A large Scandinavian study has shown that insulin from an insulin pump is associated with much lower risks of cardiovascular deaths, as well as deaths from other causes, compared with use of insulin pens. Lead study author Dr. Isabelle Steineck from Aarhus University Hospital in Denmark and her team looked at 18,168 patients with type 1 diabetes in the Swedish National Diabetes Register.

Of these, 15,727 controlled their diabetes with multiple daily injections of insulin, while the other 2,441 patients used insulin pumps. The group was followed for almost 7 years, until December 2012. The study team analysed the rates of fatal coronary heart disease, fatal cardiovascular disease (coronary heart disease or stroke) and death from all causes. With multiple daily injections as reference, the adjusted hazard ratios for insulin pump treatment were significantly lower. Using an insulin pump was associated with a 45% reduction in risk of fatal coronary heart disease compared to using injected insulin, a 42% risk reduction for fatal cardiovascular disease and a 27% lower risk of dying from any cause.

There were some differences between the two groups, the researchers note. Patients who used insulin pumps tended to be somewhat younger, had lower blood pressure and less heart disease, were more active, smoked less and were better educated. Another mechanism worth consideration is that treatment with insulin pump might lead to a lower frequency and duration of hyperglycaemia, corresponding to reduced long term occurrence of microvascular and cardiovascular complications.

There is a rationale for insulin pump treatment resulting in more stable blood glucose concentrations than multiple daily injections. Hypoglycaemia is a risk factor for cardiovascular events, particularly among high risk individuals. A retrospective analysis of a large cohort of people with type 1 diabetes treated with insulin pump therapy, however, pointed to a higher prevalence of cardiovascular disease in those with a history of repeated hypoglycaemic episodes.

The authors did a second analysis that only included the 16,427 patients without any history of cardiovascular disease, heart failure or a type of abnormal heart rhythm called atrial fibrillation, the results were similar to those of the whole group.

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