diabetes is a relatively prevalent disease that occurs as a result of lack or dysfunction of insulin . approximately 6% american have different levels of glucose metabolism disorder , which indicate diabetes or the tendency to have diabetes . according to who , the prevalence of type 2 diabetes was estimated to be 5.5 , 5.7 , and 6.8% in 1995 , 2000 , and 2005 , respectively . stephens et al . studied the biological relationship and measured plasma markers of oxidative stress in diabetic and cardiovascular patients and found a close relationship between diabetes mellitus and increased oxidative stress . adiposity and a longer duration of obesity are important risks factors for type 2 diabetes , and even little weight losses are associated with a maodulataion of hyperglycemia in persons with prediabetes . review studies have shown that the level of free radicals increases and the level of antioxidants decreases during diabetes . linoleic acid ( omega-6 ) and linolenic acid ( omega-3 ) have important roles in body functions , but they can not be produced in the absence or lack of an enzyme . mori et al . studied the effect of epa , dha , and olive oil on oxidative stress and biochemical parameters of patients with type 2 diabetes and found that epa and dha reduce oxidative stress without changing inflammatory markers in patients with type 2 diabetes . thorsdottir et al . , from iceland concluded that omega-3 fatty acids in milk reduces type 2 diabetes in men . lean et al . concluded that omega-3 fatty acids significantly reduce serum lipids and control serum sugar in patients with type 2 diabetes . with regard to high prevalence and irreparable complications of diabetes , there is probable role of free radicals in the developmentand progress of the disease as well as the fact that omega-3 fatty acids have extensive biological effects on lipoprotein metabolism , platelet function , cytokine production , clotting , fibrinolysis , and inflammatory factors . hajianfar et al . found that omega-3 reduced weight in the case group that used omega-3 vs. control group . this study aimed to investigate the effect of omega-3 fatty acid supplement on antioxidant capacity of patients with type 2 diabetes . the study population consisted of 45 - 65 year - old women with type 2 diabetes admitted to shariaty clinic in isfahan . considering the extra 15% , sample size in each group thirty - seven volunteers were recruited in the case group and 34 entered the placebo group after signing the informed written consent form . inclusion criteria were type 2 diabetes for at least 5 years , no insulin shot , no secondary complications of diabetes such as ophthalmologic complications , renal complications , amputation , renal diseases , blindness , cardiovascular diseases , and no high crp . at the beginning of study , then , the subjects received supplement or placebo according to the groups for 8 weeks . at the end of study , we measured anthropometric and biochemical indices again . a digital scale ( seca ) was used to measure weight with an accuracy of + 100 g . height was measured without shoes to the nearest 0.5 cm with the use of a commercial stadiometer with the shoulders in relaxed position and arms hanging freely . body mass index ( bmi ) was calculated by dividing weight ( kg ) by height ( m ) . both the lab technician and the patients were unaware of the intervention . fisher 's exact test was used for qualitative information , t test was used for quantitative test , chi square test was used for weight changes , and pearson 's correlation test was used for data correlation . the results showed that the omega-3 group and placebo group were not significantly different in terms of age , education , and occupation . furthermore , other variables like comorbid diseases , medication , and diet were not significantly different between the two groups . mean age of patients was 53.6  4.3 and 53.9  5.4 in the case and control groups , respectively . according to t test , no significant difference was found between the two groups in this regard ( p = 0.79 ) . mean of serum age , bmi , weight , hba1c concentration and antioxidant capacity and comparison of the changes before and after intervention at two groups is showen in table 1 and 2 . mean of age , bmi , weight , concentration of serum hba1c and antioxidant capacity before and after intervention at two groups comparison of changes in anthropometric and biochemical indices between two groups ( 3 and placebo ) a digital scale ( seca ) was used to measure weight with an accuracy of + 100 g . height was measured without shoes to the nearest 0.5 cm with the use of a commercial stadiometer with the shoulders in relaxed position and arms hanging freely . body mass index ( bmi ) was calculated by dividing weight ( kg ) by height ( m ) . both the lab technician and the patients were unaware of the intervention . fisher 's exact test was used for qualitative information , t test was used for quantitative test , chi square test was used for weight changes , and pearson 's correlation test was used for data correlation . the results showed that the omega-3 group and placebo group were not significantly different in terms of age , education , and occupation . furthermore , other variables like comorbid diseases , medication , and diet were not significantly different between the two groups . mean age of patients was 53.6  4.3 and 53.9  5.4 in the case and control groups , respectively . according to t test , no significant difference was found