One potato, two potato,… assessing carbohydrate counting accuracy in adolescents with type 1 diabetes

Carbohydrate (CHO) counting is a recommended daily practice to help manage blood glucose levels in type 1 diabetes. Evidence suggests that CHO estimates should be within 10 to 15 g of the actual meal for optimal postprandial blood glucose control. The objective of this study was to assess accuracy of CHO counting in adolescents with type 1 diabetes.

Adolescents (aged 12-18 years) with type 1 diabetes who self-identified as regular CHO counters were recruited from the SickKids Diabetes Clinic, Toronto, Canada. Adolescents completed the PedsCarbQuiz (PCQ) and estimated CHO content of test trays (three meals and three snack trays) that were randomly assigned. Analyses were conducted to identify factors associated with accuracy of counting and CHO counting knowledge (PCQ score).

A total of 140 adolescents (78 females, mean age 14.7, SD = 1.8) participated. The average PCQ score was 81 ± 10%. Forty-two percent of adolescents were accurate in estimating meal trays (ie, within 10 g of the actual CHO content), 44% estimated inaccurately (within 10-20 g), while 14% were significantly inaccurate counters (>20 g variation). PCQ scores were higher in teens who CHO counted accurately than in those with significant inaccuracy (>20 g) (P < 0.05), and a longer duration of diabetes corresponded significantly with a lower PCQ score. No demographics correlated significantly with CHO counting accuracy.

Less than half of the teens in our study were accurate CHO counters. These results indicate the need for regular clinical accuracy check and reeducation.