An inexpensive type 2 diabetes drug that has been around for more than 15 years works just as well and has fewer side effects than most new and more expensive classes of medication used to control the chronic disease.
Although there are numerous options in oral medications for type 2 diabetes, an older drug - metformin - may be the best first-line option. There are 11 classes of medication for adult-onset diabetes that are approved to treat high blood sugar. Nine of these classes of medications have been available since 1995 and new classes of have been approved since then. Most people with type 2 diabetes need to take more than one medication to adequately control their blood sugar levels. The most common serious side effect from any of these blood sugar-lowering medications is hypoglycaemia, or low blood sugar levels. Other common side effects include gastrointestinal problems, such as nausea or diarrhoea.
Researchers in America wanted to know if the newer drugs were any better than the older crop. The research team also looked for the first time at the efficacy of two-drug combinations to treat the chronic disease, which has become increasingly common with more than one-third of diabetes patients needing multiple medications. They reviewed a total of 166 previously published medical studies that examined the effectiveness and safety of diabetes drugs, as well as their impact on long-term outcomes including death, cardiovascular disease, kidney disease and nerve disease. The studies included six classes of medication: metformin (Glucophage, Fortamet and others); second-generation sulfonylureas (Amaryl, Glucotrol and others); thiazolidinediones (Avandia and Actos); meglitinides (Starlix and Prandin); dipeptidyl peptidase-4 (DPP-4) inhibitors (Januvia and Onglynza); and glucagon-like petide-1 (GLP-1) receptor agonists (Byetta and Victoza). In general, most of the medications lowered haemoglobin A1C levels (a measure of long-term blood sugar control) by one percentage point. The American Diabetes Association recommends that most people with diabetes keep their A1C levels below 7 percent, so a drop of one percentage point is clinically meaningful. While most drugs reduced blood sugar similarly, metformin was consistently associated with fewer side effects.
The researchers also found that adding a second medication improves blood sugar control, but that no combination of medications appeared to offer significant benefits over another. Metformin, which was associated with a high risk of diarrhoea, appeared to have the lowest side-effect profile. And, it also costs the least. As a class of medications, thiazolidinediones have come under intense scrutiny because of serious potential side effects, and this analysis confirmed that weight gain, fractures and an increased risk of congestive heart failure are associated with thiazolidinediones. Although heart attacks have also been linked to the class of medications, this analysis was not able to confirm or refute an increased risk of heart attack. Sulfonylureas and meglitinides were associated with a high risk for hypoglycaemia.
The researchers suggest that metformin is probably the best first-line choice since it has fewer side effects and also costs less.