Type 2 diabetes (T2D) affects a large part of the adult population and impairs its quality of life. Because of this, natural compounds with antioxidant, anti-inflammatory and hypoglycemic properties have been used as adjuvants. Among these compounds, resveratrol (RV) stands out, a polyphenol that has been studied in several clinical trials, the results of which are controversial. We conducted a randomized clinical trial on 97 older adults with T2D to evaluate the effect of RV on oxidative stress markers and sirtuin 1, using doses of 1000 mg/day (EG1000, n = 37) and 500 mg/day (EG500, n = 32) compared with a placebo (PG, n = 28). Biochemical markers, oxidative stress and sirtuin 1 levels were measured at baseline and after six months. We observed a statistically significant increase (p < 0.05) in total antioxidant capacity, antioxidant gap, the percentage of subjects without oxidant stress and sirtuin 1 levels in EG1000. In the PG, we observed a significant increase (p < 0.05) in lipoperoxides, isoprostanes and C-reactive protein levels. An increase in the oxidative stress score and in the percentage of subjects with mild and moderate oxidative stress was observed too. Our findings suggest that 1000 mg/day of RV exerts a more efficient antioxidant effect than 500 mg/day.

Alpha-lipoic acid (ALA) has been used as a dietary supplement at different doses in patients with diabetes mellitus type 2 (T2DM) due to its antioxidant, anti-inflammatory, and hypoglycemic effects. However, the reports on the effects of ALA are controversial. For this reason, the purpose of the present study was to determine the effect of 600 mg/day of ALA on the markers of oxidative stress (OxS) and inflammation and RAGE in older adults with T2DM. A quasiexperimental study was carried out with a sample of 135 sedentary subjects (98 women and 37 men) with a mean age of64±1years, who all had T2DM. The sample was divided into three groups: (i) experimental group (EG) with 50 subjects, (ii) placebo group (PG) with 50 subjects, and control group (CG) with 35 subjects. We obtained the following measurements in all subjects (pre- and posttreatment): glycosylated hemoglobin (HbA1c), receptor for advanced glycation end products (RAGE), 8-isoprostane, superoxide dismutase (SOD), glutathione peroxidase (GPx), total antioxidant status (TAS), and inflammatory (CRP, TNF-α, IL-6, IL-8, and IL-10) markers. Regarding the effect of ALA on HbA1c, a decrease was observed in the EG (baseline8.9±0.2vs. posttreatment8.6±0.3) and the PG (baseline8.8±0.2vs. posttreatment8.4±0.3) compared to the CG (baseline8.8±0.3vs. six months9.1±0.3) although the difference was not statistically significant (p<0.05). There was a statistically significant decrease (p<0.05) in the blood concentration of 8-isoprostane in the EG and PG with respect to the CG (EG: baseline100±3vs. posttreatment57±3, PG: baseline106±7vs. posttreatment77±5, and CG: baseline94±10vs. six months107±11pg/mL). Likewise, a statistically significant decrease (p<0.05) in the concentration of the RAGE was found in the EG (baseline1636±88vs. posttreatment1144±68) and the PG (baseline1506±97vs. posttreatment1016±82) compared to CG (baseline1407±112vs. six months1506±128). A statistically significant decrease was also observed in all markers of inflammation and in the activity of SOD and GPx in the CG with respect to the EG and PG. Our findings suggest that the administration of ALA at a dose of 600 mg/day for six months has a similar effect to that of placebo on oxidative stress, inflammation, and RAGE in older adults with T2DM. Therefore, higher doses of ALA should be tried to have this effect. This trial is registered with trial registration numberISRCTN13159380.

Background: Several clinical trials have suggested that resveratrol has hypoglycemic properties; however, there are other studies in which such an effect has not been observed. Methods: We carried out a systematic search in several databases; seventeen studies were selected for the systematic review and fifteen were included in the meta-analysis. Results: Resveratrol decreases glucose levels in subjects aged 45–59 years at doses <250 mg/day (−8.64 mg/dL, p < 0.00001), 250–500 mg/day (−22.24 mg/dL, p = 0.0003), and 500–1000 mg/day (−28.40 mg/dL, p = 0.0008), while in subjects older than 60 years, it only decreases with doses of 250–500 mg/day. Likewise, HbA1c improved in subjects aged 45–59 years with doses of 250–500 mg (−0.60%, p < 0.00001), but not in subjects older than 60 years. Insulin levels improved in subjects aged 45–59 years with doses < 250 mg/day (−0.80 mIU/L, p = 0.0003) and doses of 250–500 mg/day (−5.0 mIU/L, p = 0.0003), although in subjects older than 60 years, they only improved with doses of 250–500 mg/day (−1.79 mIU/L, p = 0.01). On the other hand, HOMA-IR only improved in subjects older than 60 years with doses of 250–500 mg/day (−0.40, p = 0.01). Conclusions: Resveratrol has a statistically significant dose–response effect on glucose concentrations, HbA1c, and insulin levels; however, there is not enough scientific evidence to propose a therapeutic dose.

