Creatine supplementation may have a therapeutic role in diabetes, but it is uncertain whether this supplement is safe for kidney function. The aim of this study was to investigate the effects of creatine supplementation on kidney function in type 2 diabetic patients. A randomized, double-blind, placebo-controlled trial was performed. The patients were randomly allocated to receive either creatine or placebo for 12 weeks. All the patients underwent exercise training throughout the trial. Subjects were assessed at baseline and after the intervention. Blood samples and 24-h urine samples were obtained for kidney function assessments. Additionally, 51 Cr-EDTA clearance was performed. To ensure the compliance with creatine intake, we also assessed muscle phosphorylcreatine content. The creatine group presented higher muscle phosphorylcreatine content when compared to placebo group (CR Pre 44 ± 10, Post 70 ± 18 mmol/kg/wt; PL Pre 52 ± 13, Post 46 ± 13 mmol/kg/wt; p = 0.03; estimated difference between means 23.6; 95% confidence interval 1. 42-45.8). No significant differences were observed for 51 Cr-EDTA clearance (CR Pre 90.4 ± 16.9, Post 96.1 ± 15.0 mL/min/1.73 m 2 ; PL Pre 97.9 ± 21.6, Post 96.4 ± 26.8 mL/min/1.73 m 2 ; p = 0.58; estimated difference between means -0.3; 95% confidence interval -24.9 to 24.2). Creatinine clearance, serum and urinary urea, electrolytes, proteinuria, and albuminuria were unchanged. CR supplementation does not affect kidney function in type 2 diabetic patients, opening a window of opportunities to explore its promising therapeutic role in this population. ClinicalTrials.gov registration number: NCT00992043.

The skeletal muscle was always seen from biomechanical and biochemical views. It is well-established that an active muscle brings many benefits for different body organs and tissues, including the immune system. Since the 1970s, many studies have shown the importance of regular exercise and physical activity in increasing the body's ability to fight opportunist infections, as well as a strategy to fight established diseases. This interaction was mainly attributed to the glutamine, a non-essential amino acid produced by the active skeletal muscle and primarily consumed by rapidly dividing cells, including lymphocytes and monocytes/macrophages, as their main source of energy. Therefore, these cells' function would be significantly improved by the presence of a bigger glutamine pool, facilitating phagocytosis, antigen-presentation, proliferative capacity, cytokine synthesis and release, among other functions. Despite its importance, glutamine is not the only molecule to connect these two tissues. The presence of cytokines is crucial for a proper immune system function. Many of them have well-established pro-inflammatory properties, while others are known for their anti-inflammatory role. Interleukin-6 (IL-6), however, has been in the center of many scientific discussions since it can act as pro-and anti-inflammatory cytokine depending on the tissue that releases it. Skeletal muscle is an essential source of IL-6 with anti-inflammatory properties, regulating the function of the immune cells after tissue injury and the healing process. Therefore, this review aims to discuss further the role of these four components (glutamine, and interleukin-6, and its interface with monocytes/macrophages, and lymphocytes) on the communication between the skeletal muscle and the immune system.

Sarcopenia is one of the main issues associated with the process of aging. Characterized by muscle mass loss, it is triggered by several conditions, including sedentary habits and negative net protein balance. According to World Health Organization, it is expected a 38% increase in older individuals by 2025. Therefore, it is noteworthy to establish recommendations to prevent sarcopenia and several events and comorbidities associated with this health issue condition. In this review, we discuss the role of these factors, prevention strategies, and recommendations, with a focus on protein intake and exercise.

BackgroundThe aim of this study was to determine the effects of creatine supplementation on kidney function in resistance-trained individuals ingesting a high-protein diet.MethodsA randomized, double-blind, placebo-controlled trial was performed. The participants were randomly allocated to receive either creatine (20 g/d for 5 d followed by 5 g/d throughout the trial) or placebo for 12 weeks. All of the participants were engaged in resistance training and consumed a high-protein diet (i.e., ≥ 1.2 g/Kg/d). Subjects were assessed at baseline (Pre) and after 12 weeks (Post). Glomerular filtration rate was measured by 51Cr-EDTA clearance. Additionally, blood samples and a 24-h urine collection were obtained for other kidney function assessments.ResultsNo significant differences were observed for 51Cr-EDTA clearance throughout the trial (Creatine: Pre 101.42 ± 13.11, Post 108.78 ± 14.41 mL/min/1.73m2; Placebo: Pre 103.29 ± 17.64, Post 106.68 ± 16.05 mL/min/1.73m2; group x time interaction: F = 0.21, p = 0.64). Creatinine clearance, serum and urinary urea, electrolytes, proteinuria, and albuminuria remained virtually unchanged.ConclusionsA 12-week creatine supplementation protocol did not affect kidney function in resistance-trained healthy individuals consuming a high-protein diet; thus reinforcing the safety of this dietary supplement.Trial registrationClinicalTrials.gov NCT01817673

In this paper, one of the authors' names, Vitor de Salles Painelli, appeared incorrectly. The author's name is correct in this erratum.The publisher sincerely apologizes for any inconvenience this might have caused.