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Trial registered on ANZCTR


Registration number
ACTRN12606000128594
Ethics application status
Approved
Date submitted
29/03/2006
Date registered
7/04/2006
Date last updated
7/04/2006
Type of registration
Prospectively registered

Titles & IDs
Public title
Salt & Hypertension & Diabetes
Scientific title
Does habitual low dietary sodium intake augment the response to angiotensin receptor blockade and thiazide therapy in hypertensive patients with type 2 diabetes and elevated albumin excretion rate?
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type 2 Diabetes 1093 0
Hypertension 1094 0
Microalbuminuria 1095 0
Condition category
Condition code
Metabolic and Endocrine 1174 1174 0 0
Diabetes
Cardiovascular 1175 1175 0 0
Hypertension

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure

Angiotensin 2 Receptor Agonists
Thiazide diuretics
Intervention code [1] 962 0
None
Comparator / control treatment
Salt and placebo capsules
Control group
Placebo

Outcomes
Primary outcome [1] 1584 0
1. Change in ambulatory blood pressure
Timepoint [1] 1584 0
From 0 to 4, 8 and from 14 to 18, 22 weeks
Primary outcome [2] 1585 0
2. Change in albumin excretion rate
Timepoint [2] 1585 0
From 0 to 4, 8, and from 14 to 18, 22 weeks
Secondary outcome [1] 2870 0
1. Acute response of effective renal plasma flow (ERPF) to captopril.
Timepoint [1] 2870 0
At baseline.
Secondary outcome [2] 2871 0
2. Acute response of renal resistance index (RI) to captopril.
Timepoint [2] 2871 0
At baseline.
Secondary outcome [3] 2872 0
3. Fasting plasma glucose at the time of ERPF and RI measurements.
Timepoint [3] 2872 0
Secondary outcome [4] 2873 0
4. BMI.
Timepoint [4] 2873 0
Secondary outcome [5] 2874 0
5. 24 h urinary sodium, potassium and creatinine excretion.
Timepoint [5] 2874 0
At 0, 4, 8, 14, 18, 22 weeks.
Secondary outcome [6] 2875 0
6. Plasma urea, creatinine and electrolytes, renin activity and aldosterone and fasting glucose and C-peptide.
Timepoint [6] 2875 0
At 0, 4, 8, 14, 18, and 22 weeks.
Secondary outcome [7] 2876 0
7. Haemoglobin A1C.
Timepoint [7] 2876 0

Eligibility
Key inclusion criteria
1. Type 2 diabetes mellitus.2. Hypertension (blood pressure >140/90 or taking antihypertensive therapy).3. Albumin excretion rate > 10 µg/min (median of three consecutive measurements).4. Urinary sodium excretion either > 200 mmole/24 hr on two out of three consecutive occasions (habitual high dietary sodium intake) or < 100 mmole/24 hr on two out of three consecutive occasions (habitual low dietary sodium intake). It is proposed to study 16 patients with habitual high dietary sodium intake and 16 patients with habitual low dietary sodium intake matched for BMI. Matching for BMI will be performed because of the documented association between total caloric intake and urinary sodium excretion in the DASH study.185. Caucasian ethnicity.
Minimum age
20 Years
Maximum age
80 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
1. Serum potassium > 5.0 mM.2. Serum creatinine > 200 µM.3. Albumin excretion rate > 200 µg/min.4. HbA1C > 10.0%.5. Major systemic illness.6. Drug dependence.7. Atrial fibrillation.8. Lactose intolerance (lactose capsules will be used as placebo).

