20 April 2016

Metformin reduces the risk of a person with diabetes dying from heart disease by 30 to 40% compared to sulfonylureas – another class of medicines used to treat type 2 diabetes.

This is the major finding from analysis of 204 studies involving more than 1.4 million people.

The US analysis, designed to assess the benefits and risks of more than a dozen US-approved drugs for lowering blood sugar in type 2 diabetes, puts metformin as the clear winner.

“This is likely the biggest bit of evidence to guide treatment of type 2 diabetes for the next 2 to 3 years,” says lead author Dr Nisa Marurther from John Hopkins University School of Medicine.

Overall, she says the findings are in line with current US recommendations that metformin be used as a first-line therapy.

The real question arises, Dr Maruthur says, when patients and doctors must choose a second drug to be used in combination with metformin.

“The medications all have different benefits and side effects, so the choice of second-line medications must be based on an individual patient’s preferences.”

Among other findings, the study reveals that DPP-4 inhibitors are less effective at lowering blood sugar levels than metformin and sulfonylureas. Examples of DPP-4 inhibitors in Australia are sitagliptin, saxagliptin, vildagliptin, alogliptin and linagliptin.

In terms of side effects, SGLT-2 inhibitors, which work by shuttling excess glucose out of the body through urine, caused yeast infections in 10% of users, a side effect unique to this drug, Dr Maruthur says. Examples of SGLT-2 inhibitors used in Australia are dapagliflozin, canagliflozin, and empagliflozin.

However, SGLT-2 inhibitors, along with another drug class known as GLP-1 receptor agonists (Australian examples are exenatide and liraglutide), helped patients lose weight.

Sulfonylureas, on the other hand, caused weight gain and resulted in the highest rates of hypoglycemia among the oral medications. Examples of sulfonylureas in Australia are glimepiride, gliclazide, glibenclamide and glipizide.

Last Reviewed: 20/04/2016



Diabetes Medications as Monotherapy or Metformin-Based Combination Therapy for Type 2 Diabetes: A Systematic Review and Meta-analysis. Ann Intern Med. Published online 19 April 2016 doi:10.7326/M15-2650