Type 2 diabetes is one of the most common long-term health conditions in the world. It happens when the body cannot use insulin properly or does not make enough of it, causing blood sugar levels to rise.
Over time, high blood sugar can damage the heart, kidneys, eyes, nerves, and other parts of the body. That is why keeping blood sugar under good control is one of the most important goals of diabetes treatment.
For most people with type 2 diabetes, metformin is the first medicine doctors prescribe. It has been used safely for many years and works well for many patients. However, diabetes often gets worse over time, and metformin alone may no longer keep blood sugar at healthy levels. When this happens, doctors need to decide which medicine should be added next.
To answer this question, researchers carried out one of the largest and longest studies of diabetes medicines. The project, known as The GRADE Study, included 5,047 adults with type 2 diabetes from many different racial and ethnic backgrounds. Every participant was already taking metformin before joining the study.
The volunteers were randomly placed into four groups. Each group received one extra medicine in addition to metformin. The medicines studied were sitagliptin, liraglutide, glimepiride, and insulin glargine U-100. Although these medicines lower blood sugar in different ways, they all aim to help the body control glucose more effectively.
The researchers followed the participants for an average of four years. During that time, they regularly checked blood sugar levels to see how long each treatment could keep them within the recommended target range.
The results showed that adding liraglutide or insulin glargine to metformin worked better than the other two options. People taking these treatments were able to keep their blood sugar under control for about six months longer, on average, than those taking sitagliptin. Glimepiride performed a little better than sitagliptin but was still less effective than liraglutide and insulin glargine.
The researchers also found that the results were similar across different groups of people. Age, sex, race, and ethnicity did not make a meaningful difference in how well the medicines worked. This means the findings may apply to a wide range of patients.
Even so, the study also showed how difficult diabetes can be to manage over many years. Nearly three out of every four participants eventually lost good blood sugar control during the study, despite taking metformin and another diabetes medicine. This suggests that better treatments and new approaches are still needed.
The researchers also looked at heart health because people with type 2 diabetes have a higher risk of heart disease. Among the four medicines, liraglutide offered another important advantage. Participants taking this drug were the least likely to develop heart-related problems during the study, making it an attractive option for many patients.
The researchers said no treatment was perfect. While liraglutide and insulin glargine gave the best blood sugar control overall, each medicine has its own benefits, risks, side effects, and costs. Doctors still need to choose treatment based on each person’s health, lifestyle, and medical history.
The study was led by Dr. Henry Burch and colleagues, and the findings were published in The New England Journal of Medicine.
The results provide strong evidence to help doctors and patients make better decisions about diabetes care. As researchers continue searching for improved treatments, these findings offer valuable guidance for millions of people living with type 2 diabetes.
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