Duration of diabetes and high heart attack risk

Men who have had type 2 diabetes for a decade or more face the same risk of heart attack as those who have already had a prior heart attack. In other words, when a man develops type 2 diabetes could determine his risk of a heart attack.

Prior research had indicated that the risk of heart disease in people with type 2 diabetes was the same as in people who had had a previous heart attack. But research indicates that the risk really does have more to do with timing.

The study followed 4,045 men aged 60 to 79 years for nine years in Britain. They found a higher risk of heart attacks and death in all those who had diabetes, compared to men who didn't have the illness. Risk rose along with duration of disease - compared to men without diabetes, men who had early-onset diabetes (in this case, for an average of 17 years or more) had 2.5 times the risk of a heart attack. It was noted that level of risk was equal to that of men with a prior history of heart attack.

Men who had late-onset diabetes (an average of five years with the disease) had a 54 percent higher risk of a heart attack or of dying. The risk for cardiovascular problems rose significantly after a man had had diabetes for eight years. None of these risk differences were affected by more typical risk factors for heart attack, such as inflammation of the arteries.

The bottom line was that men who had had diabetes longer, in other words early-onset diabetes diagnosed before age of 60 years, had more heart attacks and more events. This made them look equivalent to patients who had had a prior heart attack and no diabetes.

Cardiac risk in women doesn't begin to accumulate until later in life due to the protective effects of oestrogen, so the effect of duration of diabetes may or may not be similarly associated with cardiac risk in women as it is in men.

One problem with the study was that the patients were all older, many had heart risk factors known as metabolic syndrome, and many were physically inactive, all of which are risk factors for heart disease. Given this limitation, the new research may not impact on how patients are treated. Also, the study didn't look at men under the age of 60 years though they  did note that people are now getting diagnosed with type 2 diabetes at an earlier  age, thus  indicating more people who are in need of more aggressive treatment. The findings may help to stratify patients based on risk level, to better determine who needs what type of care and when.