People with type 2 diabetes often need more than one medicine to keep their blood sugar under control.
But a large study suggests that the choice of a second medicine may also make an important difference to heart health.
Researchers from Northwestern University found that two commonly used treatments, sulfonylureas and basal insulin, were associated with a higher risk of serious heart and blood vessel problems than a newer group of diabetes medicines. The research was published in JAMA Network Open.
Type 2 diabetes develops when the body does not respond properly to insulin, a hormone that helps move sugar from the blood into cells for energy. As a result, sugar can remain at unhealthy levels in the bloodstream.
Over many years, high blood sugar can damage blood vessels and organs throughout the body. People with diabetes therefore have a greater risk of heart attack, stroke, kidney disease, nerve damage and vision problems.
For many years, metformin has been the usual first medicine prescribed for type 2 diabetes. It is relatively inexpensive, works well for many people and has a long history of use.
But diabetes can become harder to control as time passes. Some people eventually need a second medicine, while others cannot tolerate metformin or may have medical reasons for using a different treatment.
Doctors have many options when another drug is needed. Older medicines such as sulfonylureas and basal insulin remain widely used, partly because they are familiar and can be less expensive than some newer treatments.
The Northwestern researchers wanted to compare the heart safety of these choices in everyday medical care. They studied health records from more than 130,000 adults with type 2 diabetes who began taking a second blood-sugar-lowering medicine after metformin.
The team compared several major groups of diabetes medicines. Their main comparison used DPP-4 inhibitors as the reference group because these medicines were commonly prescribed during the period covered by the study.
The results showed a noticeable difference. People who started a sulfonylurea had about a 36% higher risk of serious heart and blood vessel problems compared with people who started a DPP-4 inhibitor.
The difference was even larger for basal insulin. People who started this treatment had roughly twice the risk of serious cardiovascular problems compared with those taking DPP-4 inhibitors.
The health problems examined by the researchers included heart attacks, strokes, heart failure and amputations. These are especially important complications because heart and blood vessel disease is already a major threat to people living with type 2 diabetes.
The findings were concerning because sulfonylureas and basal insulin were commonly used as second treatments after metformin. The researchers estimated that a large share of patients needing another diabetes medicine received one of these two options.
However, the study does not mean that these medicines are dangerous for every patient or that people should suddenly stop taking them. It was based on health records rather than a trial in which patients were randomly assigned to different drugs, so it can show an association but cannot prove that the medicines directly caused the extra heart problems.
The researchers said doctors may want to consider other treatment choices when appropriate. These include GLP-1 receptor agonists, SGLT-2 inhibitors and DPP-4 inhibitors, although the best choice depends on a person’s health, kidney function, weight, risk of low blood sugar, treatment goals and access to medicines.
Some newer diabetes drugs have also shown important benefits for the heart and kidneys in later research. However, cost and insurance coverage can strongly influence which medicines patients can realistically use.
Lead researcher Dr. Matthew O’Brien said the findings highlight the importance of discussing the advantages and disadvantages of available treatments. Choosing a diabetes medicine should involve more than simply asking how well it lowers blood sugar.
For people with type 2 diabetes, protecting the heart is a major part of long-term care. The study adds evidence that when another medicine is needed after metformin, doctors and patients should consider both blood sugar control and the possible effects on future heart health.
If you care about diabetes, please read studies about Vitamin D and type 2 diabetes, and what you need to know about avocado and type 2 diabetes.
For more health information, please see recent studies about how to eat to prevent type 2 diabetes, and 5 vitamins that may prevent complication in diabetes.
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