Effect of 4 years subcutaneous insulin infusion treatment on albuminuria, kidney function and HbA_1c compared with multiple daily injections: A longitudinal follow-up study

Aim: The effect of insulin pump [continuous subcutaneous insulin infusion (CSII)] treatment on diabetes complications in a modern clinical setting is largely unknown. We investigated the effect of 4 years CSII treatment on HbA_1c, albuminuria and kidney function compared with multiple daily injections (MDI) in a single-centre clinical setting. Methods: All patients initiating CSII treatment from 2004 to 2010 and followed for at least 4 years were included in the study: 193 people with Type 1 diabetes were matched (1:2) with 386 patients treated with MDI in the same period. Matching was based on diabetes duration, gender, HbA_1c and normo-, micro- or macroalbuminuria at baseline. Urinary albumin/creatinine ratio (UACR) was measured yearly and annual change assessed from linear regression. Results: CSII- vs. MDI-treated patients were comparable at baseline. After 4 years, HbA_1c was 62 ± 11 vs. 68 ± 11 mmol/mol (7.8 ± 1.0 vs. 8.4 ± 1.0%) (P < 0.001). Annual UACR change in CSII- vs. MDI-treated patients was [mean (95% confidence interval)] -10.1 (-13.3; -6.8) vs. -1.2 (-3.6; 0.9)% (P < 0.001). Reduction in UACR was significantly associated with CSII treatment after adjustment for age, gender, diabetes duration, estimated GFR, UACR, mean arterial pressure, HbA_1c, cholesterol, renin-angiotensin-aldosterone system inhibition, anti-hypertensive treatment and smoking (P < 0.001). This remained significant (P < 0.001) when only including patients on stable renin-angiotensin-aldosterone system inhibition during follow-up (n = 465). Conclusions: Treatment with CSII over 4 years independently reduced HbA_1c and UACR compared with MDI. Reduced UACR may be due to less glycaemic variability because the effect of CSII on HbA_1c could only partially explain the effect. This needs confirmation in randomized controlled trials.