Dietary Antioxidants and Thiol Disulfide Homeostasis in T2DM
Condition: Diabetes Mellitus, Type 2; Antioxidative Stress
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Observational

Summary: 
      This observational study was planned to determine the relationship between dietary
      antioxidant intake and thiol disulfide homeostasis of individuals with type 2 diabetes. One
      of the current approaches in medical nutrition therapy of diabetes is to increase the
      consumption of foods with high antioxidant content in order to strengthen antioxidant
      defense. Increased dietary antioxidant intake may have both protective and therapeutic
      effects by reducing the risk of diabetes and preventing complications that may occur. It is
      known that dynamic thiol disulfide balance can be a good indicator of antioxidant defense in
      individuals with diabetes, and there are limited studies on this subject.
    

Detailed description: 
      Power analysis was performed to determine the study sample. In order to reveal a moderate to
      high level effect for each parameter with 80% power and 5% margin of error, it was found
      appropriate to work with a total of 68 people, 34 of whom were T2DM and 34 of whom were
      healthy. In order to keep the sample size higher, a total of 87 individuals, including 40
      T2DM and 47 healthy individuals, were included in this study. Individuals who agreed to
      participate in the study gave their informed consent. Anthropometic measurements (body weight
      and height) were taken by the researcher. BMI values of individuals were calculated with the
      formula of body weight (kg)/height (m)2 Routine fasting plasma glucose (FPG), hemoglobin A1c
      (HbA1c), total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density
      lipoprotein (LDL) cholesterol, very low-density lipoprotein (VLDL), non-HDL cholesterol,
      Total/HDL cholesterol ratio, triglyceride (TG), C-reactive protein (CRP) values were analyzed
      with blood samples taken by the nurse on an 8 hours of fasting in the morning. Dynamic thiol
      disulfide balance was determined by native thiol, total thiol and disulfide values and
      oxidized albumin was determined by IMA values. Food consumption records of individuals were
      taken to determine dietary antioxidant intake and dietary antioxidant capacity. Oxidative
      balance score was used to evaluate the exposure of individuals to antioxidants and
      prooxidants. Descriptive statistics for categorical variables are presented as frequency and
      percentage. The conformity of the numerical variables to the normal distribution was checked
      using the Shapiro-Wilk Test. The descriptive statistics of numerical variables were given as
      mean (±) standard deviation for those with normal distribution, and median interquartile
      range [IQR] values for those without normal distribution. In the comparison of two
      independent groups; Independent Sample T Test was used if the data provided the assumptions
      of the parametric tests, the Mann-Whitney U Test was used if the assumptions of the
      parametric tests were not met, and the Chi-square Test was used for the comparison of two
      qualitative groups. Examination of the relationships between quantitative variables was
      determined by the "Pearson Correlation Coefficient" for those with normal distribution and
      the Spearman Correlation Coefficient for those who did not. In the interpretation of the
      correlation coefficient, very weak correlation criteria were used if <0.2, weak correlation
      between 0.2-0.4, moderate correlation between 0.4-0.6, high correlation between 0.6-0.8, and
      very high correlation if 0.8>. Statistical significance level was considered as α<0.05,
      α<0.01, α<0.001 in all calculations and interpretations and hypotheses were established as
      bidirectional. Statistical analysis of the data was performed with SPSS v26 (IBM Inc.,
      Chicago, IL, USA) statistical package program.
    

Intervention name(s): Dietary antioxidant intake
Intervention type(s): Other
Intervention description(s): Decreased intake of dietary antioxidant is associated with decreased thiol disulfide homeostasis parameters in diabetic and healthy participants.
Intervention MeSH terms: Antioxidants
Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Participants who applied to Ankara City Hospital Endochronology Polyclinic between January
        and April 2021.
      
Biospecimen description: 
      Fasting blood samples of each participants were retained in a biorepository to assess native
      thiol, total thiol, disulfide and ischemia modified albumin until the analysis as described:
      To prevent the reduction of 5,5'-dithiobis-(2-nitrobenzoic) acid, the unused reducing sodium
      borohydride was consumed and removed with formaldehyde, and after the reaction with
      5,5'-dithiobis-(2-nitrobenzoic) acid, all thiol groups including the reduced and native thiol
      groups were determined.IMA level measurement was made within 1 hour after the venous blood
      samples of the individuals were taken. The samples were incubated at room temperature for 30
      minutes and then centrifuged at 3500 rpm for 5 minutes. Final samples were transferred to
      Eppendorf tubes and stored at -80ºC until analysis. The samples were incubated at room
      temperature for 30 minutes and then centrifuged at 3500 rpm for 5 minutes. Final samples were
      transferred to Eppendorf tubes and stored at -80ºC until analysis.
    
Keywords: Diabetes mellitus; Dietary antioxidants; Oxidative stress; Thiol disulfide homeostasis