Intraocular pressure and aqueous humor flow during a euglycemic- hyperinsulinemic clamp in patients with type 1 diabetes and microvascular complications

James T. Lane, LuAnn Larson, Shan Fan, Julie A. Stoner, Eyal Margalit, Carol B Toris

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Background. Microvascular complications, including retinopathy and nephropathy are seen with type 1 diabetes. It is unknown whether functional changes in aqueous humor flow or intraocular pressure (IOP) develop in parallel with these complications. This study was designed to test the hypothesis that clinical markers of microvascular complications coexist with the alteration in aqueous humor flow and IOP. Methods. Ten patients with type 1 diabetes and ten healthy age- and weight-matched controls were studied. Aqueous flow was measured by fluorophotometry during a hyperinsulinemic-euglycemic clamp (insulin 2 mU/kg/min). Intraocular pressure was measured by tonometry at -10, 90 and 240 minutes from the start of the clamp, and outflow facility was measured by tonography at 240 minutes. Results. During conditions of identical glucose and insulin concentrations, mean aqueous flow was lower by 0.58 μ/min in the diabetes group compared to controls (2.58 ± 0.65 versus 3.16 ± 0.66 μ/min, respectively, mean ± SD, p = 0.07) but statistical significance was not reached. Before the clamp, IOP was higher in the diabetes group (22.6 ± 3.0 mm Hg) than in the control group (19.3 ± 1.8 mm Hg, p = 0.01) but at 90 minutes into the clamp, and for the remainder of the study, IOP was reduced in the diabetes group to the level of the control group. Ocular pulse amplitude and outflow facility were not different between groups. Systolic blood pressure was significantly higher in the diabetes group, but diastolic and mean arterial pressures were not different. Conclusions. We conclude that compared to healthy participants, patients with type 1 diabetes having microalbuminuria and retinopathy have higher IOPs that are normalized by hyperinsulinemia. During the clamp, a reduction in aqueous flow was not statistically significant.

Original languageEnglish (US)
Article number19
JournalBMC Ophthalmology
Volume10
Issue number1
DOIs
StatePublished - Jun 25 2010

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Glucose Clamp Technique
Aqueous Humor
Diabetes Complications
Intraocular Pressure
Type 1 Diabetes Mellitus
Fluorophotometry
Insulin
Blood Pressure
Control Groups
Manometry
Hyperinsulinism
Healthy Volunteers
Arterial Pressure
Biomarkers
Weights and Measures
Glucose

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Intraocular pressure and aqueous humor flow during a euglycemic- hyperinsulinemic clamp in patients with type 1 diabetes and microvascular complications. / Lane, James T.; Larson, LuAnn; Fan, Shan; Stoner, Julie A.; Margalit, Eyal; Toris, Carol B.

In: BMC Ophthalmology, Vol. 10, No. 1, 19, 25.06.2010.

Research output: Contribution to journalArticle

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abstract = "Background. Microvascular complications, including retinopathy and nephropathy are seen with type 1 diabetes. It is unknown whether functional changes in aqueous humor flow or intraocular pressure (IOP) develop in parallel with these complications. This study was designed to test the hypothesis that clinical markers of microvascular complications coexist with the alteration in aqueous humor flow and IOP. Methods. Ten patients with type 1 diabetes and ten healthy age- and weight-matched controls were studied. Aqueous flow was measured by fluorophotometry during a hyperinsulinemic-euglycemic clamp (insulin 2 mU/kg/min). Intraocular pressure was measured by tonometry at -10, 90 and 240 minutes from the start of the clamp, and outflow facility was measured by tonography at 240 minutes. Results. During conditions of identical glucose and insulin concentrations, mean aqueous flow was lower by 0.58 μ/min in the diabetes group compared to controls (2.58 ± 0.65 versus 3.16 ± 0.66 μ/min, respectively, mean ± SD, p = 0.07) but statistical significance was not reached. Before the clamp, IOP was higher in the diabetes group (22.6 ± 3.0 mm Hg) than in the control group (19.3 ± 1.8 mm Hg, p = 0.01) but at 90 minutes into the clamp, and for the remainder of the study, IOP was reduced in the diabetes group to the level of the control group. Ocular pulse amplitude and outflow facility were not different between groups. Systolic blood pressure was significantly higher in the diabetes group, but diastolic and mean arterial pressures were not different. Conclusions. We conclude that compared to healthy participants, patients with type 1 diabetes having microalbuminuria and retinopathy have higher IOPs that are normalized by hyperinsulinemia. During the clamp, a reduction in aqueous flow was not statistically significant.",
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