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Restoration of Retinal Vascular Responses in Type 1 Diabetic Patients

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02099981
Recruitment Status : Completed
First Posted : March 31, 2014
Last Update Posted : January 18, 2018
Information provided by (Responsible Party):
University of Minnesota

Brief Summary:

Diabetic retinopathy is the leading cause of blindness in the developed world. The causes of the disease are poorly understood. One of the earliest changes that occur in the retinas of diabetic patients, well before overt retinopathy is observed, is a reduction in light-evoked increases in blood flow in retinal vessels. The loss of this vascular response may lead to retinal hypoxia and it has been suggested that hypoxia could be a principal cause of diabetic retinopathy.

The long-term goals of this project are to determine whether decreased blood flow in diabetic patients and the resulting retinal hypoxia contributes to the development of diabetic retinopathy and whether restoration of normal blood flow in diabetic patients slows or prevents the development of retinopathy.

Condition or disease Intervention/treatment Phase
Diabetic Retinopathy Drug: Aminoguanidine Phase 1

Detailed Description:

The immediate goal of the proposed project is to determine whether administration of aminoguanidine (AG) restores light--evoked vasodilations in the retinas of patients without advanced retinopathy. We will also determine whether AG improves contrast sensitivity in diabetic patients. The proposed experiments are as a first step in developing new therapies to prevent diabetic retinopathy.

Study participants will be asked to come to the University of Minnesota on three (3) occasions (the visits will last for up to 2, 5 and 3 hours respectively).

Visit 1. During the screening visit (first and shortest visit), consent will be obtained and baseline labs collected (Hemoglobin A1c and Creatinine). Demographic information (date of birth, gender, race), subjects characteristics (weight, height, blood pressure and pulse) and relevant medical history will be recorded.

Visit 2. Vessel dilation testing: Control and diabetic subjects will present to the Ophthalmology Research Unit at the University of Minnesota. Prior to the imaging examination, each subject will receive dilating eye drops (1% Tropicamide) to prevent accommodation of the pupil and brief eye exam will be performed. Measurement of resting vessel diameter and light--evoked vessel dilation will be made using the Imedos Systems "Dynamic Vessel Analyzer". Subjects will be instructed to look at a fixation spot and a 350 s sequence of fundus images will be acquired during baseline and stimulation period. After completion of the initial vasodilation measurements, both control and diabetic subjects will be given 150 mg AG orally and measurement of resting vessel diameter and light--evoked vasodilation will be repeated 90 minutes later.

Visit 3. Contrast sensitivity testing: Contrast sensitivity will be assessed in un-dilated control and diabetic subjects. Contrast sensitivity will be determined both before and after AG administration using a CSV-100 test chart (VectorVision) and will be measured at 3, 6, 12, and 18 cycles per degree.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 34 participants
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Restoration of Retinal Vascular Responses in Type 1 Diabetic Patients
Actual Study Start Date : July 2016
Actual Primary Completion Date : December 2017
Actual Study Completion Date : December 2017

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: Control Group
Control subjects will receive AG.
Drug: Aminoguanidine
Other Name: AG

Experimental: Type 1 diabetes
Type 1 diabetic subjects will receive AG.
Drug: Aminoguanidine
Other Name: AG

Primary Outcome Measures :
  1. The vascular response to flicker [ Time Frame: 90 minutes ]
    The vascular response will be defined as the ratio of the maximal vessel diameter observed during the stimulation period, compared to the mean diameter during the control period

Secondary Outcome Measures :
  1. Contrast sensitivity [ Time Frame: 90 minutes ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Type 1 diabetes between 18 and 65 years of age
  • Diabetes duration between 5 to 20 years.
  • Normal report or minor findings on a dilated eye exam
  • Healthy subjects on no medications

Exclusion Criteria:

Current diagnosis or history of:

  • hypertension
  • dyslipidemia
  • epilepsy
  • glaucoma or other ocular disease
  • renal insufficiency/failure (creatinine >1.5 mg/dL)
  • pregnancy or breastfeeding.
  • smoker

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02099981

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United States, Minnesota
University of Minnesota Medical Center Fairview
Minneapolis, Minnesota, United States, 55455
Sponsors and Collaborators
University of Minnesota
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Principal Investigator: Elizabeth Seaquist, MD University of Minnesota
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Responsible Party: University of Minnesota Identifier: NCT02099981    
Other Study ID Numbers: Protocol 22503
First Posted: March 31, 2014    Key Record Dates
Last Update Posted: January 18, 2018
Last Verified: January 2018
Keywords provided by University of Minnesota:
Additional relevant MeSH terms:
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Retinal Diseases
Diabetic Retinopathy
Eye Diseases
Diabetic Angiopathies
Vascular Diseases
Cardiovascular Diseases
Diabetes Complications
Diabetes Mellitus
Endocrine System Diseases
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action