Measurement of Glucose Metabolism in Humans Using Magnetic Resonance at 4 Tesla. Substudy: Hypoglycemia Unawareness
| Status: | Completed |
|---|---|
| Conditions: | Other Indications, Endocrine, Diabetes |
| Therapuetic Areas: | Endocrinology, Other |
| Healthy: | No |
| Age Range: | 18 - 65 |
| Updated: | 1/20/2018 |
| Start Date: | December 2007 |
| End Date: | March 2017 |
The purpose of this study is to determine whether islet transplantation alters brain glucose
concentrations in patients with type 1 diabetes, recurrent hypoglycemia, and hypoglycemia
unawareness when compared to that measured prior to transplant in the same subjects.
concentrations in patients with type 1 diabetes, recurrent hypoglycemia, and hypoglycemia
unawareness when compared to that measured prior to transplant in the same subjects.
Individuals with type 1 diabetes and hypoglycemia unawareness who become active islet
transplant candidates and matched controls will be recruited for participation in this study.
Subjects will undergo a hyperglycemic clamp with somatostatin before and 6 months after islet
transplantation. During the clamp study, their brain glucose concentrations will be measured
by proton magnetic resonance spectroscopy. Following these measurements, subjects will
undergo a hypoglycemic clamp study to assess their counterregulatory response.
On the morning of the study subjects will report to the Clinical Research Center in the CMRR
and be asked to do the following:
1. All subjects will be asked not to eat anything after midnight on the day before the
magnet study at the Magnet Center. A small plastic catheter will be placed in a vein in
each arm for infusion of hormones. A third plastic catheter will be placed in a foot
vein for measuring blood glucose levels. The foot and distal leg will be placed in a
heated blanket for the duration of the study to speed up the flow of blood through the
vein and for easy withdrawing of blood. During the study subjects will receive carefully
calculated doses of insulin, glucose, potassium phosphate, and somatostatin. These
substances will be contained in syringes or bags and pumped through intravenous
catheters placed in the arms. Insulin and somatostatin are hormones that are made
naturally by the body. Initially we will keep blood sugar at the normal level. The blood
glucose will then be raised by infusing glucose at a calculated rate. We will maintain
the high blood sugar concentration for 45 to 120 minutes. This causes no symptoms other
than a necessity f to pass urine more frequently than normal. The blood glucose infusion
will then be dropped to allow blood glucose to drop in small steps to the normal glucose
concentration. We will draw at most 15 oz. of blood during this part of the study.
2. All subjects will be asked to participate in a second experiment after the magnet study.
Subjects may chose to perform this part of the study at Yale University. If subjects
choose to stay at the University Of Minnesota, they will be participating in the second
experiment either the same day or the day after the first experiment. If done the same
day, the arm catheters will be left in place for infusion of insulin, potassium
phosphate, and glucose. A third catheter may be placed in the hand for venous blood
sampling. This hand will be placed in a warming box to ensure adequate blood flow and
accurate laboratory results. Blood will be drawn every 5 minutes for measurement of
glucose and other hormones. The total amount of blood drawn will be about 10
tablespoons. Insulin will be infused to lower blood sugar level to a level below the
normal range. It will be maintained at this low level for thirty minutes after which
time the insulin infusion will be discontinued and the blood sugar level allowed to
normalize. Subjects will then be given a meal.
3. Subjects with type 1 diabetes will be asked to spend the night before each study at the
General Clinical Research Center so that blood glucose values can be maintained between
80-110 mg/dl. They will be asked to hold insulin doses in the evening before and on the
morning of the study and insulin will be provided via an intravenous infusion. For those
subjects with diabetes who chose to undergo all testing at the University of Minnesota,
they will be followed as inpatients in the GCRC during one to two days of testing.
4. Following islet transplant subjects will be asked to undergo the magnet study described
under point #1 above and the hypoglycemia study described under point #3 above at
approximately 3-9 months after the procedure.
transplant candidates and matched controls will be recruited for participation in this study.
Subjects will undergo a hyperglycemic clamp with somatostatin before and 6 months after islet
transplantation. During the clamp study, their brain glucose concentrations will be measured
by proton magnetic resonance spectroscopy. Following these measurements, subjects will
undergo a hypoglycemic clamp study to assess their counterregulatory response.
On the morning of the study subjects will report to the Clinical Research Center in the CMRR
and be asked to do the following:
1. All subjects will be asked not to eat anything after midnight on the day before the
magnet study at the Magnet Center. A small plastic catheter will be placed in a vein in
each arm for infusion of hormones. A third plastic catheter will be placed in a foot
vein for measuring blood glucose levels. The foot and distal leg will be placed in a
heated blanket for the duration of the study to speed up the flow of blood through the
vein and for easy withdrawing of blood. During the study subjects will receive carefully
calculated doses of insulin, glucose, potassium phosphate, and somatostatin. These
substances will be contained in syringes or bags and pumped through intravenous
catheters placed in the arms. Insulin and somatostatin are hormones that are made
naturally by the body. Initially we will keep blood sugar at the normal level. The blood
glucose will then be raised by infusing glucose at a calculated rate. We will maintain
the high blood sugar concentration for 45 to 120 minutes. This causes no symptoms other
than a necessity f to pass urine more frequently than normal. The blood glucose infusion
will then be dropped to allow blood glucose to drop in small steps to the normal glucose
concentration. We will draw at most 15 oz. of blood during this part of the study.
2. All subjects will be asked to participate in a second experiment after the magnet study.
Subjects may chose to perform this part of the study at Yale University. If subjects
choose to stay at the University Of Minnesota, they will be participating in the second
experiment either the same day or the day after the first experiment. If done the same
day, the arm catheters will be left in place for infusion of insulin, potassium
phosphate, and glucose. A third catheter may be placed in the hand for venous blood
sampling. This hand will be placed in a warming box to ensure adequate blood flow and
accurate laboratory results. Blood will be drawn every 5 minutes for measurement of
glucose and other hormones. The total amount of blood drawn will be about 10
tablespoons. Insulin will be infused to lower blood sugar level to a level below the
normal range. It will be maintained at this low level for thirty minutes after which
time the insulin infusion will be discontinued and the blood sugar level allowed to
normalize. Subjects will then be given a meal.
3. Subjects with type 1 diabetes will be asked to spend the night before each study at the
General Clinical Research Center so that blood glucose values can be maintained between
80-110 mg/dl. They will be asked to hold insulin doses in the evening before and on the
morning of the study and insulin will be provided via an intravenous infusion. For those
subjects with diabetes who chose to undergo all testing at the University of Minnesota,
they will be followed as inpatients in the GCRC during one to two days of testing.
4. Following islet transplant subjects will be asked to undergo the magnet study described
under point #1 above and the hypoglycemia study described under point #3 above at
approximately 3-9 months after the procedure.
Inclusion Criteria:
- Age 18-65
- Must be able to provide informed consent
- Type 1 diabetes >5 years duration
- Healthy controls
Exclusion Criteria:
- Over 300 pounds
- Claustrophobic
- History of ischemic heart disease, arrhythmia or seizure disorder
- Pregnant
- On medications known to alter blood flow or carbohydrate metabolism
- Have internally located pieces of metal
We found this trial at
1
site
Minneapolis, Minnesota 55455
(612) 625-5000
Principal Investigator: Elizabeth R Seaquist, MD
Phone: 612-626-4833
Univ of Minnesota With a flagship campus in the heart of the Twin Cities, and...
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