Original investigation

Improved glycaemic control by switching from insulin NPH to insulin glargine: a retrospective observational study

Peter Sharplin¹ , Jason Gordon¹ , John R Peters² , Anthony P Tetlow¹ , Andrea J Longman¹ and Philip McEwan¹

¹  CHKS Health Economics Unit, Health Park, Cardiff, UK

²  Department of Medicine, School of Medicine, Cardiff University, Cardiff, UK

author email corresponding author email

Cardiovascular Diabetology 2009, 8:3doi:10.1186/1475-2840-8-3

Published:	19 January 2009

Abstract

Background

Insulin glargine (glargine) and insulin NPH (NPH) are two basal insulin treatments. This study investigated the effect on glycaemic control of switching from a NPH-based regimen to a glargine-based regimen in 701 patients with type 1 (n= 304) or type 2 (n= 397) diabetes, using unselected primary care data.

Methods

Data for this retrospective observational study were extracted from a UK primary care database (The Health Improvement Network). Patients were required to have at least 12 months of data before and after switching from NPH to glargine. The principal analysis was the change in HbA_1c after 12 months treatment with glargine; secondary analyses included change in weight and total daily insulin dose. Inconsistent reporting of hypoglycemic episodes precludes reliable reporting of this outcome. Multivariate analyses were used to adjust for baseline characteristics and confounding variables.

Results

After adjustment, both diabetic cohorts showed statistically significant reductions in mean HbA_1c 12 months after the switch, by 0.38% (p < 0.001) in type 1 patients and 0.31% (p < 0.001) in type 2 patients. Improvement in HbA_1c was positively correlated with baseline HbA_1c; patients with baseline HbA_1c ≥ 8% had reductions of 0.57% (p < 0.001) and 0.47% (p < 0.001), respectively. There was no significant change in weight or total daily insulin dose while on glargine. The majority of patients received a basal-bolus regimen prior to and after the switch (mean 79.3% before and 77.2% after switch in type 1 patients, and 80.4% and 76.8%, respectively in type 2 patients, p > 0.05).

Conclusion

In routine clinical practice, switching from NPH to glargine provides the opportunity for improving glycaemic control in diabetes patients inadequately controlled by NPH.