Jonathan Krakoff, M.D.

Clinical Trials

Open studies conducted by NIDDK Principal Investigators appear below. Study statuses may include the following:

  • Open: Recruiting - Currently recruiting participants and open to everyone who meets eligibility criteria.
  • Open: Active, Not Recruiting - Participants are receiving an intervention or being examined, however new participants are not being recruited or enrolled.
  • Open: Enrolling by Invitation - People in a particular population were selected in advance and invited to participate. The study is not open to everyone who meets the eligibility criteria.
  • Open: Available for Expanded Access - Patients who are not participants in the clinical study may be able to gain access to the drug, biologic, or medical device being studied.

Studies Seeking Patients

A Comparative Effectiveness Study of Major Glycemia-lowering Medications for Treatment of Type 2 Diabetes

The GRADE Study is a pragmatic, unmasked clinical trial that will compare commonly used diabetes medications, when combined with metformin, on glycemia-lowering effectiveness and patient-centered outcomes.

The trial is Open with a status of Active, not recruiting.

Investigator: David M Nathan, MD

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Effects of Brain Stimulation on Food Intake and Behavioral Weight Loss Treatment

This study will determine whether electrical stimulation of an area of the brain called the dorsolateral prefrontal cortex, which is important in determining the feeling of fullness after eating, affects how much food a person eats and weight loss over 4 weeks. It will also compare weight changes in people who attend weight loss counseling sessions and those who do not over this period of time. Obese, non-diabetic people between 18 and 60 years of age who are in good health and who live in the Phoenix, AZ, metropolitan area are eligible for this study. Candidates must have a body mass index of 35 kg/m(2) or more and weigh less than 350 pounds. Participants are admitted to the NIH inpatient unit in Phoenix for the first 9 days of the study for tests, which include meal tests to determine eating behaviors and caloric intake, blood and urine tests, glucose tolerance test, weight measurement, psychological assessments and DEXA scan to measure body fat. For 3 of the days, they will be asked to eat all of their food from automated vending machines. Some subjects receive transcranial direct current stimulation (TDCS). For this procedure, electrodes that conduct electricity are placed on the head and arm and the current is turned on for 40 minutes. Some tingling may be felt under the electrodes. Other subjects receive sham TDCS, with the current turned on only very briefly. After the evaluations, subjects are discharged home from the NIH unit and instructed to eat 25 percent fewer calories than they consumed while on a weight maintenance diet the first 3 days of their inpatient stay. They maintain the lower calorie diet at home for 4 weeks. During this period they come to the NIH unit 3 days a week to receive either real or sham TDCS. ...

The trial is Open with a status of Recruiting.

Investigator: Marci Gluck, Ph.D.

Referral Contacts: Email: Marci Gluck, Ph.D. Phone: (602) 200-5312

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Effects of Diet Changes on Metabolism

This study, conducted at the NIH Clinical Research Unit at the Phoenix Indian Medical Center, will examine how the body s metabolism (energy expenditure) changes when people overeat and when they fast and how different diets (e.g., high-protein or high-fat) affect metabolism. The results may provide information about whether there are mechanisms that make some people more resistant than others to gaining weight when they eat more. Non-smoking healthy subjects between 18 and 55 years of age who weigh no more than 350 pounds may be eligible for this study. Participants undergo the following procedures: - Pregnancy test for women of childbearing age. - Oral glucose tolerance test. For this test, an I.V. line (needle attached to a plastic tube) is inserted into a vein to allow several blood draws without repeated needle sticks. After the first blood sample is drawn, the subject drinks a cola-flavored sugar solution. Five additional blood samples are then drawn over 3 hours. - Blood test for DNA (genetic) studies related to obesity, diabetes and related medical problems. - DEXA scan. This test measures body fat. The subject lies on a table while a very small dose of X-rays is passed through the body. - Respiratory chamber. This test measures how many calories the body burns a day and assesses energy balance between intake and expenditure. Subjects stay in a room with two windows, equipped with a sink, toilet, television and DVD player, desk, chair, telephone and bed for 24 hours. The test is repeated five times during the first 18-day admission and 3 times during the second 13-day admission. For the first two sessions, subjects are fed a diet equal to the amount of energy their body uses. For the next 6 stays they are fed double the amount of calories their body usually uses for 5 of the stays and fast (consume nothing but water and soda without caffeine or calories) during 1 stay. The overfeeding diets may be high or low in protein, normal in protein, or high in fat. Blood tests are done on the day of each respiratory chamber session and a 24-hour urine sample is collected for one day while in the chamber. - Eating behavior questionnaires. - Psychological performance tests. Some participants are asked to volunteer to repeat two of the chamber studies to validate the measurements. The repeat session includes only the fasting and the overfeeding with normal protein content. All participants are followed at 6 months with blood tests, a DEXA scan, and urine tests (including pregnancy test for women). At annual visits for years 1 through 7, participants have the 6-month tests plus an oral glucose tolerance test.

The trial is Open with a status of Recruiting.

Investigator: Jonathan Krakoff, M.D.

Referral Contacts: Email: Kateri Ware Phone: (602) 200-5300

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The Food Intake Phenotype: Assessing Eating Behavior and Food Preferences as Risk Factors for Obesity

The prevalence of obesity in the United States has reached alarming proportions with 33% of adults over the age of 20 being overweight. Obesity is more than twice as prevalent, however, in the Pima Indians of Arizona. Although there have been a number of advances in our understanding of the genetics of obesity, the environmental influences on the genetic expression of obesity requires further investigation. In an effort to understand some of the influences on the high prevalence of obesity in the Pima Indians, the present study was designed to investigate eating behaviors and food preferences, most especially the preference for high fat foods, in sib-pairs of Pima Indians who have been previously genotyped in our genomic scan for loci linked to diabetes/obesity. Most specifically, we will utilize several questionnaires and methods of assessing eating behavior and the preference for high fat foods to create a food intake phenotype. In addition, we will study Caucasians so that comparisons can be made between these two groups. We will make these evaluations by assessing eating behavior, food preferences including usual fat intake and preferences for high fat foods, body image perceptions, and energy expenditure. It is hoped that the data gathered from this study will elucidate some of the risk factors for the development of obesity among the Pima Indians.

The trial is Open with a status of Recruiting.

Investigator: Susanne Votruba, Ph.D.

Referral Contacts: Email: Susanne Votruba, Ph.D. Phone: (602) 200-5336

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