Vascular Reparative Mechanism in Diabetes (RAAS)

Vascular Reparative Mechanism by ACE2/Ang-(1-7) in Diabetes

The purpose of this research study is to study blood stem cells in diabetic patients and normal patients. We would like to better understand if these cells, called endothelial precursor cells (EPCs), are not working as expected in people with diabetes. We would like to see if the function of these cells can predict the development of diabetic retinopathy.

Diabetic retinopathy is an eye disease associated with diabetes in which the cells of the retina are damaged. It can cause blurred vision, vision loss, blindness or possible bleeding in the retina. Even with current treatments, the quality of life for people with diabetic retinopathy is much reduced.

Study Overview

• Status: Active, not recruiting
• Conditions: Diabetic Retinopathy
• Intervention / Treatment: Other: Diabetic Patients; Other: Healthy Controls

• Study Type: Observational
• Enrollment (Estimated): 78

Contacts and Locations

Study Locations

• United States
  • Alabama
    • Birmingham, Alabama, United States, 35294
      • University of Alabama

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

• Sampling Method: Probability Sample

Study Population

Ophthalmology and Primary Care Clinics

Description

Inclusion Criteria:

• Men or women 18 years or older
• 39 type 1 or type 2 diabetic patients
• 13 with mild retinopathy
• 13 with moderate retinopathy
• 13 with severe, nonproliferative retinopathy
• 39 age and sex matched healthy controls

Exclusion Criteria:

• Current pregnancy as evidence by a urine pregnancy test as the blood from a pregnant female will influence the results of the laboratory tests

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Diabetic Patients; Mild, Moderate and Severe Retinopathy	Other: Diabetic Patients; measuring CD34 cell function in relation to diabetic retinopathy status
Healthy Controls; Age and sex matched Healthy Controls	Other: Healthy Controls; measuring CD34 cell function

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The ACE/ACE2 ratio within EPC's	Peripheral blood of 150cc, approximately 8-10 tablespoons will be collected from a vein in the arm of both diabetic and healthy control patients.	up to 216 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The balance of the RAS (renin-angiotensin system) within EPCs	The Endo-PAT2000 will be used to obtain this measurement. This is a 15-minute office-based test where a blood-pressure cuff is placed around the arm, inflated and measurements are obtained from a small fingertip monitor	up to 216 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Photography findings	The findings from eye photographs will be collected and evaluated from both the diabetic patients and the heallthy control patients. This will be done at either the patient's yearly visit or at their 6 week follow-up visit.	up to 216 weeks
Fluorescein angiogram findings	The findings from eye photographs will be collected and evaluated from both the diabetic patients and the heallthy control patients. This will be done at either the patient's yearly visit or at their 6 week follow-up visit.	up to 216 weeks

Collaborators and Investigators

• Sponsor: University of Alabama at Birmingham
• Collaborators: National Heart, Lung, and Blood Institute (NHLBI)
• Investigators: Principal Investigator: Maria B Grant, MD, University of Alabama at Birmingham

Study record dates

Study Major Dates

• Study Start (Actual): October 30, 2011
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: April 14, 2014
• First Submitted That Met QC Criteria: April 21, 2014
• First Posted (Estimated): April 22, 2014

Study Record Updates

• Last Update Posted (Estimated): December 23, 2025
• Last Update Submitted That Met QC Criteria: December 19, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Diabetes; Retinopathy
• Additional Relevant MeSH Terms: Endocrine System Diseases; Vascular Diseases; Cardiovascular Diseases; Metabolic Diseases; Glucose Metabolism Disorders; Eye Diseases; Diabetic Angiopathies; Diabetes Complications; Nutritional and Metabolic Diseases; Retinal Diseases; Diabetic Retinopathy; Diabetes Mellitus
• Other Study ID Numbers: 1308798827; R01HL110170 (U.S. NIH Grant/Contract)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No