Insulin pump users had lower cardiovascular mortality than similar patients with type 1 diabetes who injected their own insulin, a study found.
The observational study used data from the Swedish National Diabetes Register to follow 2,441 type 1 diabetes patients who used insulin pumps and 15,727 who used multiple daily insulin injections for a mean of 6.8 years ending in December 2012. Results were published by The BMJ on June 22.
Compared to the injection patients, the pump group had a significantly lower risk of fatal coronary heart disease (adjusted hazard ratio [HR], 0.55; 95% CI, 0.36 to 0.83), fatal cardiovascular disease (adjusted HR, 0.58; 95% CI, 0.40 to 0.85), and all-cause mortality (adjusted HR, 0.73; 95% CI, 0.58 to 0.92). Unadjusted, the pump group had 3 fewer cases of fatal coronary heart disease per 1,000 person-years, with corresponding figures of 3.3 and 5.7 for fatal cardiovascular disease and all-cause mortality, respectively. The mean HbA1c did not differ significantly between the 2 groups.
The study was limited by its observational nature, the researchers said; however, they calculated that at least 80% of the injection group would have had to have an unmeasured confounder to negate the study results. However, pump group patients would have received additional training regarding their disease and pump use, so some of the observed effects might result from intensified monitoring, increased motivation, or greater knowledge among pump users, the authors said.
The benefit of insulin pumps could also be explained by fewer severe hypoglycemic episodes occurring during pump use or by lower frequency and duration of hyperglycemia on the pump, the study authors speculated. The study authors concluded, “Whether the results reflect the physiological consequences of insulin pump treatment, the clinical management that pump users receive, or the educational aspects of having the pump remains elusive.”