Improvement of β‐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 β-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 ≥ 1 year before CSII therapy, and duration of CSII therapy ≥ 6 months. 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 10 years; interquartile range (IQR) 6.0–17.0; CSII therapy ≤30 months], median HbA1c decreased from 8.7% (IQR 7.7–10.0) at baseline to 6.3% (IQR 5.9–6.9) after 6 months of CSII therapy (p < 0.0001). During the subsequent 24 months, median HbA1c levels were maintained between 6.3% and 6.5% (p < 0.0001 for all time points vs baseline). At 12 months after CSII therapy, median C-peptide levels began to increase compared with baseline (fasting level 23% increase, p < 0.0001; 2-h postprandial level 26% increase, p = 0.022), and the increase was maintained at 30 months (fasting level 39%; 2-h postprandial level 53%; p < 0.0001 for all vs baseline). Conclusions β-Cell function was significantly improved in patients with non-newly diagnosed and suboptimally controlled type 2 diabetes after achieving and maintaining optimal glycaemic control with long-term CSII therapy alone. Copyright © 2013 John Wiley & Sons, Ltd.