This retrospective study used national data from the Veterans Health Administration, Medicare, and National Death Index, to compare the risk of a composite outcome of acute myocardial infarction, stroke, or death in veterans with type 2 diabetes in whom metformin did not control their condition and who added either a sulfonylurea or insulin to their treatment regimen.
A related editorial comments that the study findings do not distinguish between exogenous insulin or the degree of insulin resistance. Furthermore, it is not known if additional potential unmeasured confounders could have influenced these results such as the aggressiveness of disease progression; the duration of diabetes; and the long-term history of other medications patients have tried. Given these limitations to the data, there are unlikely to be any changes to current practice.
The author also illustrates the complexities of interpreting observational comparative effectiveness studies, the design of which the current study is based. Although this type of research generates new evidence, the barriers to interpretation make it more difficult to apply results to clinical practice.