Corneal Nerves Function and Structure

Completed · Not applicable

Conditions studied: Diabetic Peripheral Neuropathy

In brief

Peripheral neuropathy affects about 50% of the diabetic population and there is no treatment other than good blood glucose control, which is ineffective in subjects with type 2 diabetes. Part of the problem for the lack of an effective treatment is the inability to detect peripheral neuropathy in its early stage. The hypotheses to be addressed in the first phase of this study is that changes in cornea sensitivity (blinking and squinting) following addition of a hyperosmotic solution will provide a novel screening tool for early diagnosis of peripheral neuropathy. For the second phase of the study the investigators will examine the effect of fish oil treatment of diabetic subjects with neuropathy on corneal nerve density and sensitivity. Corneal nerves are the most highly innervated part of the human body with great sensitivity. The first phase will use this property and determine whether sensitivity is lost in diabetic patients with neuropathy. Preclinical studies have supported this hypothesis and now this will be tested in human subjects. Preclinical studies have also shown that treating diabetic rodents with fish oil improves nerve regeneration and outcome measures of peripheral in diabetic rodents. In the second phase the investigators will perform preliminary studies in human subjects with diabetic neuropathy and determine whether treating them with fish oil increases corneal nerve density and sensitivity.

Key facts

Study ID: NCT04222660
Run by: VA Office of Research and Development
People needed: 44
Starts: 2021-06-21
Expected to finish: 2025-05-13
Last updated by the study team: 2025-05-23

Who can join

Age: 50 and older, up to 75. Sex: any. Healthy volunteers: accepted.

You may qualify if…

Type 2 diabetes patients diagnosed based on the opinion of an Endocrinologist (Dr. Correia), the absence of a history of ketoacidosis, and a C-peptide > 0.8 ng/ml
At least 5 year known duration of diabetes.
HbA1c < 9.0%
None or mild to moderate peripheral neuropathy based on medical record, Michigan Neuropathy Screening Instrument including response to monofilament test, ankle reflex test, vibration perception threshold examination using a 128 Hz tuning fork as well as hot and cold sensation evaluation

You may not qualify if…

Any neurologic, muscular, genetic, or other condition known to affect nerve or muscle function
Electrolyte abnormalities, untreated hypothyroidism, abnormalities in calcium, phosphate, or magnesium concentrations, or any other metabolic disturbance affecting neural function
Cigarette smoking in the past year
Peripheral vascular, cardiac, pulmonary, or any other disorder affecting blood or tissue oxygenation
Risk of bleeding disorder or on medication known to increase risk of bleeding
History for use of aspirin
Any other medical or psychological condition judged to limit compliance with the protocol or interpretation of results
History of diabetic foot ulcer
LDL > 100 mg/100ml, HDL < 30 mg/100ml, Triglyceride > 400 mg/100ml.* 10) BP < 140 systolic and 80 diastolic
BMI 45
Insulin use to manage diabetes 200 units
History of taking fish oil supplements
The investigators are limiting subject population to those over 50 thus pregnancy should not be an issue nonetheless females who are pregnant, looking to become pregnant or are breast feeding will be excluded (* After overnight fast of 8-12 h; Average of three determinations in the sitting position after at least 5 minutes rest.)

Where it is running

Iowa City VA Health Care System, Iowa City, IA — Iowa City, Iowa, United States

Full record on ClinicalTrials.gov

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