Rosiglitazone is a medicine developed to help people with type 2 diabetes control their blood sugar.
However, researchers from the Yale School of Public Health found stronger evidence that the drug may increase the risk of serious heart problems.
Type 2 diabetes develops when the body does not use insulin properly or cannot produce enough insulin to keep blood sugar at a healthy level.
Over time, poorly controlled blood sugar can damage blood vessels and increase the risk of heart disease, kidney disease, nerve damage and vision problems.
Rosiglitazone belongs to a group of diabetes medicines called thiazolidinediones. It works mainly by making the body’s cells more sensitive to insulin, allowing them to use glucose from the blood more effectively.
Although the medicine can lower blood sugar, concerns about its effects on the heart have existed for years. Earlier reports linked rosiglitazone to cardiovascular problems, leading European regulators to suspend the medicine and U.S. regulators to place restrictions on its use.
Scientists continued to debate the size of the risk, especially whether rosiglitazone increased heart attacks. One reason for the uncertainty was that many earlier analyses used only summary results from clinical trials rather than detailed information about individual patients.
Researchers at Yale therefore carried out a much larger review using both individual patient information and summary trial data. They examined more than 130 clinical trials involving over 48,000 adults.
The trials compared rosiglitazone with another treatment or an inactive placebo. To be included in the analysis, studies generally needed to follow participants for at least 24 weeks, allowing researchers to examine cardiovascular problems that developed during treatment.
The results raised further concerns about the drug’s safety. In analyses using detailed patient-level information, rosiglitazone was associated with a 33% higher risk of a combined group of serious events compared with control treatments.
These events included heart attacks, heart failure, deaths from cardiovascular causes and deaths from other causes. Researchers recorded 274 such events among 11,837 people receiving rosiglitazone, compared with 219 events among 9,319 people in control groups.
Heart failure was one of the clearest concerns. Heart failure occurs when the heart cannot pump blood effectively enough to meet the body’s needs, which can cause tiredness, shortness of breath and fluid buildup in the legs or lungs.
This risk is especially important for people with type 2 diabetes because diabetes itself raises the likelihood of developing cardiovascular disease. A diabetes treatment therefore needs to be judged not only by how well it lowers blood sugar but also by its effects on the heart and other organs.
The researchers also highlighted a broader problem in medical research. Their analysis showed how access to detailed information from clinical trials can change scientists’ understanding of a medicine’s safety.
When researchers have individual patient data, they can examine outcomes more carefully and use consistent definitions across studies. Greater sharing of clinical trial data could therefore help doctors, researchers and regulators identify important drug risks more accurately.
The Yale-led research was published in the BMJ. It provided one of the most comprehensive assessments of rosiglitazone’s cardiovascular safety and added to years of debate about the medicine.
The findings do not mean that blood sugar control is unimportant. Keeping diabetes under control remains essential, but modern diabetes care increasingly considers a medicine’s wider effects, including its impact on the heart, kidneys, body weight and risk of dangerously low blood sugar.
People who take rosiglitazone should not stop or change their medicine without speaking with a healthcare professional. A doctor can consider a person’s blood sugar levels, heart health, other medical conditions and available alternatives before deciding whether a treatment should be continued or changed.
The study offers a broader lesson for diabetes treatment: lowering a laboratory number is only part of the goal. The safest treatment is one that controls blood sugar while also protecting a person’s overall health over the long term.
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