Growth Hormone Feedback to Insulin-like Growth Factor-I (IGF-1) and Oral Glucose Tolerance Test (OGTT)
Completed · Not applicable · Has a placebo group
Conditions studied: Acromegaly, Type 2 Diabetes Mellitus
In brief
Growth hormone (GH) and Insulin-like growth factor-I (IGF-I) secretion are altered in acromegaly and type 2 Diabetes Mellitis (DM). The secretion of GH is mediated by central hypothalamic hormones (GH Releasing Hormone and somatostatin) as well as peripheral factors providing feedback inhibition (IGF-I and glucose, among others). The purpose of this study is to compare growth hormone suppression after an oral glucose tolerance test (OGTT) to growth hormone suppression after recombinant human IGF-I (rhIGF-I) administration. This study will recruit participants with active acromegaly, type 2 diabetes mellitus, and healthy control subjects. Each participant will undergo a screening evaluation, and three subsequent visits. Each participant will receive a placebo subcutaneous injection, OGTT, and administration of rhIGF-I, on separate visit days. Glucose, insulin, GH, bioactive IGF-I and IGF-I binding proteins will be measured after each intervention. Results will be compared between the three groups. It is predicted that the administration of rhIGF-I will demonstrate GH suppression in all healthy subjects and subjects with type 2DM. Some acromegaly subjects may demonstrate GH suppression in response to IGF-I administration, but not to the degree seen in healthy subjects or type 2 DM. OGTT will demonstrate suppression of GH in normal subjects, and will show attenuated suppression in type 2 DM and a failure of suppression in acromegaly.
Key facts
- Study ID
- NCT00915954
- Run by
- Cedars-Sinai Medical Center
- People needed
- 28
- Starts
- 2008-12-01
- Expected to finish
- 2014-06-01
- Last updated by the study team
- 2019-07-09
Who can join
Age: 18 and older. Sex: any. Healthy volunteers: accepted.
You may qualify if…
- Active acromegaly due to excess GH produced by a pituitary adenoma.
- Patients must have an elevated IGF-I compared to age and gender matched controls (as supplied by the laboratory) and fail to suppress GH to below 1 ng/ml after a standard 75g oral glucose tolerance test.
- Type 2 diabetes mellitus, defined by elevated fasting glucose ≥ 126 mg/dl (verified by two historical measurements), or plasma glucose ≥ 200 mg/dl two hours after a 75 g oral glucose load, or a random glucose ≥ 200 mg/dl.
You may not qualify if…
- Acromegaly Group
- Current medical therapy for acromegaly including dopamine agonists, somatostatin analogues, or growth hormone antagonists.
- For subjects on current therapy the following washout periods may be used:
- Cabergoline: 4 weeks
- Bromocriptine: 1 week
- Sandostatin LAR: 3 months
- Short-acting octreotide: 1 week
- Lanreotide: 3 months
- Pegvisomant: 4 weeks
- Subjects with a history of surgical therapy for treatment of acromegaly must have verification of active disease with verified elevated IGF-I for the subjects' age and gender compared to healthy controls (as supplied by the laboratory) (two measures) as well as a failure to suppress GH to below 1 ng/ml after OGTT.
- Current treatment for insulin resistance or type 2 DM including oral or injection medications.
- Fasting glucose ≥ 126 mg/dl at screening evaluation.
- Evidence of hepatic or renal disease defined as elevated transaminases, elevated serum creatinine.
- Pregnancy or breast feeding.
- Type 2 diabetes mellitus group
- Patients taking non-insulin medications for diabetes treatment will be excluded.
- Diagnosis of acromegaly.
- Evidence of hepatic or renal disease defined as elevated transaminases, elevated serum creatinine.
- Pregnancy or breast feeding.
- Healthy Control Group
- History of diabetes mellitus or impaired glucose tolerance, history of acromegaly.
- Fasting glucose ≥ 126 mg/dl at screening evaluation.
- Evidence of hepatic or renal disease defined as elevated transaminases, elevated serum creatinine.
- Pregnancy or breast feeding.
Where it is running
- Cedars-Sinai Medical Center Pituitary Center — Los Angeles, California, United States
Full record on ClinicalTrials.gov
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