Resveratrol (RV) is a polyphenolic compound with antioxidant, anti-inflammatory, and hypoglycemic properties. Several in vitro and animal model studies have demonstrated the beneficial effects of RV; however, the results in humans are not conclusive. After a search of different databases, 32 studies were selected for this systematic review and 30 were included in the meta-analysis. Studies that evaluated the effect of RV on glucose, insulin, HbA1c, and insulin resistance (HOMA-IR) levels were included. A significant decrease of glucose (−5.24 mg/dL, p = 0.002) and insulin levels (−1.23 mIU/L, p = 0.0003) was observed. HbA1c and HOMA-IR did not show significant changes. Due to heterogeneity, sub-analyzes were performed. Sub-analysis by dose revealed that glucose levels improve significantly after the administration of 500–1000 mg/day of RV (−7.54 mg/dL, p = 0.002), while insulin improves with doses lower than 500 mg/day (−1.43 mIU/L, p = 0.01) and greater than 1000 mg/day (−2.12 mIU/L, p = 0.03). HbA1c and HOMA-IR remained unchanged after sub-analysis by dose. Our findings suggest that RV improves glucose and insulin levels in subjects with type 2 diabetes mellitus (T2DM) and aged 45–59 years, regardless of the duration of the intervention. HbA1c improves with interventions ≥3 months. HOMA-IR does not exhibit significant changes after RV administration.

Introducción En la actualidad las mejores prácticas clínicas se ejercen acorde con el enfoque y metodología de la “medicina basada en evidencia” (MBE); definida como el uso consciente, responsable y explícito de la mejor evidencia científica disponible para la toma de decisiones clínicas. La MBE es especialmente útil en la planificación del tratamiento más apropiado para los pacientes, y para ello es imperativo integrar la experiencia y habilidades clínicas con los resultados derivados de las investigaciones científicas. En este sentido, existe un gran número de investigaciones científicas dentro del ámbito médico, lo que representa un gran desafío para los profesionales de la salud al momento de elegir la mejor evidencia. Derivado de ello surgieron las revisiones sistemáticas (RS), un tipo de investigación secundaria cuya finalidad es sintetizar de manera transparente y explícita toda o casi toda la evidencia científica disponible respecto a un tema en particular. Las RS parten de una pregunta clínica bien estructurada que da origen a una búsqueda exhaustiva, rigurosa y sistematizada para localizar la evidencia, misma que posteriormente es cuidadosamente seleccionada, sintetizada y evaluada para presentar de manera objetiva y neutral los hallazgos. Dado lo anterior las RS constituyen una herramienta esencial para facilitar el ejercicio de la MBE; no obstante, las RS no siempre representan la mejor evidencia disponible, ya que la información contenida en ellas puede no ser la más confiable. Esto implica diferenciar la evidencia confiable de la que no lo es, por lo que resalta indispensable contar con herramientas para evaluar y clasificar la evidencia. Ante esta situación, se han creado algunos sistemas como el modelo inglés Oxford Centre for Evidence-Based Medicine (OCEBM), el escocés Scottish Intercollegiate Guidelines Network (SIGN) o el estadounidense del American College of Chest Physicians (ACCP), que permitían categorizar la evidencia; sin embargo, debido a que fueron creados por consenso y opinión de expertos, presentaban variaciones entre ellos al categorizar una misma evidencia, disminuyendo la confiabilidad de la misma. Debido a las diferencias entre los sistemas para clasificar la evidencia, en 2004 surgió el Grupo de Trabajo GRADE (Grading of Recommendations Assessment, Development and Evaluation) (https://www.gradepro.org/). Este grupo está conformado por un grupo internacional de metodólogos, expertos en elaboración de guías de práctica clínica y de médicos clínicos, quienes han trabajado en la creación del sistema GRADE, una metodología rigurosa y transparente para evaluar la certeza de la evidencia (anteriormente llamada calidad de la evidencia), y con ello permitir a los profesionales de la salud elegir la mejor evidencia para la toma de decisiones. A continuación explicaremos en qué consiste la metodología GRADE.