Improvement of [beta]-cell function after achievement of optimal glycaemic control via long-term continuous subcutaneous insulin infusion therapy in non-newly diagnosed type 2 diabetic patients with suboptimal glycaemic control

Background Achieving euglycaemia by continuous subcutaneous insulin infusion (CSII) therapy alone has been shown to restore [beta]-cell function in patients with newly diagnosed type 2 diabetes. However, the efficacy has not been evaluated in patients with non-newly diagnosed type 2 diabetes and suboptimal glycaemic control. Methods Of the 1220 patients with type 2 diabetes who began CSII therapy from March 2000 to March 2007, we retrospectively selected patients using the following inclusion criteria: glycosylated haemoglobin (HbA1c)≥7.0%, diabetes duration≥1year before CSII therapy, and duration of CSII therapy≥6months. We evaluated sequential changes in HbA1c and serum C-peptide levels measured at a 6- to 12-month intervals during CSII therapy. Results In the 521 subjects included in this study [median diabetes duration 10years; interquartile range (IQR) 6.0-17.0; CSII therapy ≤30months], median HbA1c decreased from 8.7% (IQR 7.7-10.0) at baseline to 6.3% (IQR 5.9-6.9) after 6months of CSII therapy (p