Carbohydrate (CHO) counting enables people with Type 1 diabetes to adjust mealtime insulin dose to carbohydrate intake. In clinical practice, a number of methods for CHO quantification are commonly used, including 1-g increments, 10-g portions and 15-g exchanges. However, there has been a lack of evidence to determine whether one method of teaching CHO counting is superior to another. Additionally, increasing clinical evidence suggests the impact of other macronutrients should be considered in insulin dosing.
We conducted a sequence of studies to determine the precision required in CHO counting to maintain postprandial glycaemia. The studies demonstrated that a 15% error in carbohydrate quantification for a meal does not make a difference to postprandial glucose levels, but that a 30% variation results in postprandial hypoglycaemia and hyperglycaemia. This suggests that a mealtime insulin dose covers a range in carbohydrate quantity; however accuracy to within ± 10 grams of the meal carbohydrate content is necessary.
The ability of people with diabetes to accurately count CHO is an important clinical issue. A questionnaire conducted in clinics in Australia and the UK examined how precisely children and their parents could count CHO. The results showed that 73% of estimates were within a 10-15 gram error margin, no matter which method of CHO counting was used. The findings demonstrate that children and their parents can accurately quantify CHO, provided education is given by experienced health professionals.
There is increasing evidence that the impact of other macronutrients should be considered when determining the bolus insulin dose and delivery. A recent study conducted at the John Hunter Children’s Hospital, NSW and Princess Margaret Children’s Hospital, WA examined the effects of high protein and high fat meals, all with the same carbohydrate content, on postprandial glycaemia. The results from this study, including practical strategies to manage meals high in fat and protein, will be outlined.