Insulin pump treatment vs. multiple daily insulin injections in patients with poorly controlled type 2 diabetes mellitus: a comparison of cardiovascular effects

Abstract

Abstract Background Both hyper- and hypo-glycaemia, as well as large glycaemic variability (GV) are associated with increased cardiovascular events in patients with type 2 diabetes mellitus (T2DM); possible contributing mechanisms of the increased cardiovascular risk include endothelial dysfunction and cardiac sympatho-vagal imbalance. Recent studies suggest that continuous subcutaneous insulin infusion (CSII) improves glycaemic control compared to multiple daily insulin injections (MDI). Purpose In this study, we assessed whether CSII may improve cardiac autonomic and vascular dilation function compared to MDI. Methods We enrolled in a small randomized pilot study consecutive T2DM patients without cardiovascular disease with poor glycaemic control, despite optimized MDI therapy. Patients were randomized to CSII (Group 1) or to continue MDI (Group 2); insulin dose was adjusted to achieve optimal glycaemic target ranges. Patients were studied at baseline and after 6 months by: 1) assessment of flow-mediated dilation (FMD) and nitrate-mediated dilation (NMD) of the brachial artery; 2) heart rate variability (HRV) by 24-hour ECG Holter monitoring; 3) a 7-day continuous glucose monitoring (CGM) was performed at baseline and follow-up in 8 and 7 patients of Group 1 and 2, respectively. Results Overall, 21 patients were enrolled, 12 randomized to CSII and 9 to MDI. Daily insulin dose, glycated hemoglobin levels and CGM parameters did not differ significantly between the 2 groups, both at baseline and at follow-up. Both FMD (6.7±2.5 vs 4.6±2.0 %, p=0.51) and NMD (8.9±3.1 vs 7.0±3.0 %, p=0.18), as well as HRV parameters, showed no significant differences between the 2 groups at 6-month follow-up. No relation between GV and both peripheral dilator function and cardiac autonomic function was also detected. Conclusions In this small, randomized pilot study we show that, in T2DM patients, CSII achieves similar medium-term glycaemic control compared to MDI, without any significant adverse effect on the cardiovascular system.