Assessment of the effectiveness of long-term insulin pump therapy using a combined goal of HbA1c decrease and absence of severe hypoglycemia

Abstract

ObjectiveLess than one third of patients with type 1 diabetes mellitus (T1DM) achieve the cut-off value proposed as good metabolic control by most guidelines, HbA1c <7 %. However, HbA1c reductions and prevention of severe hypoglycemia (SH) have shown clinically relevant benefits. The study objective therefore was to assess the effectiveness of continuous subcutaneous insulin infusion (CSII) therapy at 5 years of follow-up in a cohort of patients attending a specialized unit using HbA1c reduction and SH absence as combined goals. MethodsA retrospective, observational study on 178 patients with T1DM who started CSII treatment at Hospital Clinic of Barcelona between 2003 and 2008. HbA1c levels at baseline and after 5 years of treatment with CSII and presence or absence of SH were recorded. The combined variables calculated included: a) HbA1c reduction by ≥0.5 points and absence of SH in the last 2 years; b) HbA1c at 5 years <7.5 % and no SH in the last 2 years; c) HbA1c <8.5 % and no HG in the last 2 years; d) HbA1c reduction by ≥0.5 points and/or HbA1c <7.5 % at 5 years with no SH in the last 2 years of follow-up. ResultsTwenty-seven of the 178 patients were excluded due to loss to follow-up or CSII discontinuation. A total of 151 patients (aged 37.4 ± 10.5 years, 64 % women, diabetes duration of 19.2 ± 10.7 years) were therefore analyzed. The two main reasons for starting CSII were suboptimal metabolic control (SMC, 60.9 %) and severe hypoglycemia/hypoglycemia unawareness (25.5 %). HbA1c levels in total cohort and in patients with SMC were 8.0 ± 1.2 and 8.4 ± 1.1 at CSII start and 7.8 ± 1.2 and 8.0 ± 1.3 at 5 years of treatment (p = 0.104 and p = 0.016) respectively. In the overall cohort, 55.5 % of patients achieved at 5 years the combined goal of HbA1c <7.5 % and/or HbA1c reductions ≥ 0.5 % without SH. ConclusionsAfter 5 years of CSII therapy, more than half the patients achieved the combined goal of significant HbA1c reduction and absence of SH. Use of combined goals offers the opportunity to assess the effectiveness of T1DM treatment from a viewpoint closer to its clinical meaning.