Pioglitazone Incretin Study

Study Overview
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Brief Summary
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Incretin hormones are hormones produced by the gut in response to food intake. These hormones help the body to control the metabolism of glucose (sugar). In particular, two incretin hormones (GLP-1 and GIP) cause the pancreas to secrete more insulin in response to high blood glucose levels. This helps the body to metabolize the glucose more effectively, lowering blood sugar levels. GLP-1 and GIP do not work as well in patients with type 2 diabetes (T2DM) as in subjects who do not have diabetes. This study tests whether a medicine called pioglitazone (Actos), which is commonly used to treat T2DM, improves the ability of GIP to increase insulin secretion. To address this question the investigators will recruit patients with T2DM whose diabetes is controlled with either diet and exercise or with metformin (another medicine commonly used to treat T2DM). Subjects will undergo measurement of body fat by DEXA scanning and a series of studies to characterize their metabolism. These studies include an oral glucose tolerance test (a test sometimes used to diagnose diabetes), a mixed-meal challenge (to measure how much GLP-1 and GIP are produced in response to a meal) and measurement of insulin secretion in response to glucose and GIP given through a vein. The investigators will also obtain small samples of fat (from just under the skin of the belly) using a needle to measure levels of the receptor for GIP. Subjects will then be randomly assigned to 12 weeks of treatment with either pioglitazone or matching placebo (an inactive tablet that does not contain medication). The dose of pioglitazone will be increased during the first 4 weeks to the maximum prescribed dose of 45 mg per day. Subjects will be seen every 2-4 weeks during the treatment phase of the study. After 12 weeks of treatment all studies performed at the beginning of the study will be repeated. The pioglitazone treatment will continue until the end of testing, approximately 4 weeks. The results of this study may give us information about why glucose control deteriorates in T2DM. This information might also lead to new ways to prevent or treat T2DM.

Official Title
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Effects of Pioglitazone on the Regulation of Insulin Secretion in Patients With Type 2 Diabetes

Conditions
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Diabetes Mellitus, Type 2

Intervention / Treatment
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* Drug: Pioglitazone
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Type 2 diabetes controlled with diet+exercise or metformin monotherapy HbA1c less than or equal to 7% Women will be non-fertile or practicing birth control Exclusion Criteria: Acute or chronic medical conditions that would contraindicate participation Class III or IV heart failure Pregnant or nursing women Patients taking antidiabetic medications other than metformin, oral or chronic topical steroids, weight loss agents, antipsychotics, or other drugs that could affect insulin sensitivity or secretion. AST or ALT more than 2.5 times the upper limit of normal Active alcohol or drug abuse Weight greater than 300 pounds

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: 1<br>Pioglitazone arm | Drug: Pioglitazone<br>* Starting dose at 15 mg for two weeks, then titrated up to 45 mg in the subsequent 2 weeks.<br>* Other names: Actos (brand name for pioglitazone);|
| Placebo Comparator: 2<br>Placebo arm | Drug: Placebo<br>* placebo<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in incretin-mediated insulin secretion and receptor regulation of glucose-dependent insulinotropic peptide (GIP) in patients with type 2 diabetes. |  | 12 weeks per subject | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in active GIP in response to an oral glucose tolerance test and mixed meal challenge |  | 12 weeks | 
| Change in active GLP-1 in response to the oral glucose tolerance test and the mixed meal challenge |  | 12 weeks | 
| Change in glucose response during the oral glucose tolerance test and mixed meal challenge |  | 12 weeks | 
| Change in insulin secretion during the oral glucose tolerance test and the mixed meal challenge |  | 12 weeks | 
| Change in the acute insulin response to glucose, insulin sensitivity and the disposition index during the IV glucose tolerance test. |  | 12 weeks | 
| Change in adipocyte GIP receptor mRNA expression levels. |  | 12 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Diabetes, pioglitazone, GIP