Conditions: Type 2 Diabetes Mellitus
Keywords: diabetes, blood flow, brain perfusion, cognitive function
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 30
Healthy volunteers: yes

Brief summary:
Our goal is to determine the acute effects of intranasal insulin on regional perfusion and cognition of older adults. We propose a pilot study to examine the effect of a single dose of intranasal insulin on regional vasoreactivity and cognitive functions in 30 subjects with T2DM and 30 healthy controls \>50 years old using a double blinded, placebo-controlled, cross-over design.

Hypothesis 1: Intranasal insulin improves acutely regional perfusion and vasoreactivity in older patients with T2DM as compared with placebo and compared with the control group.

Hypothesis 2: Intranasal insulin improves cognitive functioning including attention, memory and executive function in diabetic patients as compared with placebo and compared with control group.

Detailed description:
Type 2 diabetes mellitus (T2DM) is a major risk factor for vascular dementia. DM alters insulin transport across blood-brain barrier affecting perfusion and neuronal function. Intranasal administration enables effective delivery of insulin to the brain. Clinical studies demonstrated improvement of cognitive function and memory in healthy and cognitively impaired people.

Aim 1: To determine the acute effects of a single 40-IU dose of intranasal insulin vs. placebo on regional perfusion and vasoreactivity to CO2 challenge measured by 3-D continuous arterial spin labeling (CASL) MRI at 3 Tesla in the control and diabetic groups. We will use transcranial Doppler to determine the effects on intranasal insulin vs. placebo on cerebral autoregulation based on measurements of beat-to-beat pressure flow velocity relationship.

Aim 2: To determine whether intranasal insulin improves cognitive functioning in older T2DM patients as compared with placebo and the control group.

This translational study will address an important area about the effects of intranasal insulin on cerebral blood flow regulation and cognition in older diabetics that has not been studied. Intranasal insulin administration may provide a novel therapeutic target for prevention and treatment of microvascular disease and cerebrovascular complications of T2DM. If successful, this approach may have significant impact on the clinical management of large population of older adults with T2DM.

Arms:
arm 1: Comparisons of acute effects of intranasal insulin or placebo (saline) on cerebral blood flow and cognition in healthy controls and type 2 diabetes. arm 2: Comparisons of acute effects of intranasal insulin or placebo (saline) on cerebral blood flow and cognition in healthy controls and type 2 diabetes.

Interventions: intervention 1: Intranasal insulin intervention 2: Placebo
Intervention descriptions: intervention 1: The acute effects of a single 40-IU dose of intranasal insulin intervention 2: The acute effects of intranasal sterile saline.

Protocol document: