Predicting the chances of someone developing a disease is not an exact science, but researchers from Pittsburgh say comparing the ratio of harmful factors with protective ones may give a more accurate picture.

In a study to find out how heart disease risks in patients with type 1 diabetes can be better assessed, researchers from the University of Pittsburgh Graduate School of Public Health looked to evidence collected between 1950 and 1980.

Diabetes affects 25.8 million Americans according to figures from a 2011 fact sheet published by the Centers for Disease Control and Prevention (CDC). And figures from 2004 show that adults with diabetes are between two and four times more likely to die from heart disease than those without diabetes.

The CDC fact sheet explains that type 1 diabetes is usually diagnosed in children and young adults. The body’s immune system destroys pancreatic beta cells. These are the only cells in the body that make insulin, the hormone that regulates blood glucose. People with type 1 diabetes must have insulin, delivered by injection or a pump, to survive.

In adults, type 1 diabetes accounts for approximately 5% of all diagnosed cases of diabetes, according to the CDC. And there is no known way to prevent people developing type 1 diabetes.