The Effect of Amlodipine and Lisinopril on Retinal Autoregulation in Type 1 Diabetes

Study Overview
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Brief Summary
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The purpose of this study is to compare the effect of two antihypertensive drugs on retinal vessel diameter in young type 1 diabetics. The retinal vessel analyzer (RVA) was used to investigate how the drugs affected vessel diameter, when the subjects were exposed to an increase in blood pressure, induced by isometric muscle contraction and when they were stimulated by flickering light.

Detailed Description
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Diabetes is a leading cause of blindness in the western part of the world. Diabetic patients develop diabetic retinopathy which can progress to blindness. Diabetic retinopathy is associated with an increase of blood flow in the retinal vessels, ischaemia in the periphery and macular oedema. It has been shown in previous trials, that the pressure and metabolic autoregulation is disturbed in patients with diabetes, and it is believed to contribute to the development of diabetic retinopathy. In healthy subjects the retinal arterioles will contract during an increase in blood pressure, but trials have shown that this response is impaired in diabetics. When the retina is exposed to flickering lights, the metabolism increase and the arterioles in healthy subjects dilates. In diabetics this dilation is impaired. In this trial we want to investigate if an ACE-inhibitor (lisinopril) or calcium channel blocker (amlodipine) influence this response in subjects exposed to increased blood pressure vs increased retinal metabolism.

Official Title
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Lack of Effect of Antihypertensive Treatment With Amlodipine and Lisinopril on Retinal Autoregulation in Patients With Type 1 Diabetes and Mild Diabetic Retinopathy. A Prospective Randomized Clinical Trial.

Conditions
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Diabetic Retinopathy, Type 1 Diabetes, Eye Diseases, Diabetes Complications

Intervention / Treatment
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* Drug: Amlodipine
* Drug: Lisinopril


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Type 1 diabetes 18-35 years of age Simplex retinopathy at last screening (Less than 10 retinal haemorrhages at the nearest ordinary screening examination) normotensive (BP not above 160 mmHg systolic or 100 mmHg diastolic) Exclusion Criteria: Pregnancy Systolic Bloodpressure above 160 mmHg Diastolic bloodpressure above 100 mmHg Retinopathy grade higher than simplex retinopathy Prior retinal laser photocoagulation

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Crossover design. Arm is same all the way | Drug: Amlodipine<br>* 1 (5mg) tablet daily, given 14 days totally before measure of outcome.<br>Drug: Lisinopril<br>* Lisinopril 10 mg given daily for 14 days and then outcome was measured.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Vessel diameter changes in arbitrary units as measured with the Retinal Vessel Analyzer |  | 120,240,360,480,600,720 and at 840secs | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood pressure (mmHG) |  | 120,240,360,600,720,840 secs | 
| 24 hour ambulatory blood pressure (mmHg) |  | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Diabetes, Retinopathy, Blood Pressure, Amlodipine, Lisinopril