AimsThis study aimed to investigate the effect of carbohydrate counting (carbC), with or without an automated bolus calculator (ABC), in children with type 1 diabetes treated with multiple daily insulin injections. MethodsWe evaluated 85 children, aged 9–16 years, with type 1 diabetes, divided into four groups: controls (n=23), experienced carbC (n=19), experienced carbC+ABC (n=18) and non-experienced carbC+ABC (n=25). Glycated haemoglobin (HbA1c), insulin use, and glycaemic variability – evaluated as high blood glucose index (HBGI) and low blood glucose index (LBGI) – were assessed at baseline and after 6 and 18 months. ResultsAt baseline, age, disease duration, BMI, HbA1c, insulin use, and HBGI (but not LBGI; p=0.020) were similar for all groups. After 6 months, HbA1c improved from baseline, although not significantly – patients using ABC (according to manufacturer's recommendations) HbA1c 7.14±0.41% at 6 months vs. 7.35±0.53% at baseline, (p=0.136) or without carbC experience HbA1c 7.61±0.62% vs. 7.95±0.99% (p=0.063). Patients using ABC had a better HBGI (p=0.001) and a slightly worse LBGI (p=0.010) than those not using ABC. ABC settings were then personalised. At 18 months, further improvements in HbA1c were seen in children using the ABC, especially in the non-experienced carbC group (−0.42% from baseline; p=0.018). ConclusionsCarbC helped to improve glycaemic control in children with type 1 diabetes using multiple daily injections. ABC use led to greater improvements in HbA1c, HBGI and LBGI compared with patients using only carbC, regardless of experience with carbC.