title: [Meta-analysis on the role of lycopene in type 2 diabetes mellitus].
abstract: BACKGROUND
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Unidad de Nutrición, Hospital 12 de Octubre, Madrid, España. mvalero.hdoc@salud.madrid.org
authors.forename: M A
authors.initials: MA
authors.lastname: Valero
authors.forename: A
authors.initials: A
authors.lastname: Vidal
authors.forename: R
authors.initials: R
authors.lastname: Burgos
authors.forename: F L
authors.initials: FL
authors.lastname: Calvo
authors.forename: C
authors.initials: C
authors.lastname: Martínez
authors.forename: L M
authors.initials: LM
authors.lastname: Luengo
authors.forename: C
authors.initials: C
authors.lastname: Cuerda
mesh_terms: D000975:Antioxidants / Q000378:metabolism / Q000627:therapeutic use*; D001786:Blood Glucose / Q000378:metabolism; D002338:Carotenoids / Q000097:blood / Q000627:therapeutic use*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism; D004032:Diet; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D000077276:Lycopene; D018551:Solanum lycopersicum; D008315:Malondialdehyde / Q000097:blood; D018384:Oxidative Stress; D014801:Vitamin A / Q000494:pharmacology; D014815:Vitamins / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D001786:Blood Glucose; D014815:Vitamins; D014801:Vitamin A; D002338:Carotenoids; D008315:Malondialdehyde; D000077276:Lycopene