People with diabetes have the same high risk for heart attack or stroke or cardiovascular death as people who've already had a heart attack, researchers reported in Circulation: Journal of the American Heart Association.
"The increased risk was observed in people at all ages with either type 1 or type 2 diabetes who were receiving insulin or other drugs to reduce levels of sugar in the blood," said Tina Ken Schramm, M.D., lead author of the study and research fellow at the Gentofte Hospital in Hellerup, Denmark. "When people with diabetes do have heart attacks, they are twice as likely to die as non-diabetics."
"We've talked about 'the lower, the better' for cholesterol and blood pressure to reduce the risk of heart attack," Schramm said. "Now I think we should be saying 'the sooner, the better' for primary prevention of cardiovascular diseases in diabetics."
In the population study of 3.3 million people age 30 and older living in Denmark in 1997, 71,801 people had diabetes and 79,575 had a previous heart attack. Researchers identified deaths over five years from a central population register and causes of death were obtained from a national register. They got diagnoses from a national patient registry and information on medication was obtained from registries on claimed prescriptions in the national pharmaceutical database. Due to the comprehensive national registries in Denmark and the possibility of cross-linkage of all registries, it was possible to study a totally unselected population including all patients with diabetes receiving glucose-lowering medication.
In Cox-proportional regression analyses the relative risk (hazard ratio) of dying from cardiovascular disease was 2.45 times greater for women with diabetes compared with 2.62 times greater for women with a prior heart attack. The relative risk of dying from cardiovascular causes in men with diabetes was 2.42 times higher compared with a 2.44 hazard ratio in men with prior heart attack.
For the composite of heart attack, stroke and death from cardiovascular disease, the hazard ratios in men with diabetes were 2.32 versus 2.48 for men who had at least one heart attack. For women with diabetes, the relative risk of the combined end point of heart attack, stroke or cardiovascular death was 2.48 and those with a history of myocardial infarction faced a hazard ratio of 2.71.
Researchers said "the major finding of this study is that all patients age 30 and older who require glucose-lowering treatment are at a particularly high risk of cardiovascular death and disease, comparable to that of non-diabetics with a prior heart attack, regardless of sex and diabetes type."
Schramm noted, however, that they were unable to study patients on diet-only treatment, which was a limitation of the study. Moreover, the researchers couldn't precisely differentiate between type 1 and type 2 diabetes patients and couldn't adjust for several well-known risk factors including high blood pressure, high cholesterol, obesity, smoking, physical activity and blood glucose levels.
Type 2 diabetes is the most common form of diabetes. It develops when the body doesn't make enough insulin and doesn't efficiently use the insulin it makes (insulin resistance). It appears most often in middle-aged adults, but adolescents and young adults are developing type 2 diabetes at an alarming rate.
In type 1 diabetes patients, the pancreas makes little or no insulin. Type 1 diabetes is usually first diagnosed in children and young adults. Without daily injections of insulin, people with type 1 diabetes won't survive. Both forms of diabetes may be inherited.
Based on the study results, Schramm suggested that all people with diabetes who are receiving glucose-lowering therapy should talk to their physicians about being started on daily aspirin therapy as well as treatment with cholesterol-lowering drugs known as statins and possibly blood pressure-lowering drugs called ACE-inhibitors. And those treatments, which are effective heart attack prevention strategies, should be also considered in the younger age groups of these diabetes patients.
Co-authors are: Gunnar H. Gislason M.D.; Lars Kober, M.D., D.M.Sc.; Soren Rasmussen, M.Sc., Ph.D.; Jeppe N. Rasmussen, M.D.; Steen Z. Abildstrom, M.D., Ph.D.; Morten Lock Hansen, M.D.; Fredik Folke, M.D.; Pernille Buch, M.D.; Mette Madsen, M.Sc.; Allan Vaag, M.D., D.M.Sc.; and Christian Torp-Pedersen, M.D., D.M.Sc.
The Danish Pharmacist Foundation funded the study.
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