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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Do omega-3 polyunsaturated fatty acids have a gender-specific effect on insulin resistance?
Scientific title
Do omega-3 polyunsaturated fatty acids have a gender-specific effect on insulin resistance? A double-blind randomized controlled trial
Secondary ID [1] 288663 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Insulin Resistance 297849 0
Obesity 297850 0
Condition category
Condition code
Diet and Nutrition 298023 298023 0 0
Metabolic and Endocrine 298063 298063 0 0

Study type
Description of intervention(s) / exposure
The intervention arm will receive 2 x 1g/day fish oil capsules (EPAX 1050 TG/N).
Each capsule containing 60mg EPA + 430mg DHA for 12 weeks.

Participants will be required to return unused tablets to assess compliance. In addition, omega-3 content in erythrocyte membranes will be measured at the start and the conclusion of the study in order to assess compliance.
Intervention code [1] 294079 0
Treatment: Other
Comparator / control treatment
Placebo arm will receive 2 x 1g/day corn oil capsules for 12 weeks.
Each capsule will contain 1g corn oil.
Control group

Primary outcome [1] 297539 0
Insulin Resistance (i.e. HOMA-IR, Matsuda Index)
HOMA-IR will be calculated using fasting plasma glucose and fasting plasma insulin measures. Matsuda Index will be calculated following a 2 hour Oral Glucose Tolerance Test, using plasma glucose and insulin values obtained at 0 mins and 120 mins post OGTT.
Timepoint [1] 297539 0
Baseline (week 0) and post intervention (week 12)
Primary outcome [2] 297540 0
Glycemic Profile (i.e. fasting plasma glucose, fasting plasma insulin, HbA1c in whole blood)
Timepoint [2] 297540 0
Baseline (week 0) and post intervention (week 12)
Secondary outcome [1] 321348 0
Lipid Profile (i.e. total cholesterol, LDL, HDL, TG in blood serum)
Timepoint [1] 321348 0
Baseline (week 0) and post intervention (week 12)
Secondary outcome [2] 321349 0
Inflammatory Profile (i.e. CRP, TNF-alpha, IL-6, IL-1beta, adiponectin in blood serum)
Timepoint [2] 321349 0
Baseline (week 0) and post intervention (week 12)
Secondary outcome [3] 321350 0
Erythrocyte Fatty Acid Composition. (Fatty acid composition of erythrocyte plasma membranes, assessed via Gas Chromatography)
Timepoint [3] 321350 0
Baseline (week 0) and post intervention (week 12)

Key inclusion criteria
1. Age – 18-70; gender – both males and females
2. No participation in any clinical trial for at least 3 months
3. BMI between 25-45kg/m2
4. Waist Circumference > 88cm (females) and 102cm (males)
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Pregnancy or lactation
2. Established type 2 diabetes
3. Have an electronic implant (e.g. pacemaker)
4. Currently taking anti-diabetic medications
5. Allergic to seafood or corn
6. Currently on medication with Aspirin and Warfarin
7. History of gastro-intestinal disorders
8. History of severe neurological diseases or seizures
9. History of new investigational drug three months prior to this trial
10. Consuming more than 2 serve of oily fish per week
11. Taking regular dietary supplements known to influence blood glucose level
12. Unwilling to fast for 10hr before obtaining blood sample

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Interested subjects will contact the study investigator who will then assess the subject's eligibility to participate over the phone. If the participant is deemed eligible, the participant will be sent a consent form, participant information statement and will be enrolled in the study. They will also be sent a series of self-administered questionnaires (medical history, physical activity, 3-day food record) along with instructions. All forms will need to be completed and returned upon baseline visit.
Allocation to treatments will be based on the computer generated block randomization method to ensure well-balanced groups. The allocation concealment will be conducted using sealed opaque envelopes
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Allocation to treatment will be based on the computer generated block randomization method. Males and females will be stratified to allow for gender sub-group analysis.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Sample size determination
Seventeen participants will give an 80% power to detect a 1.0 unit drop in HOMA-IR. To determine whether effects are gender-specific the sample size will be doubled to ensure an adequate sample of males and females. To allow for drop-outs 20 participants will be recruited to each group (males, placebo and intervention; females, placebo and intervention) giving a total of 80 participants.
Baseline data
Baseline measures will be used as covariates. Gender, BMI and other potentially confounding variables such as weight and age may be added as covariates if they are significantly correlated with the outcome measures.
Treatment effects
All the data relating the significant effects of n-3PUFA are expressed as mean ± SEM or median + IQR as appropriate. The effect of interventions on glucose tolerance, HOMA-IR, blood glucose levels and HbA1C between groups will be estimated by using two-way ANOVA with post hoc comparisons (Tukey’s honestly significant difference).
Significance (P-value set at 0.05) indicates the changes from the baseline values. Changes from the baselines will be determined using paired t-tests. This statistical analysis helps in determining whether there will be a significant main effect for each independent variable by testing for between subject effects. Sub-group analysis will allow investigators to investigate any gender-based differences in effect.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment postcode(s) [1] 12819 0
2308 - Newcastle University
Recruitment postcode(s) [2] 12820 0
2300 - Newcastle

Funding & Sponsors
Funding source category [1] 293021 0
Self funded/Unfunded
Name [1] 293021 0
Address [1] 293021 0
Country [1] 293021 0
Primary sponsor type
University of Newcastle
University Drive
Callaghan, NSW, 2308
Secondary sponsor category [1] 291797 0
Name [1] 291797 0
Address [1] 291797 0
Country [1] 291797 0

Ethics approval
Ethics application status
Ethics committee name [1] 294531 0
University of Newcastle Human Research Ethics Committee
Ethics committee address [1] 294531 0
University of Newcastle
University Drive
Callaghan, NSW, 2308
Ethics committee country [1] 294531 0
Date submitted for ethics approval [1] 294531 0
Approval date [1] 294531 0
Ethics approval number [1] 294531 0

Brief summary
Development of type 2 diabetes is closely linked with overweight and obesity. Due to the increasing prevalence of obesity in Australia, combined with an increasingly aged population, type 2 diabetes and associated health complications will become an increasingly burdensome public health problem in the near future. Epidemiological studies, as well as animal studies, suggest that a higher omega-3 status might be protective against obesity-related insulin resistance, however, intervention trials have had equivocal results. Recent evidence suggests that the effect of omega-3 polyunsaturated fatty acids on insulin resistance might be sex dependent. Therefore the aim of the current study is to determine whether there is a sex-dependent response on measures of insulin resistance to an omega-3PUFA intervention
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 64034 0
Prof Manohar Garg
Address 64034 0
305C Medical Sciences Building
University of Newcastle
University Drive
Callaghan, NSW, 2308
Country 64034 0
Phone 64034 0
+61 2 49215647
Fax 64034 0
+61 2 49212028
Email 64034 0
Contact person for public queries
Name 64035 0
Ms Kylie Abbott
Address 64035 0
305B Medical Sciences Building
University of Newcastle
University Drive
Callaghan, NSW, 2308
Country 64035 0
Phone 64035 0
+61 2 4021 5638
Fax 64035 0
+61 2 4921 2028
Email 64035 0
Contact person for scientific queries
Name 64036 0
Prof Manohar Garg
Address 64036 0
305C Medical Sciences Building
University of Newcastle
University Drive
Callaghan, NSW, 2308
Country 64036 0
Phone 64036 0
+61 2 4921 5647
Fax 64036 0
+61 2 4921 2028
Email 64036 0

No information has been provided regarding IPD availability
Summary results
No Results