Intermittently Scanned Continuous Glucose Monitoring and Automated Bolus Calculation in Type 1 Diabetes Treated with Multiple Daily Insulin Injections: A Randomized Controlled Trial

In a randomized controlled multicenter trial, 170 adults with type 1 diabetes ≥1 year, multiple daily insulin injections, HbA1c >7.0% (53 mmol/mol), were randomized to usual care (n=42), carbohydrate counting with automated bolus calculation (ABC) (n=41), intermittently scanned continuous glucose monitoring (isCGM) (n=48), or ABC+isCGM (n=39). HbA1c, blinded CGM and patient-reported outcomes were recorded at baseline and after 26 weeks. Primary outcome was change in time in range (TIR) with isCGM vs. usual care. Baseline characteristics were comparable across intervention arms; median (Q1;Q3) diabetes duration 18 (10;28) years, HbA1c 8.1 (7.7;8.7) % (65 (61;72) mmol/mol) and mean (SD) BMI 26.7 (3.9) kg/m2. Changes in TIR, hypo- and hyperglycemia were similar in the intervention arms compared to usual care. Daytime TIR increased 22 (95% CI: 1;47) % with ABC and nighttime hyperglycemia increased 258 (40;814) % with isCGM compared to usual care. With ABC+isCGM, HbA1c was reduced 0.4 (0.1;0.7) % (4 (1;8) mmol/mol) and glucose coefficient of variation (CV) was reduced 11 (4;17) % compared to usual care. Treatment satisfaction improved with isCGM and ABC+isCGM. With ABC+isCGM, empowerment and present life quality also improved. Within the ABC and isCGM arms, we observed HbA1c reductions of 0.3 and 0.3% (4 and 3 mmol/mol), respectively, however not significantly different from usual care. Statistical significance was maintained after adjustment for multiple testing with regards to CV and treatment satisfaction with ABC+isCGM, and treatment satisfaction with isCGM only.

In conclusion, although no significant improvement in TIR was achieved, simultaneous intervention with ABC+isCGM improved the coefficient of variation and treatment satisfaction compared to usual care, and HbA1c was clinically relevant reduced, in adult technology-naïve persons with type 1 diabetes and suboptimal HbA1c.