between the two groups in this regard ( p = 0.79 ) . mean of serum age , bmi , weight , hba1c concentration and antioxidant capacity and comparison of the changes before and after intervention at two groups is showen in table 1 and 2 . mean of age , bmi , weight , concentration of serum hba1c and antioxidant capacity before and after intervention at two groups comparison of changes in anthropometric and biochemical indices between two groups ( 3 and placebo ) the main objective of this study was to determine the effect of omega-3 supplement on antioxidant capacity of patients with diabetes type 2 . the results show that taking omega-3 supplement increases antioxidant capacity and reduces hba1c in patients with type 2 diabetes . this finding shows the role of omega-3 supplement in controlling hba1c , which is a criterion to evaluate the control level of serum glucose in diabetes . omega-3 consumption reduced hba1c in diabetic patients , but this change was not significant in kesuvalu 's study . several studies confirm the results of this study about increase in antioxidant capacity after taking omega-3 supplement . suresh et al . , concluded that omega-3 can improve oxidative stress in diabetes , which corresponds with the result of the present study . mori et al . , found that epa and dha reduced oxidative stress in type 2 diabetes . , samaoui et al . , studied the relationship between fat in diet and antioxidants in diabetic patients and found that antioxidant capacity in diabetic patients who did not control diabetes well was reduced . reported an increase in antioxidant capacity of diabetic patients , which is in line with our findings . pasaogala et al . , ( 2004 ) found that the level of oxidative stress in patients with type 2 diabetes was higher than that in the control group . the amount of free radicals in patients with type 2 diabetes increases and antioxidant resistance reduces , therefore oxidative stress increases in such people . kasuvalu showed that omega-3 reduced free radicals and increased antioxidant enzymes in this group , which is in line with our finding . antioxidants reduce in these patients because increased free radicals cause different diseases including diabetes , and weaken antioxidant system . tayyebi - khosroshahi concluded that omega-3 in hemodialysis patients increased antioxidant factors like glutathione peroxide and superoxide mutase hiratsuka found that dha rich diet has antioxidant activity in rat 's brain . this study resulted in the following , aiming to investigate the effect of omega-3 supplement on antioxidant capacity of patients with type 2 diabetes . hba1c and antioxidant capacity in these people were significant , indicating that the intervention was useful and increased antioxidant capacity in these people . considering the probable role of antioxidant system in causing type 2 diabetes , we can prevent type 2 diabetes in healthy people and reduce diabetes complications and its progress by boosting their antioxidant defense system . some studies found a significant relationship between the level of serum visfatin and bmi of the participants.[2326 ] this finding is against the findings of pagano et al . , on non - diabetic people with different weights ; they found an inverse relationship between bmi and visfatin . furthermore , chen et al . , found a significant relationship between serum visfatin and bmi in patients with type 2 diabetes . since weakening of antioxidant system can cause diabetes and because findings of the present study showed that omega-3 supplement can increase antioxidant capacity , consumption of omega-3 supplement is recommended as primary prevention and secondary prevention of diabetes complications . since weakening of antioxidant system can cause diabetes and because findings of the present study showed that omega-3 supplement can increase antioxidant capacity , consumption of omega-3 supplement is recommended as primary prevention and secondary prevention of diabetes complications .
background : diabetes is one of the most common chronic diseases in which antioxidant capacity changes . omega-3 fatty acids have extensive biological effects including their advantage on lipoprotein metabolism , platelet function , cytokine production , clotting , fibrinolysis , and inflammatory factors . 
 this study aimed to investigate the effect of omega-3 fatty acid supplements on antioxidant capacity in patients with type 2 diabetes.methods:this clinical trial enrolled 71 women with type 2 diabetes in two case ( treated with omega-3 capsules ) and control ( treated with placebo ) groups . in the first stage , participants filled out a demographics questionnaire including age , height , weight , waist circumference , and hip circumference.their blood sample was taken to evaluate glycosylated hemoglobin and antioxidant capacity . 
 then the case group received intervention for 8 weeks and weight , waist circumference , and hip circumference were measured and a blood sample was taken again . 
 the data were analyzed using spss 18 software.results:the mean difference of antioxidant capacity before and after intervention was significant ( p < 0.001 ) . 
 antioxidant capacity increased in the case group and reduced in the control group.conclusions:with regard to the results of the present study , patients with type 2 diabetes increase their antioxidant capacity , enhance their antioxidant defense system , and probably prevent diabetes complications and related disease progress by taking omega-3 supplements .