Effects of carbohydrate counting on glucose control and quality of life over 24 weeks in adult patients with type 1 diabetes on continuous subcutaneous insulin infusion: a randomized, prospective clinical trial (GIOCAR)

OBJECTIVE

Few studies have assessed the efficacy of carbohydrate counting in type 1 diabetes, and none have validated its efficacy in patients who are treated with continuous subcutaneous insulin infusion (CSII). The aim of our study was to test the effect of carbohydrate counting on glycemic control and quality of life in adult patients with type 1 diabetes who are receiving CSII.

RESEARCH DESIGN AND METHODS

Sixty-one adult patients with type 1 diabetes treated with CSII were randomly assigned to either learning carbohydrate counting (intervention) or estimating pre-meal insulin dose in the usual empirical way (control). At baseline and 12 and 24 weeks, we measured HbA_1c, fasting plasma glucose, BMI, waist circumference, recorded daily insulin dose, and capillary glucose data, and administered the Diabetes-Specific Quality-of-Life Scale (DSQOLS) questionnaire.

RESULTS

Intention-to-treat analysis showed improvement of the DSQOLS score related to diet restrictions (week 24 – baseline difference, P = 0.008) and reduction of BMI (P = 0.003) and waist circumference (P = 0.002) in the intervention group compared with control subjects. No changes in HbA_1c, fasting plasma glucose, daily insulin dose, and hypoglycemic episodes (<2.8 mmol/L) were observed. Per-protocol analysis, including only patients who continuously used carbohydrate counting and CSII during the study, confirmed improvement of the DSQOLS score and reduction of BMI and waist circumference, and showed a significant reduction of HbA_1c (−0.35% vs. control subjects, P = 0.05).

CONCLUSIONS

Among adult patients with type 1 diabetes treated with CSII, carbohydrate counting is safe and improves quality of life, reduces BMI and waist circumference, and, in per-protocol analysis, reduces HbA_1c.Nutritional management is a cornerstone in the management of diabetes, and monitoring of carbohydrate intake, a major determinant of postprandial blood glucose, is a key strategy for achieving good glucose control (1–4).Some studies have examined the contribution of quantity and type (i.e., simple vs. complex) of carbohydrates in patients with type 1 diabetes and showed that the daily insulin requirement is indeed associated with the amount rather than the type of daily carbohydrate intake (4–6).Over the years, a number of methods have been proposed to help patients with diabetes to quantify the carbohydrate content of a meal in real life, for example, exchange lists, portion/servings, grams, glycemic index, and insulin:carbohydrate ratio (I:CHO) (7–9). Among these, the I:CHO is considered the most advanced counting technique, consisting of estimating the grams of carbohydrates in a meal and then calculating the pre-meal insulin dose based on this estimation and an insulin sensitivity measure (8). Carbohydrate counting was devised in the 1960s, but it has become widely used as part of intensive diabetes management after the Diabetes Control and Complications Trial (DCCT) (10,11).Although carbohydrate counting is widely used by patients worldwide, few studies have validated its efficacy in type 1 diabetes (12,13), and none have validated its efficacy in adult patients receiving continuous subcutaneous insulin infusion (CSII). We designed the current study with the aim of testing the effect of carbohydrate counting on glucose control and quality of life over 24 weeks in adult patients with type 1 diabetes treated with CSII.