Abstract
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Background: Diabetes Mellitus is a group of metabolic diseases characterized by
hyperglycemia resulting from defects in insulin secretion. insulin action, or both.The
chronic hyperglycemia of diabetes is associated with long-term damage, dysfunction,
and failure of several organs, especially the eyes, kidneys, nerves, heart, and blood
vessels.Type 2 diabetes the most prevalent form of the disease is often asymptomatic
and undiagnosed for many years. The risk of developing type 2 diabetes increases with
age, obesity, and lack of physical activity. Related to this, insulin resistance is a
fundamental aspect of the etiology of type 2 diabetes. This way, the majority of patients
who develop type 2 diabetes are insulin resistance, and the hyperglycemia occurs when
these patients can no longer support the degree of compensatory hyperinsulinemia
required to prevent gross decompensation of glucose homeostasis.The insulin
resistance has been shown to be associated with prevalent atherosclerosis,
hypertrigliceridemia, glucose intolerance, dyslipidemia, hyperuricemia, hypertension and
polycystic ovarian disease.The zinc seems to stimulate insulin action and insulin
receptor tyrosine Kinase activity. Objectives: To assess the effect of the zinc
supplementation in the primary prevention of type 2 diabetes mellitus. Search strategy:
We searched the Cochrane Metabolic Endocrine Group Specialised Register, the
Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library,
2005), MEDLINE (1966 to June 2005), EMBASE (1980 to June 2005), NIOSHTIC,
CISDOC, CINAHL, LILACS (1982 to June 2005) and Scientific Electronic Library
Online. The date of the last search was June 2005. Selection criteria: Studies were
included if they had a randomised and quasi-randomized design, if they were adults
living in the community, 18 years or older with insulin resistance and if there was some
kind of zinc supplementation (compared to placebo or no interventions). Data
collection & analysis: Two reviewers selected relevant trials, assessed methodological
quality and extracted data. There were no cases where the pooling of data was
appropriate. Main results: Only one study met the inclusion criteria of this review
(Marreiro 2002). There were no statistically significant difference favouring participants
receiving zinc supplementation compared to placebo concerning any outcome
measured by the study. Reviewers' conclusions: There is limited evidence to suggest
the use of zinc supplementation in the primary prevention of type 2 diabetes mellitus.
Future trials should have standardised outcomes measures such as incidence of type 2
diabetes mellitus, decrease of the insulin resistance, quality of life, mortality and costs.
Drop-outs and loss to follow up should be reported.