IntroductionCarbohydrate counting (CC) is an important nutritional strategy to improve glycaemic outcomes among patients with diabetes. Few studies have investigated CC knowledge among individuals with type 1 diabetes mellitus (T1DM) in Saudi Arabia. Therefore, we aimed to evaluate CC knowledge in Saudi adults with T1DM.Study design and methodsA cross-sectional study was conducted between December 2021 and February 2022, including 224 patients with T1DM from the University Diabetes Center, Riyadh. Adults aged ≥18 years, diagnosed with T1DM for >1 year, and residing in Saudi Arabia were included. CC knowledge was assessed using a previously well-studied tool (AdultCarbQuiz), which was translated into Arabic and tested for validity by a group of dieticians. Descriptive statistics were used for data analysis, and bivariate and regression analyses were conducted.ResultsThe AdultCarbQuiz questionnaire-Arabic version had good validity and reliability (Cronbach’s α: 0.87). The CC method was used by 54% of the participants. The mean CC knowledge score was 23.01±7.31. A significant negative linear relationship between the participants’ CC knowledge scores, and age and glycated haemoglobin (HbA1c) levels, was revealed by simple regression analysis. Furthermore, significant independent variables related to CC knowledge scores were CC use, HbA1c levels, being taught about CC (>5 times), insulin pump usage and DM duration (≤15 years).ConclusionsApproximately half of the patients used the CC method. The mean CC knowledge scores were better in patients who used the CC method, were more frequently taught about CC, were treated using an insulin pump, and had a shorter DM duration than their counterparts. Therefore, designing and implementing a well-structured nutrition education programme tailored to individuals with diabetes is crucial to provide them with up-to-date dietary information, as well as the necessary knowledge and skills, to improve their outcomes and manage their condition.