Impact of oral anti-hyperglycaemic therapy on all-cause mortality in diabetics

Impact of oral anti-hyperglycaemic therapy on all-cause mortality in diabetics

The authors of this retrospective study note that several observational studies have produced conflicting results on the effect of different classes of oral anti-hyperglycaemics on all-cause mortality. It has also been difficult to draw conclusions due to ‘confounding by indication’, whereby patients with more severe disease are exposed to more aggressive therapy and are more likely to suffer from an adverse outcome.

In the present study, researchers studied data from a cohort of patients with diabetes from the Veterans Health Administration (VHA). They sought to evaluate the impact of several classes of oral anti-hyperglycaemics relative to sulfonylurea monotherapy on overall mortality, adjusting for a number of confounding factors in an attempt to limit any confounding by indication.

All users of oral anti-hyperglycaemic therapy were identified (n=39,721) and classified into the following cohorts

• sulfonylurea monotherapy (S)
• metformin monotherapy (M)
• metformin + sulfonylurea (MS)
• TZD use alone or in combination with other oral agents (TZD; all users were pooled together as there were few deaths in the various sub-groups)
• no drug therapy

The authors found no difference between all-cause mortality between the S cohort and any of the other treatment cohorts. The adjusted odds ratios (each group compared to S) were 0.87 (95% CI 0.68- 1.10) for M, 0.92 (0.82-1.05) for MS, and 1.04 (0.75-1.46) for TZD.

The authors note that the duration of retrospective data was a limitation of the study, and suggest that ‘future work should assess whether long-term exposure to oral anti-hyperglycaemic medications have the potential to reduce all-cause or cause-specific mortality.’