Carbohydrate counting: How accurate should it be to achieve glycemic control in patients on intensive insulin regimens?

Abstract

Carbohydrate counting is an important meal-planning tool for patients on intensive insulin regimens. Preprandial insulin bolus is adjusted taking into account the carbohydrate content of each meal and the insulin-to-carb ratio of each patient throughout the day. Evidence suggests that accurate carbohydrate counting may have positive effects not only on reducing glycosylated hemoglobin concentration but also on decreasing the incidence of hypoglycemic episodes. Nevertheless, despite its benefits, the efficacy of carbohydrate counting depends on the ability of each patient, or its caregiver, to accurately estimate the carbohydrate content of each meal. Therefore, it is of great importance to understand how accurate should carbohydrate counting be, and the impact of inaccurate carbohydrate counting on the glycemic control of each patient. Within this work, we propose an analytic method that uses the insulin-to-carb ratio and the insulin sensitivity factor, along with the glycemic targets of each patient to calculate the limits of accurate carbohydrate counting, in order to achieve better glycemic control and to reduce hypoglycemic episodes.

Assessing the impact of inaccurate insulin-to-carbohydrate ratio on the patient's glycemic targets and lifestyle management

“…In this context, we proposed an analytic method that uses patient-specific data to compute the safe maximum interval for the error of the insulin-to-carbohydrate ratio estimations. Moreover, our method could be used to quantify the impact of lifestyle changes on patient health, 1 By AIM system, we can consider that the insulin-to-carbohydrate ratio does not change when the bodyweight changes, because the Total Daily Dose (T DD) insulin is linearly dependent of bodyweight. In AIM system is considered that T DD = k 1 • W, where k 1 is a nonzero positive constant.…”

“…Under these circumstances, the proposed method suggests that patients may experience some benefits if they have a bodyweight gain 1 . Nevertheless, it's important to bear in mind that diet to increase bodyweight must not increment the carbohydrates intake per meal.…”

“…While the basal insulin dosage is periodically adjusted in collaboration with the healthcare team, the bolus insulin doses are estimated by each patient before each meal. To be effective, the bolus insulin dose must be accurate, and its accuracy depends on several factors, namely, the patient ability to estimate the carbohydrate content of each meal [1,2], the Insulin-to-Carbohydrate Ratio (ICR), the Insulin Sensitivity Factor (IS F), the preprandial blood glucose [3], and the insulin remaining active from the last bolus [4]. Regarding the ICR and IS F factors, they are dynamic and correlated [5][6][7].…”

Impact of Carbohydrate Counting Error on Glycemic Control in Open-Loop Management of Type 1 Diabetes: Quantitative Assessment Through an In Silico Trial

“…Some studies attempted to quantify the impact of carbcounting error on T1D patients glycemic control, showing that CHO underestimation can cause postprandial hyperglycemia, while CHO overestimation can lead to hypoglycemic episodes. [16][17][18][19][20] Moreover, Smart et al 21 found that an error of ±10g per meal or snack on a meal size of 60g did not significantly deteriorate the postprandial control, while a ±20g error had a significant impact on postprandial glycemia. 22 Although errors in carb-counting can be mitigated by the adoption of closed-loop insulin delivery systems, 23 these systems are still used by only a fraction of people with T1D.…”

An adaptive bolus calculator to minimize the impact of inaccurate insulin to carbohydrate ratio

“…However, to be effective, the bolus insulin dose must be accurate. Although, to correctly calculating it is not simple since it depends on several factors, i.e., the carbohydrate intake at each meal (CHO) [2,3], the Insulin to Carbohydrate Ratio (ICR), the Insulin Sensitivity Factor (IS F), the preprandial blood glucose [4], the postprandial blood glucose target and the insulin remaining active from the last boluses. Concerning the ICR and IS F factors, they are correlated and dynamic [5][6][7], changing along the day due to several factors, namely, physical activity, stress, health condition, or the hormone cycle, making it hard to get [8].…”