A large Swedish study has demonstrated that people with type 1 diabetes who use continuous subcutaneous insulin infusion (CSII) therapy have almost a 50% reduction in risk of cardiovascular disease (CVD) compared with those who use multiple daily insulin injections (MDI).
In this observational study of the Swedish National Diabetes Register, the investigators evaluated 18 168 people with type 1 diabetes (mean age, 40 years), of whom 2441 were using insulin pump therapy and 15 727 were using MDI. Over a mean follow-up of 6.8 years (114 135 person-years), 83 people in the CSII group (3.4%) died, compared with 1109 (7.1%) in the MDI group (adjusted hazard ratio [HR], 0.73). HRs for fatal coronary heart disease (CHD) and fatal CVD (CHD or stroke) were 0.55 and 0.58, respectively. Mean HbA1c did not differ between the groups either at baseline or at the final follow-up. The proportion of people who had three or more hypoglycaemic events was significantly lower in the CSII group (0.2% vs. 0.6%; P=0.034).
The authors propose two potential mechanisms to account for these findings: first, the lower rate of multiple hypoglycaemic incidents, which are associated with a higher risk of CV events, and secondly the potential lower frequency and duration of hyperglycaemia, although HbA1c did not significantly differ between the groups. However, they also state that the retrospective design of the study precludes firm conclusions as to whether the CSII treatment was directly responsible for the reduced risk. They point out that the findings could also be attributable to intensified glucose monitoring, increased motivation to control blood glucose levels or a better knowledge about type 1 diabetes.
The study can be read in the BMJ here.
