Patients with type 2 diabetes have a greater risk of developing cardiovascular (CVD) disease compared to the general population even when CVD risk factors are optimally controlled.

The research published in the American Heart Association's journal Circulation found that only 6% of participants with type 2 diabetes had all five risk factors within target range. Even when all five cardiovascular risk factors were optimally controlled, people with type 2 diabetes still had a 21% higher risk for CVD and 31% higher risk for heart failure hospitalisation than people without diabetes.

Researchers analysed data between 2006 and 2015 using two sources from the  Clinical Practice Research Datalink (CPRD) and the Scottish Care Information-Diabetes (SCI-Diabetes) dataset with linkage to hospital and mortality data. More than 101,000 people with type 2 diabetes were identified and matched with nearly 379,000 people without diabetes in CPRD and nearly 331,000 with type 2 diabetes in SCI-Diabetes.

Alison Wright, first author and research associate at the Centre for Pharmacoepidemiology and Drug Safety at the University of Manchester, said: "Previous studies have shown that people with type 2 diabetes had little or no excess risk of cardiovascular disease events or death when all risk factors are optimally controlled.

"Our team sought to determine how the degree of risk factor control in people with type 2 diabetes impacted CVD risk and mortality compared to people with type 2 diabetes who had all risk factors optimally controlled and to people who do not have type 2 diabetes."

Need to reduce the impact of type 2 diabetes on future CVD events

Researchers focused on five cardiovascular risk factors: blood pressure, smoking, cholesterol, triglycerides and blood glucose, and examined the association to future cardiovascular events and death among these risk factors that were optimally controlled. Additionally, they examined if the presence of cardiorenal (heart and kidney) disease impacted these connections.

The association among the number of elevated risk factors and CVD event risk was stronger in people with type 2 diabetes who did not also have cardiorenal disease.

Dr Wright added: "People with type 2 diabetes should be treated for cardiovascular risk factors as early as possible, regardless of whether they have cardiovascular disease or not. There is real potential here to reduce the overall impact of type 2 diabetes on future cardiovascular events, especially for patients with type 2 diabetes who have not yet been diagnosed with CVD."

While researchers noted that this research demonstrated the importance of risk factor control overall, future research will explore which individual factors have the greatest impact on cardiovascular risk, and, therefore, are the most important to target with interventions. 

A limitation of this study is that it is an observational study, using data from primary care medical records that may be incomplete. Therefore, the data may not provide the full picture of the health status for these patients.