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Abstract #18506 Published in IGR 3-3
Acute effects of insulin on aqueous humor flow in patients with type 1 diabetes
Lane JT; Toris CB; Nakhle SN; Chacko DM; Wang YL; Yablonski MEAmerican Journal of Ophthalmology 2001; 132: 321-327
PURPOSE: Previous studies reported reduced aqueous humor flow through the anterior segment of the eye in patients with type 1 diabetes. This study investigates whether reduced flow is the result of the diabetic state or of alterations in glucose or insulin concentrations. METHODS: A cross-sectional study, involving patients with type 1 diabetes and healthy controls, measured aqueous flow at different insulin concentrations. Eleven patients with type 1 diabetes (hemoglobin A1C = 7.0 ± 0.3% (mean ± SEM), normal < 6.5) with no microvascular complications and 17 controls were prospectively studied. Controls were studied fasting and during a hyperinsulinemic-euglycemic clamp (insulin 2 mU/kg per minute). Patients with type 1 diabetes were similarly studied during two euglycemic clamp procedures (insulin 0.5 and 2.0 mU/kg per minute). Aqueous flow was measured by fluorophotometry. Pulsatile ocular blood flow and intraocular pressure (IOP) were measured with a Langham flow probe. RESULTS: Control subjects had no change in aqueous flow during fasting and hyperinsulinemic conditions (3.0 ± 0.1 versus 2.8 ± 0.1 μl per minute). In the patients with type 1 diabetes, aqueous flow was not decreased with hyperinsulinemia, compared with the low insulin state (p = 0.7). Compared with control subjects, patients with type 1 diabetes had lower aqueous flow during hyperinsulinemia (2.4 ± 0.1 μl per minute, p = 0.03) and at lower insulin conditions (2.6 ± 0.1 μl per minute, p < 0.05). No differences in IOP or pulsatile ocular blood were noted between groups or between insulin states within groups. CONCLUSIONS: Aqueous flow is decreased in patients with type 1 diabetes under euglycemic conditions of high and relatively low insulin concentrations, despite the absence of microvascular complications.
Dr J.T. Lane, Department of Internal Medicine, Section of Diabetes, Endocrinology, and Metabolism, University of Nebraska Medical Center, 983020 Nebraska Medical Center, Omaha, NE 68198-3020, USA. jtlanel@unmc.edu
Classification:
2.6 Aqueous humor dynamics (Part of: 2 Anatomical structures in glaucoma)