[Meta-analysis on the role of lycopene in type 2 diabetes mellitus]. / Meta-análisis del papel del licopeno en la diabetes mellitus tipo 2.

INTRODUCTION: lycopene is a carotene with a potent antioxidant effect found in tomato and its derivatives. Given that diabetic patients present an increased oxidative stress, lycopene could be beneficial. The aim of this scientific review has been to analyze the scientific evidence of the role of lycopene as an anti-oxidant agent in diabetes, its prevention and the metabolic control and development of complications. MATERIALS AND METHODS: We carried out a systematic review and meta-analysis. A literature search was done in Medline and the Cochrane Library, using the MeSH terms "carotenoids" OR "lycopene" AND "type 2 diabetes mellitus". The search was manually completed from the references of the papers found. The quality of the studies was assessed by using the JADAD and STROBE scales. We included a total of 10 articles. RESULTS: After adjusting for other risk factors, the OR for developing DM2 as similar among the different levels of lycopene intake. The plasma levels of lycopene increase in the intervention groups. Lycopene decreases the malonyldialdehyde and lipid peroxidation. The non-provitamin A/provitamin A carotenoids ratio is negatively associated with the risk for suffering from diabetic retinopathy. CONCLUSION: Tomato or lycopene intake increases the plasma levels of this compound. However, there is no evidence for the association between lycopene intake and the risk for having diabetes. This compound and other tomato derivatives may have a beneficial effect on the oxidative stress in diabetic patients. The non-provitamin A/provitamin A carotenoids ratio is negatively associated with the risk for suffering from diabetic retinopathy, although there are no data available on the relationship between lycopene and other diabetic complications.

[Antioxidants and diabetes mellitus: review of the evidence]. / Antioxidantes y diabetes mellitus: revisión de la evidencia.

INTRODUCTION: An increase in the oxidative stress and a decrease in the antioxidant levels have been described in diabetic patients, that have been related with the etiopathogenesis of diabetes and its chronic complications. METHODS: We performed a non-systematic review to evaluate the relationship between oxidative stress and diabetes, and the possible effects of antioxidants in the prevention and treatment of diabetes and its complications. RESULTS: The intervention studies including different antioxidants have not demonstrated any beneficial effect on cardiovascular and global morbimortality in different populations, including diabetic patients. Neither of these studies has demonstrated a beneficial effect of antioxidant supplementation on the prevention of diabetes. According to these studies, these substances can decrease lipid peroxidation, LDL-cholesterol particles oxidation and improve endothelial function and endothelial-dependent vasodilatation, without significant improvement in the metabolic control of these patients. CONCLUSIONS: The current evidence does not support the use of high doses of antioxidants on the prevention and treatment of diabetes and its complications.