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Growth Hormone Feedback to Insulin-like Growth Factor-I (IGF-1) and Oral Glucose Tolerance Test (OGTT)

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified July 2009 by Cedars-Sinai Medical Center.
Recruitment status was:  Recruiting
Information provided by:
Cedars-Sinai Medical Center Identifier:
First received: June 5, 2009
Last updated: July 28, 2009
Last verified: July 2009
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.

Condition Intervention Phase
Type 2 Diabetes Mellitus
Other: oral glucose tolerance test
Other: Subcutaneous administration of recombinant human IGF-1
Phase 4

Study Type: Interventional
Study Design: Masking: Single Blind (Participant)
Official Title: Growth Hormone Feedback In Patients With Acromegaly, Type 2 Diabetes Mellitus, And Healthy Adults

Resource links provided by NLM:

Further study details as provided by Cedars-Sinai Medical Center:

Primary Outcome Measures:
  • Growth hormone nadir, defined as the lowest measured growth hormone after administration of a suppressive agent (oral glucose or rhIGF-I)

Secondary Outcome Measures:
  • Changes in IGFBP-1, insulin, glucose, bioactive IGF-I after administration of placebo, OGTT and rhIGF-I

Estimated Enrollment: 30
Study Start Date: December 2008
Intervention Details:
    Other: oral glucose tolerance test
    Participants will have their blood drawn for a baseline value and then will be asked to drink a beverage with 75 grams of sugar. Blood will then be drawn every 30 minutes for 2 hours.
    Other: Subcutaneous administration of recombinant human IGF-1
    Participants will receive a subcutaneous injection of recombinant human IGF-1 followed by a series of blood draws.

Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • 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.

Exclusion Criteria:

  1. 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.
  2. 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.
  3. 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.
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Please refer to this study by its identifier: NCT00915954

Contact: William Gellepis 310-423-3395
Contact: Lori Korsakoff, RN 310-423-2411

United States, California
Cedars-Sinai Medical Center Pituitary Center Recruiting
Los Angeles, California, United States, 90048
Principal Investigator: John Carmichael, MD         
Sponsors and Collaborators
Cedars-Sinai Medical Center
  More Information Identifier: NCT00915954     History of Changes
Other Study ID Numbers: 17015
Study First Received: June 5, 2009
Last Updated: July 28, 2009

Keywords provided by Cedars-Sinai Medical Center:
Type 2 diabetes mellitus
recombinant human IGF1
oral glucose tolerance test

Additional relevant MeSH terms:
Diabetes Mellitus
Diabetes Mellitus, Type 2
Glucose Metabolism Disorders
Metabolic Diseases
Endocrine System Diseases
Bone Diseases, Endocrine
Bone Diseases
Musculoskeletal Diseases
Pituitary Diseases
Hypothalamic Diseases
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases
Hormones, Hormone Substitutes, and Hormone Antagonists
Physiological Effects of Drugs processed this record on May 25, 2017