Diabetic patients often suffer from muscle cramps. This study aimed to compare the quality of life (QOL) of diabetic patients with and without muscle cramps and to investigate the effect of L-carnitine supplementation in diabetic patients with muscle cramps. A total of 91 patients with diabetes were enrolled in this study: 69 patients with muscle cramps and 22 patients without muscle cramps. Muscle cramps and QOL were evaluated using the muscle cramp questionnaire and the Short Form 36 health survey version 2 (SF-36), respectively. Clinical characteristics were compared between diabetic patients with and without muscle cramps. In the prospective portion of the study, 25 diabetic patients with muscle cramps received L-carnitine supplementation (600 mg/day orally) for 4 months. The questionnaires were administered before and after supplementation. The SF-36 scores in diabetic patients with muscle cramps were lower than those in patients without muscle cramps on the subscales of physical function, role physical, bodily pain, vitality, general health, and social function. In the 25 patients with muscle cramps who received L-carnitine supplementation, the monthly frequency of muscle cramps and Wong-Baker FACES® Pain Rating Scale scores were significantly decreased. Scores on the following SF-36 subscales improved after L-carnitine supplementation: body pain, vitality, social function, and role emotional. This study demonstrated that muscle cramps decrease the QOL in patients with diabetes, and L-carnitine supplementation may improve the QOL by reducing the frequency and severity of muscle cramps in these patients.
Keywords: Diabetes mellitus; Levocarnitine; Muscle cramp; Quality of life.