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Randomised by pharmacy, investigator blinded
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation by using procedures such as coin-tossing and dice-rolling
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
1/05/2006
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
32
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 1283 0
Government body
Name [1] 1283 0
Austin Health
Country [1] 1283 0
Funding source category [2] 1284 0
University
Name [2] 1284 0
University of Melbourne
Country [2] 1284 0
Primary sponsor type
Individual
Name
Researcher Initiated Study- Professor George Jerums - Endocrine Centre of Excellence, Austin Health & University of Melbourne
Address
Country
Australia
Secondary sponsor category [1] 1136 0
None
Name [1] 1136 0
Nil
Address [1] 1136 0
Country [1] 1136 0

Ethics approval
Ethics application status
Approved

Summary
Brief summary
Lay Summary
Project Title: Does habitual low dietary sodium intake augment the response to angiotensin receptor blockade and thiazide therapy in hypertensive patients with type 2 diabetes and elevated albumin excretion rate?
Rationale:
One of the complications of type 2 (adult) diabetes and high blood pressure (BP) is diabetic kidney disease. In this disorder, the kidneys leak protein (albumin) into the urine and in early stages this is known as microalbuminuria. In some patients this progressively worsens, leading to kidney failure.
Some groups of blood pressure lowering medications also lower the blood pressure in the kidneys. This protects against kidney damage by slowing the progression of the protein leakage into the urine. The effectiveness of these groups of blood pressure tablets is reduced when the salt intake in the diet is high.
Aims of this study:
To determine if the effectiveness of the antihypertensive drug telmisartan, alone, and in combination with the drug hydrochlorothiazide, is increased by a low dietary salt (sodium chloride) intake, and if there is an additional beneficial effect on kidney function;
In this study, participants with type 2 diabetes, high blood pressure and early diabetic kidney disease (microalbuminuria) will be recruited. Two groups will be compared - those who usually have a high salt intake in their diet versus those who usually have a low salt intake in their diet, as determined by previous urine sodium test results. All patients will take antihypertensive medication to control their blood pressure called verapamil, prazosin and methyldopa, these medications do not interfere with the test results. The participants will continue their usual diet and dietary salt intake throughout the study, however they will take salt and placebo capsules at various times during the study to look at the effects of additional salt intake on blood pressure and kidney function in patients with high versus those with low dietary sodium intake.
Participants:
The participants (n=32) includes men and non-pregnant women aged 20-80, with type 2 diabetes, high blood pressure, early diabetic kidney disease and a high or low dietary salt intake.
Study Design and Procedures:
Cross-over double blind study design. The study involves 12 scheduled visits over 28 weeks.
The study consists of 3 phases: Two 8 week phases separated by a 6 week washout. Patients commence on verapamil ± prazosin ± methyldopa therapy and this is maintained throughout the 28 study period. The effect of telmisartan will be studied in each 8 week phase, and a thiazide will be added at week 4 to 8. The effect of salt or placebo will be examined in the last 2 weeks of each 4 week cycle.
During the study, a total of approximately 210 ml (10 tablespoons) of blood will be collected.

Potential side effects:
There are potential side effects of blood pressure lowering medications however as all the patients have high blood pressure, they will be on blood pressure lowering medications. This study involves exposure to a very small amount of radiation during nuclear medicine MAG 3 tests to look at kidney function. This has been approved by the radiation research subcommittee.

Provision of test results:
Participants (and their general practitioner with their consent) will have access to all laboratory tests and when the final study report is produced by the investigator, this will be forwarded to study participants in lay terms.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 36117 0
Address 36117 0
Country 36117 0
Phone 36117 0
Fax 36117 0
Email 36117 0
Contact person for public queries
Name 10151 0
Dr Elif I Ekinci
Address 10151 0
Endocrine Centre of Excellence
Heidelberg Repatriation Hospital
Austin Health
Level 2
Centaur Building
PO Box 5444
300 Waterdale Rd
West Heidelberg VIC 3081
Country 10151 0
Australia
Phone 10151 0
+61 3 94962410
Fax 10151 0
+61 3 94963365
Email 10151 0
[email protected]
Contact person for scientific queries
Name 1079 0
Dr Elif I Ekinci
Address 1079 0
Endocrine Centre of Excellence
Heidelberg Repatriation Hospital
Austin Health
Level 2
Centaur Building
PO Box 5444
300 Waterdale Rd
West Heidelberg VIC 3081
Country 1079 0
Australia
Phone 1079 0
+61 3 94962410
Fax 1079 0
+61 3 94963365
Email 1079 0
[email protected]

No information has been provided regarding IPD availability


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

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