Glycaemic control with continuous subcutaneous insulin infusion compared with intensive insulin injections in patients with type 1 diabetes: meta-analysis of randomised controlled trials

Abstract

Objective: To compare glycaemic control and insulin dosage in people with type 1 diabetes treated by continuous subcutaneous insulin infusion (insulin infusion pump therapy) or optimised insulin injections. Design: Meta-analysis of 12 randomised controlled trials. Participants: 301 people with type 1 diabetes allocated to insulin infusion and 299 allocated to insulin injections for between 2.5 and 24 months. Main outcome measures: Glycaemic control measured by mean blood glucose concentration and percentage of glycated haemoglobin. Total daily insulin dose. Results: Mean blood glucose concentration was lower in people receiving continuous subcutaneous insulin infusion compared with those receiving insulin injections (standardised mean difference 0.56, 95% confidence interval 0.35 to 0.77), equivalent to a difference of 1.0 mmol/l. The percentage of glycated haemoglobin was also lower in people receiving insulin infusion (0.44, 0.20 to 0.69), equivalent to a difference of 0.51%. Blood glucose concentrations were less variable during insulin infusion. This improved control during insulin infusion was achieved with an average reduction of 14% in insulin dose (difference in total daily insulin dose 0.58, 0.34 to 0.83), equivalent to 7.58 units/day. Conclusions: Glycaemic control is better during continuous subcutaneous insulin infusion compared with optimised injection therapy, and less insulin is needed to achieve this level of strict control. The difference in control between the two methods is small but should reduce the risk of microvascular complications. What is already known on this topic: Continuous subcutaneous insulin infusion (insulin pump therapy) produces good long term control of blood glucose concentrations in people with type 1 diabetes Control of blood glucose concentration is substantially better on pump therapy than conventional (non-optimised) injection therapy It is unclear how glycaemic control on pump therapy compares with modern optimised insulin injection regimens What this study adds: Though glycaemic control was better during continuous subcutaneous insulin infusion than optimised insulin injection therapy, the difference was relatively small Continuous subcutaneous insulin infusion is an effective form of intensive insulin therapy that should lower the risk of microvascular complications Insulin pump therapy is unnecessary for most people with type 1 diabetes and should be reserved for those with special problems with optimised insulin injections