Antidiabetic Drugs | Benefits and Drawbacks

oral antidiabetic drugs


The purpose of antidiabetic drugs is clear – to lower blood glucose levels. There are many different antidiabetic drug classes. Here, we talk about the advantages and disadvantages of each of these major drug classes.

In today’s review, we talk about the benefits and drawbacks of:

  • Sulfonylureas – glyburide, gliclazide
  • Biguanides – metformin
  • Alpha-glucosidase inhibitors – acarbose, miglitol
  • Thiazolidinediones – pioglitazone
  • DPP-4 inhibitors – linagliptin, saxagliptin
  • Glycosurics– canagliflozin, dapagliflozin

When we talk about the benefits and drawbacks of these medicines, we often need to factor in their effects on weight, cholesterol / triglycerides, cost, dosing and other side effects. Many of these drugs offer complex solutions. It’s not always obvious what drug / drug class may work best for the patient.

As part of your clinical pharmacy exam, you will be expected to know about each of these drug classes – how they work and how best to weigh the risk:benefit ratio in accordance with the best available evidence and considered practice.

That said, let’s get started.

Antidiabetic Drugs Comparison

Whilst there are several other antidiabetic drug classes, here we review four of the most commonly used classes – biguanides (metformin), sulfonylureas, alpha-glucosidase inhibitors and thiazolidinediones.

Beneath the table you can find more details on other drug classes.

Drug ClassAdvantagesDisadvantages
MetforminNot linked to weight gain

Can cause weight loss

Low risk of hypoglycaemia

Positive effect on LDL levels

Lowers triglycerides

No impact on blood pressure

Relatively cheap

Greater risk of GI effects

Higher risk of lactic acidosis **

Risk of vitamin B12 deficiency

Inconvenient dosing

Metallic taste

SulfonylureasNo impact on LDL levels

No impact on blood pressure

Fast onset of action


Low risk of GI effects

Convenient dosing

5-10lbs avg. weight gain

Higher risk of hypoglycaemia

Alpha-glucosidase inhibitorsLower risk of hypoglycaemia compared to sulfonylureas

No risk of weight gain

Lowers triglycerides

No impact on cholesterol

Less impact on reducing glycated haemoglobin levels


Inconvenient dosing

Risk of GI effects – though lower than metformin

ThiazolidinedionesIncreases HDL cholesterol

Lowers triglyceride levels ***

Convenient dosing

Lower risk of hypoglycemia

5-10lbs avg. weight gain

Increased risk of bladder cancer ****

Increased risk of heart failure

Increases LDL levels

Hepatotoxicity monitoring

Increased risk of fractures


** Risk higher in heart failure, liver disease, alcoholism and metabolic acidosis.

*** Avandia (rosiglitazone) may increase triglyceride levels.

**** Actos (pioglitazone) only.

Glycosurics and DPP-4 Inhibitors

Two other antidiabetic drug classes worth discussing are the glycosurics – drugs that block glucose reuptake from the renal tubules leading to a loss of glucose in urine – and the DPP-4 inhibitors, which work by blocking the enzyme dipeptidyl peptidase-4; an enzyme that otherwise degrades GLP-1 (a metabolic hormone that decreases blood glucose levels).

Glycosurics– examples of which include dapagliflozin and canaglifozin – are associated with mild weight loss which, as we have learned, is an uncommon effect amongst these drug classes. Glycosurics also carry a lower risk of hypoglycemia compared to other drug classes.

Dipeptidyl peptidase-4 inhibitors – examples of which include linagliptin, sitagliptin and saxagliptin – are associated with the following effects:

  • Increased risk of hypoglycemia when DPP-4 inhibitors are taken alongside sulfonylureas
  • Nasopharyngitis and headache are also commonly reported
  • The FDA has issued a warning that DPP-4 inhibitors can lead to severe joint pain
  • Saxagliptin is associated with an increased risk of heart failure
  • All DPP-4 inhibitors increase the risk of acute pancreatitis
  • Little impact on weight

Here we’ve talked about the benefits and drawbacks of antidiabetic drugs.

As we have learned, there are many factors to consider. This review is not intended to be exhaustive, but it does provide a platform onto which you can build your knowledge further.

During your NAPLEX exam, or other clinical pharmacy exam, you will be expected to have a thorough and rounded knowledge of this important corner of medicine. It’s essential that you are familiar with not just how these medicines work, but how they can impact the patient – weighing both benefits and risks accordingly.

If you would like to test your knowledge of antidiabetic drugs pharmacology and its clinical implications, we have put together a comprehensive range of questions as part of our online course. Register today to receive instant access to your online learning portal.


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