Does diabetes have the same impact on cardiovascular risk in HIV-positive patients as it does in the general population?

The multicentre, multi-continent D:A:D study has contributed greatly to our increased understanding of risk factors for development of cardiovascular disease in HIV-infected individuals. Signe Worm from Copenhagen presented an analysis of just how much does a diagnosis of diabetes contribute to the risk of myocardial infarction.

Current NCEP guidelines consider a diagnosis of diabetes to be a coronary heart disease (CHD) risk equivalent, meaning that if you have diabetes you should be considered to be at the same risk for heart attack as someone already diagnosed with CHD, and thus lipid problems should be managed just as aggressively in diabetics.

Older data from the general population to justify this approach, but some more recent studies have not confirmed that the magnitude of risk from diabetes alone is as great – thus this question of diabetes being a CHD risk equivalent is somewhat controversial in the general population as well.

Published guidelines for managing lipid disorders in HIV-positive patients on ART have stated that the NCEP guidelines should be followed just as they are in the general population. However, it has not been documented in HIV-positive patients, that a diagnosis of diabetes carries the same CHD risk as it does in the general population. It is possible, because insulin resistance/impaired glucose tolerance may be present for decades before a diagnosis of diabetes is made in the general population, that there is cumulative risk incurred over a prolonged period even before overt diabetes is diagnosed.

With HIV infection, if insulin resistance/impaired glucose tolerance is caused by antiretroviral therapy and is present only for a much shorter period of time before over diabetes is diagnosed, or if diagnosis of diabetes is made much sooner because of increased health care visits and routine blood glucose monitoring, or is diagnosed at a much younger age, a current diagnosis of diabetes may have a much lesser impact on CHD risk.

The D:A:D data confirm that diabetes increases CHD risk, but a diagnosis of diabetes mellitus without known pre-existing CHD provided only about one third of the CHD event risk that a prior CHD diagnosis gave. This would suggest that perhaps, a diabetes diagnosis in an HIV-infected individual should not necessarily lead to lipid management that is as aggressive as in an HIV-infected individual with pre-existing CHD but no diabetes.

Alternatively, it could be argued that because HIV infection itself increases CHD risk, and because diabetes is discovered sooner, this early diabetes diagnosis would provide an excellent opportunity for preventative early lipid intervention in HIV-infected diabetics well before there is longer-term vascular damage from years of insulin resistance and impaired glucose tolerance. Importantly, the D:A:D results do not address the central question of, will the risks from following current NCEP guidelines for diabetics outweigh the benefits in those with HIV?

For now, it seems reasonable to continue to follow the NCEP guidelines until there are more data including external validation of the D:A:D results on other prospective cohorts.

Worm S et al. Does diabetes mellitus (DM) confer an equivalent risk of coronary heart disease (CHD) to pre-existing CHD in HIV-positive individuals?