Effect of Pioglitazone and Exenatide on Body Weight and Beta Cell Function

Phase 4

Completed

Conditions: Healthy
Impaired Glucose Tolerance
Type 2 Diabetes

Interventions: Drug: Pioglitazone
Drug: Exenatide
Drug: Pioglitazone and Exenatide

Registration Number: NCT00845182

Lead Sponsor: The University of Texas Health Science Center at San Antonio

Brief Summary: Pioglitazone, a drug used in treatment of type 2 diabetes has been shown to improve insulin sensitivity in skeletal muscle, liver, and fat cells. Despite the beneficial effects of pioglitazone to improve insulin sensitivity and reduce cardiovascular disease in high risk type 2 diabetic patients, weight gain has been a limiting factor. Exenatide, another agent used for treatment of T2DM, improves glycemic control and promotes moderate weight loss. In this proposal we will examine the effect of combination therapy with pioglitazone plus exenatide on body weight, fat topography, beta cell function, glycemic control, and plasma lipid levels in subjects with type 2 diabetes mellitus compared to treatment with each drug separately. Assessment of beta cell function will be performed by measuring the maximal insulin secretory capacity using a maximal hyperglycemic stimulus combined with an intravenous arginine stimulus.

Detailed Description: The thiazolidinedione (TZD) class of drugs has been shown to improve insulin sensitivity in skeletal muscle, liver, and adipocytes and to have anti-inflammatory and cardioprotective effects. The beta cell function, measured by the insulin secretion/insulin resistance index during the OGTT, improves significantly. In the present study, we will perform a more definitive assessment of beta cell function in TZD-treated diabetic patients by measuring the maximal insulin secretory capacity using a maximal hyperglycemic stimulus combined with an intravenous arginine stimulus.

Despite the beneficial effects of pioglitazone to improve insulin sensitivity and reduce cardiovascular events in high risk type 2 diabetic patients, weight gain has been a limiting factor for primary care physicians even though pioglitazone treatment leads to a redistribution of fat out of muscle/liver/visceral area to subcutaneous fat.

Exenatide (Byetta) is 39 amino acid peptide which exhibits biological actions similar to GLP-1. In clinical trials exenatide reduces HbA1c by 1-1.2% in subjects with type 2 diabetes and promotes moderate weight loss which is sustained for up to 2 years.

In this proposal we will examine the effect of combination therapy with pioglitazone plus exenatide on body weight, fat topography, beta cell function, glycemic control, and plasma lipid levels in subjects with type 2 diabetes mellitus compared to monotherapy with each agent separately. We postulate that combination therapy will result in significant weight loss (in contrast to the weight gain which accompanies pioglitazone treatment) and have an additive, or even synergistic, effect to improve beta cell function and glycemic control in type 2 diabetic patients who are inadequately controlled on oral agent therapy with metformin alone, a sulfonylurea alone, or combination of metformin plus a sulfonylurea. We will also compare the insulin secretion in healthy control subjects (NGT, n=15) and subjects with impaired glucose tolerance (IGT, n=15) to evaluate the relative decline in beta cell function in T2DM compared to NGT and IGT subjects. NGT and IGT subjects will participate only in a OGTT and a Hyperglycemic clamp- they will not receive any medication.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 43

Inclusion Criteria

Diabetic patients must be on diet therapy alone or diet plus a sulfonylurea, or diet plus metformin, or diet plus sulfonylurea/metformin and have a HbA1c ≥ 7.0%.
Patients must have the following laboratory values:

Hematocrit ≥ 34 vol% Serum creatinine ≤ 1.8 mg/dl AST (SGOT) ≤ 2 times upper limit of normal ALT (SGPT) ≤ 2 times upper limit of normal Alkaline phosphatase ≤ 2 times upper limit of normal
Patients must have been on a stable dose of allowed chronic medications for 30 days prior to entering the study.
Body weight must be stable (± 3-4 pounds) over the three months prior to study
The normal healthy control group will be age, weight (BMI), and gender matched with the diabetic group and must have a normal OGTT according to ADA criteria.
Subjects with IFG/IGT will have a FPG (100-125mg/dl) and/or 2-h plasma glucose (140-199mg/dl) according to ADA criteria.

Exclusion Criteria

Patients must not have type 1 diabetes.
Patients must not have a fasting plasma glucose of greater than 270 mg/dl or HbA1c > 10.0%.
Patients must not have received a thiazolidinedione or insulin for more than one week during the year prior to randomization.
Patients with a history of clinically significant heart disease (New York Heart Classification greater than class 2.

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Pioglitazone	Pioglitazone	Pioglitazone: 15 Patients will be randomized to Pioglitazone only arm
Exenatide	Exenatide	Exenatide: 15 subjects will be randomized to receive Exenatide
Drug Pioglitazone and Drug Exentatide	Pioglitazone and Exenatide	Pioglitazone and Exenatide: 15 subjects will be randomized to Pioglitazone and Exenatide

Primary Outcome Measures

Name	Time	Method
HbA1c	baseline and 6 months	change in HbA1c was measured before and after treatment in three groups
Effect of Pioglitazone, Exenatide and Combined Pioglitazone and Exenatide on Body Weight	baseline and 6 months	Effect of Pioglitazone, Exenatide and combined Pioglitazone and Exenatide on body weight and beta cell function

Secondary Outcome Measures

Name	Time	Method
Effect Pioglitazone, Exenatide, and Pioglitazone Plus Exenatide • Insulin Sensitivity • Inflammatory Cytokines • Glucagon and Free Fatty Acids • Plasma Lipids	6 months	Effect pioglitazone, exenatide, and pioglitazone plus exenatide on * Insulin sensitivity * Inflammatory cytokines * glucagon and free fatty acids * plasma lipids measured over a 6 month period