Effects of Caffeinated and Decaffeinated Coffee on Body Weight and Glucose Tolerance - Full Text View

Sponsored by:	National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Information provided by:	National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
ClinicalTrials.gov Identifier:	NCT00305097

Purpose

Habitual consumption of coffee may have substantial beneficial effects on glucose metabolism according to recent findings of epidemiological studies in the U.S., Europe, and Japan. However, data from longer-term human intervention studies with appropriate outcome measures are lacking. We will study the effects of caffeinated and decaffeinated coffee consumption on body fatness, insulin sensitivity and glucose tolerance that may underlie the observed associations with a lower risk of type 2 diabetes in a randomized controlled trial. We hypothesize that both caffeinated and decaffeinated coffee will improve insulin sensitivity and glucose tolerance. Before starting a larger, long-term intervention study, we will conduct a pilot study to test the feasibility of such a trial.

The pilot study will be an 8-week parallel trial in 45 overweight individuals, who will be randomized to drinking 5 cups per day of 1) caffeinated coffee (n=15), 2) decaffeinated coffee (n=15), or 3) water (n=15). Body fatness (weight, waist circumference, bioelectrical impedance), insulin sensitivity (HOMA model), and glucose tolerance (oral glucose tolerance test) will be the primary outcomes. We will assess the adherence of participants to their assigned treatment by measuring serum caffeine concentrations, documentation of coffee use in diaries by the participants, and counting unused coffee packets. We will also obtain feedback from participants on how to improve compliance in a future trial. If successful, this study will form the basis for a definitive trial of coffee consumption, body fatness, and glucose tolerance. Given the extensive use of coffee and the rapidly increasing health burden of type 2 diabetes, such a trial would have important public health implications.

Condition	Intervention
Overweight	Behavioral: Decaffeinated coffee Behavioral: caffeinated coffee

Study Type:	Interventional
Study Design:	Prevention, Randomized, Single Blind (Investigator), Placebo Control, Parallel Assignment, Safety/Efficacy Study
Official Title:	Effects of Caffeinated and Decaffeinated Coffee on Body Weight and Glucose Tolerance

Resource links provided by NLM:

MedlinePlus related topics: Caffeine Diabetes

Drug Information available for: Dextrose

U.S. FDA Resources

Further study details as provided by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK):

Primary Outcome Measures:

glucose tolerance / insulin sensitivity [ Time Frame: 4 and 8 weeks ] [ Designated as safety issue: No ]

Secondary Outcome Measures:

body weight/fatness, blood pressure, concentrations of blood lipids, adipokines, inflammatory markers [ Time Frame: 4 and 8 weeks ] [ Designated as safety issue: No ]

Estimated Enrollment:	45
Study Start Date:	March 2006
Estimated Study Completion Date:	September 2008
Estimated Primary Completion Date:	September 2008 (Final data collection date for primary outcome measure)

Arms	Assigned Interventions
1: Experimental Caffeinated coffee	Behavioral: caffeinated coffee 5 cups per day for 8 weeks
2: Experimental Decaffeinated coffee	Behavioral: Decaffeinated coffee 5 cups per day for 8 weeks

Detailed Description:

Habitual consumption of coffee may have substantial beneficial effects on glucose metabolism according to recent findings of epidemiological studies in the U.S., Europe, and Japan. However, data from longer-term human intervention studies with appropriate outcome measures are lacking. We will study the effects of caffeinated and decaffeinated coffee consumption on body fatness, insulin sensitivity and glucose tolerance that may underlie the observed associations with a lower risk of type 2 diabetes in a randomized controlled trial. We hypothesize that both caffeinated and decaffeinated coffee will improve insulin sensitivity and glucose tolerance. Before starting a larger, long-term intervention study, we will conduct a pilot study to test the feasibility of such a trial.

The pilot study will be an 8-week parallel trial in 45 overweight individuals, who will be randomized to drinking 5 cups per day of 1) caffeinated coffee (n=15), 2) decaffeinated coffee (n=15), or 3) water (n=15). Body fatness (weight, waist circumference, bioelectrical impedance), insulin sensitivity (HOMA model), and glucose tolerance (oral glucose tolerance test) will be the primary outcomes. We will assess the adherence of participants to their assigned treatment by measuring serum caffeine concentrations, documentation of coffee use in diaries by the participants, and counting unused coffee packets. We will also obtain feedback from participants on how to improve compliance in a future trial. If successful, this study will form the basis for a definitive trial of coffee consumption, body fatness, and glucose tolerance. Given the extensive use of coffee and the rapidly increasing health burden of type 2 diabetes, such a trial would have important public health implications.

Eligibility

Ages Eligible for Study:	18 Years and older
Genders Eligible for Study:	Both
Accepts Healthy Volunteers:	Yes

Criteria

Inclusion Criteria:

Aged at least 18 years with an ability and willingness to give written informed consent.
Body mass index 25-35 kg/m2
Users of at least 2 cups of caffeinated coffee per day who are willing to be randomized to any of the interventions.
Non-smoking

Exclusion Criteria:

Any condition/illness that may affect the study outcomes or would make participation potentially harmful such as pregnancy or breastfeeding, diabetes mellitus, heart disease, stroke, hypertension, malabsorption syndromes, GERD, a history of ulcer, according to a detailed medical history.
Abnormal hepatic function (liver function test > twice the normal range), abnormal renal function (creatinine > 1.1 mg/dl), fasting plasma glucose in the diabetic range (>/= 126 mg/dl), or blood pressure > 140/90 mmHg.
Present alcoholism or drug abuse or use of medications that could interfere with the treatment including bronchodilators, quinolone antibiotics, monoamine oxidase inhibitors, anxiolytics, ranitidine, corticosteroids, growth hormone, antihypertensives.

Contacts and Locations

Please refer to this study by its ClinicalTrials.gov identifier: NCT00305097

Locations

United States, Massachusetts
Beth Israel Deaconess Medical Center
Boston, Massachusetts, United States, 02215

Sponsors and Collaborators

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Investigators

Principal Investigator:	Rob M van Dam, PhD	Harvard School of Public Health
Principal Investigator:	Christos Mantzoros, MD	Beth Israel Deaconess Medical Center

More Information

No publications provided

Responsible Party:	Harvard School of Public Health ( Rob M. van Dam )
Study ID Numbers:	DK46200, P30 DK46200
Study First Received:	March 20, 2006
Last Updated:	July 24, 2008
ClinicalTrials.gov Identifier:	NCT00305097 History of Changes
Health Authority:	United States: Federal Government

Keywords provided by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK):

coffee
caffeine
glucose tolerance

body weight
insulin sensitivity
randomized controlled trial

Study placed in the following topic categories:

Caffeine citrate
Body Weight
Signs and Symptoms

Caffeine
Overweight
Insulin

Additional relevant MeSH terms:

Body Weight
Signs and Symptoms
Overweight

ClinicalTrials.gov processed this record on August 24, 2009