Effects of advanced carbohydrate counting in patients with type 1 diabetes: a systematic review

Advanced carbohydrate counting, a systematic method for insulin bolus calculation, is recommended in the management of type 1 diabetes. The aim of this systematic review was to summarize all available evidence from randomized and observational studies of the effects of advanced carbohydrate counting on glycaemic control (HbA(1c)), psychosocial measures, weight and hypoglycaemic events in patients of all age groups with type 1 diabetes on a basal-bolus insulin regimen.

An electronic search of Scopus, MEDLINE and The Cochrane Library conducted in January 2013 identified 27 relevant articles. Six were randomized controlled trials and 21 were observational studies. Large heterogeneity existed across studies with regard to study design and patient populations. Reporting of statistical measures was insufficient to serve as a basis for a meta-analysis.

Overall, the studies demonstrated a positive trend in change in HbA(1c) after introduction of advanced carbohydrate counting. Reductions in HbA(1c) ranged from 0.0 to 13 mmol/mol (0.0-1.2%). Most psychosocial measures improved; however, only few improvements were considered clinically relevant. Both weight gain and reduction were registered, but most studies found no significant weight changes. The majority of studies assessing the incidence of hypoglycaemic events found a significant reduction in the event rate and none reported an increase in the incidence.

In summary, the currently available literature does not provide sufficient evidence to definitively determine the effects of advanced carbohydrate counting on HbA(1c), psychosocial measures, weight or hypoglycaemic events. Nevertheless, the method still appears preferable to other insulin dosing procedures, which justifies continued use and inclusion of advanced carbohydrate counting in clinical guidelines.