Diabetes, Orthostatic Hypotension, Syncope
Conditions
Keywords
Diabetes, Insulin, Orthostatic Hypotension, Falls, Syncope
Brief summary
In the proposed study, the investigators examine in older adults with Type 2 diabetes the impact of beginning insulin therapy on the orthostatic drop in blood pressure as well as the response of arterial blood pressure and Doppler measures of cerebral blood flow during upright tilt. The investigators hypothesize that in older adults with Type 2 diabetes, the cardiovascular effects of insulin would precipitate or worsen orthostatic intolerance not present at baseline.
Detailed description
Before and 2 weeks after the start of standard insulin therapy several tests will be done: * orthostatic hypotension will be tested for with 3 orthostatic maneuvers * vasovagal syncope will be tested with 2 tilt table tests, one augmented with 400ug of nitroglycerin * MCA velocity will be measured with a transcranial doppler * Heart Rate and Blood Pressure will be measured throughout the test with a Finometer and Power Lab on a beat to beat basis
Interventions
OTHERInsulin
Initiation of insulin administration will be determined as part of standard of care by the subjects diabetologist in the VGH Diabetes Centre and not as part of participation in this study.
OTHERNo Insulin
Study session will occur prior to initiation of insulin therapy.
Sponsors
University of British Columbia
Study design
Allocation
NON_RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
65 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* All subjects must be 65 years of age or older * All must have been diagnosed with Type 2 diabetes for at least 5 years * All subjects must be insulin-naïve on recruitment * All subjects must be eligible to start insulin therapy (long or intermediate acting) as determined by their diabetologist
Exclusion criteria
* Anemia, as determined by serum hematocrit * Abnormal liver function tests * Elevated creatinine * Smoker * Musculoskeletal or neurological condition that would preclude tilt table testing or orthostatic vitals
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 1. Presence or absence of orthostatic hypotension | 1 day | defined as a drop in systolic blood pressure greater than 20 mmHg after 3 minutes upright standing |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| 1. The nadir of middle cerebral artery (MCA) velocity | 1 day | lowest middle cerebral artery flow velocity determined by transcranial Doppler |
| 2. The presence or absence of a positive augmented tilt table test | 1 day | The augmented tilt table test will occur after receiving 300 μg nitroglycerin (GTN), and is a recognized method of testing for risk of vasovagal syncope. The tilt table will be considered positive and aborted prior to the 20 minutes if the subjects have a syncopal spell or demonstrate presyncopal (lightheadedness) symptoms in association with a 30 mm Hg drop in systolic blood pressure. |
| 3. The nadir of systolic blood pressure (SBP) and diastolic blood pressure (DBP) during tilt table test. | 1 day | lowest systolic blood pressure and diastolic blood pressure during tilt table tests and when they occur. |
Countries
Canada
Outcome results
None listed