mechanism: Replaces or supplements endogenous insulin to lower blood glucose.
2. Biguanides
Example: Metformin
Mechanism: Decreases hepatic glucose production and improves insulin sensitivity.
3. Sulfonylureas
Examples: Glipizide, Glyburide, Glimepiride
Mechanism: Stimulate pancreatic insulin secretion.
4. Meglitinides
Examples: Repaglinide, Nateglinide
Mechanism: Rapid-acting insulin secretagogues, used before meals.
5. Thiazolidinediones (TZDs)
Examples: Pioglitazone, Rosiglitazone
Mechanism: Improve insulin sensitivity via PPAR-γ activation.
6. DPP-4 Inhibitors
Examples: Sitagliptin, Saxagliptin, Linagliptin
Mechanism: Increase incretin levels, enhancing insulin and decreasing glucagon.
7. GLP-1 Receptor Agonists
Examples: Exenatide, Liraglutide, Semaglutide
Mechanism: Mimic incretins, promoting insulin release and slowing gastric emptying.
8. SGLT2 Inhibitors
Examples: Canagliflozin, Dapagliflozin, Empagliflozin
Mechanism: Inhibit glucose reabsorption in kidneys, increasing glucose excretion.
9. Alpha-Glucosidase Inhibitors
Examples: Acarbose, Miglitol
Mechanism: Delay carbohydrate absorption in the intestine.
Antidiabetic Drug Dosages
| Drug Class | Common Drugs | Starting Dose | Max Daily Dose |
|---|---|---|---|
| Biguanides | Metformin | 500 mg once/twice daily with food | 2000–2550 mg/day (divided) |
| Sulfonylureas | Glipizide | 2.5–5 mg once daily | 40 mg/day |
| Glyburide | 2.5–5 mg once daily | 20 mg/day | |
| Glimepiride | 1–2 mg once daily | 8 mg/day | |
| Meglitinides | Repaglinide | 0.5–1 mg before meals | 16 mg/day |
| Nateglinide | 60–120 mg before meals | 360 mg/day | |
| TZDs | Pioglitazone | 15–30 mg once daily | 45 mg/day |
| Rosiglitazone | 4 mg once or twice daily | 8 mg/day | |
| DPP-4 Inhibitors | Sitagliptin | 100 mg once daily | 100 mg/day |
| Saxagliptin | 2.5–5 mg once daily | 5 mg/day | |
| Linagliptin | 5 mg once daily | 5 mg/day | |
| GLP-1 Agonists | Exenatide | 5 mcg BID before meals | 10 mcg BID |
| Liraglutide | 0.6 mg daily → 1.2–1.8 mg | 1.8 mg/day | |
| Semaglutide (inj) | 0.25 mg/week → 0.5–1 mg | 2 mg/week | |
| Semaglutide (oral) | 3 mg/day → 7–14 mg | 14 mg/day | |
| SGLT2 Inhibitors | Canagliflozin | 100 mg once daily | 300 mg/day |
| Dapagliflozin | 5 mg once daily | 10 mg/day | |
| Empagliflozin | 10 mg once daily | 25 mg/day | |
| Alpha-Glucosidase Inh. | Acarbose | 25 mg TID with meals | 300 mg/day |
| Miglitol | 25 mg TID with meals | 300 mg/day | |
| Insulin (Basal) | Glargine, Detemir, Degludec | 10 units or 0.1–0.2 u/kg/day | Titrate based on FBG |
| Insulin (Bolus) | Aspart, Lispro | 4–6 units or carb-based | Individualized |
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Important Considerations – Antidiabetic Drugs
- Metformin: Avoid if eGFR < 30 mL/min; monitor for lactic acidosis.
- Sulfonylureas: Risk of hypoglycemia, especially in elderly or those with irregular meals.
- GLP-1 Agonists: Can cause nausea; slow titration helps. Shown to reduce CV risk.
- SGLT2 Inhibitors: Offer CV and renal protection; caution in dehydration and genital infections.
- TZDs (Pioglitazone): Risk of fluid retention, weight gain, and heart failure; may increase fracture risk.
- DPP-4 Inhibitors: Well tolerated. Avoid saxagliptin in heart failure.
- Insulin: Risk of weight gain and hypoglycemia; dose adjusted based on glucose and carb intake.
Limitations and Side Effects – Antidiabetic Drugs
Metformin (Biguanide)
GI upset (nausea, diarrhea), risk of lactic acidosis, contraindicated in severe renal impairment (eGFR < 30).
Sulfonylureas
Hypoglycemia (especially in elderly or fasting), weight gain, secondary failure over time.
Meglitinides
Short duration of action, multiple daily dosing required, risk of hypoglycemia, weight gain.
Thiazolidinediones (TZDs)
Weight gain, fluid retention, heart failure risk, fracture risk (especially in women), delayed onset of action.
DPP-4 Inhibitors
Generally well tolerated; rare cases of pancreatitis, joint pain. Saxagliptin linked to increased HF risk.
GLP-1 Receptor Agonists
GI effects (nausea, vomiting), injection route, high cost. Pancreatitis risk (rare).
SGLT2 Inhibitors
Genital mycotic infections, urinary tract infections, dehydration, euglycemic ketoacidosis (rare), high cost.
Alpha-Glucosidase Inhibitors
Flatulence, bloating, diarrhea; modest HbA1c reduction, not widely used.
Insulin
Hypoglycemia, weight gain, requires injection and regular monitoring, patient training needed.
Summary of Targets – Antidiabetic Drugs
| Drug Class | Target Area | Primary Effect |
|---|---|---|
| Metformin | Liver | ↓ Glucose production |
| Sulfonylureas / Meglitinides | Pancreas | ↑ Insulin secretion |
| TZDs | Muscle / Fat | ↑ Insulin sensitivity |
| DPP-4 Inhibitors | Gut hormones | ↑ Incretin → ↑ insulin, ↓ glucagon |
| GLP-1 Agonists | Gut / Pancreas | ↑ Insulin, ↓ appetite, ↓ gastric emptying |
| SGLT2 Inhibitors | Kidney | ↑ Glucose excretion in urine |
| Alpha-Glucosidase Inhibitors | Intestine | ↓ Carb absorption |
| Insulin | All tissues | ↑ Glucose uptake |
