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

Lane JT, Larson L, Fan S, Stoner JA, Margalit E, Toris CB - BMC Ophthalmol (2010)

Bottom Line: Ocular pulse amplitude and outflow facility were not different between groups.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5840, USA. jtlane1@unmc.edu

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 microl/min in the diabetes group compared to controls (2.58 +/- 0.65 versus 3.16 +/- 0.66 microl/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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Glucose and insulin concentrations (mean ± SD) over time during the hyperinsulinemic-euglycemic glucose clamp in patients with type 1 diabetes and age-matched healthy controls (n = 10).
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Figure 1: Glucose and insulin concentrations (mean ± SD) over time during the hyperinsulinemic-euglycemic glucose clamp in patients with type 1 diabetes and age-matched healthy controls (n = 10).

Mentions: The insulin and glucose levels during the euglycemic-hyperinsulinemic glucose clamp are summarized in Figure 1. At baseline, mean total insulin levels were significantly greater for patients with diabetes, compared to controls (p < 0.001). Within one hour, insulin concentrations were similar between groups and remained that way for the remaining 3.5 hours. Insulin concentrations during the last hour of the clamp were similar (174.1 ± 30.6 mU/ml in patients versus 166.8 ± 33.9 mU/ml in controls, p = 0.6). Glucose concentrations at the beginning of the clamp were higher in patients with type 1 diabetes, compared to controls. By 80 minutes into the clamp the glucose levels were similar between groups and remained similar for the rest of the clamp. The whole body glucose infusion rate during the last 30 minutes of the clamp, an indication of insulin sensitivity, was lower in patients with type 1 diabetes, compared to controls (7.6 ± 3.7, versus 11.7 ± 2.9 mg/kg/min, respectively, p = 0.01).


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

Lane JT, Larson L, Fan S, Stoner JA, Margalit E, Toris CB - BMC Ophthalmol (2010)

Glucose and insulin concentrations (mean ± SD) over time during the hyperinsulinemic-euglycemic glucose clamp in patients with type 1 diabetes and age-matched healthy controls (n = 10).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2908568&req=5

Figure 1: Glucose and insulin concentrations (mean ± SD) over time during the hyperinsulinemic-euglycemic glucose clamp in patients with type 1 diabetes and age-matched healthy controls (n = 10).
Mentions: The insulin and glucose levels during the euglycemic-hyperinsulinemic glucose clamp are summarized in Figure 1. At baseline, mean total insulin levels were significantly greater for patients with diabetes, compared to controls (p < 0.001). Within one hour, insulin concentrations were similar between groups and remained that way for the remaining 3.5 hours. Insulin concentrations during the last hour of the clamp were similar (174.1 ± 30.6 mU/ml in patients versus 166.8 ± 33.9 mU/ml in controls, p = 0.6). Glucose concentrations at the beginning of the clamp were higher in patients with type 1 diabetes, compared to controls. By 80 minutes into the clamp the glucose levels were similar between groups and remained similar for the rest of the clamp. The whole body glucose infusion rate during the last 30 minutes of the clamp, an indication of insulin sensitivity, was lower in patients with type 1 diabetes, compared to controls (7.6 ± 3.7, versus 11.7 ± 2.9 mg/kg/min, respectively, p = 0.01).

Bottom Line: Ocular pulse amplitude and outflow facility were not different between groups.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5840, USA. jtlane1@unmc.edu

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 microl/min in the diabetes group compared to controls (2.58 +/- 0.65 versus 3.16 +/- 0.66 microl/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.

Show MeSH
Related in: MedlinePlus