Effects of Caffeinated and Decaffeinated Coffee on Body Weight and Glucose Tolerance

Sponsor

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

Overall Status

Completed

CT.gov ID

NCT00305097

Collaborator

Harvard School of Public Health (HSPH) (Other), Beth Israel Deaconess Medical Center (Other)

Enrollment

Location

Arms

28.1

Actual Duration (Months)

1.6

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

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 or Disease	Intervention/Treatment	Phase
Overweight	Dietary Supplement: Decaffeinated coffee Dietary Supplement: Caffeinated coffee Dietary Supplement: No coffee	N/A

Detailed Description

Study Design

Study Type:

Interventional

Actual Enrollment :

45 participants

Allocation:

Randomized

Intervention Model:

Parallel Assignment

Masking:

Single (Investigator)

Primary Purpose:

Prevention

Official Title:

Effects of Caffeinated and Decaffeinated Coffee on Body Weight and Glucose Tolerance

Actual Study Start Date :

May 1, 2006

Actual Primary Completion Date :

Sep 1, 2008

Actual Study Completion Date :

Sep 1, 2008

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Caffeinated coffee Caffeinated coffee	Dietary Supplement: Caffeinated coffee 5 cups per day for 8 weeks Other Names: Instant Nestle caffeinated coffee
Experimental: Decaffeinated coffee Decaffeinated coffee	Dietary Supplement: Decaffeinated coffee 5 cups per day for 8 weeks Other Names: Instant Nestle decaffeinated coffee
Active Comparator: No coffee	Dietary Supplement: No coffee

Arm

Intervention/Treatment

Experimental: Caffeinated coffee

Caffeinated coffee

Dietary Supplement: Caffeinated coffee

5 cups per day for 8 weeks

Other Names:

Instant Nestle caffeinated coffee

Experimental: Decaffeinated coffee

Decaffeinated coffee

Dietary Supplement: Decaffeinated coffee

5 cups per day for 8 weeks

Other Names:

Instant Nestle decaffeinated coffee

Active Comparator: No coffee

Dietary Supplement: No coffee

Outcome Measures

Primary Outcome Measures

glucose tolerance / insulin sensitivity [4 and 8 weeks]

Secondary Outcome Measures

body weight/fatness, blood pressure, concentrations of blood lipids, adipokines, inflammatory markers [4 and 8 weeks]

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years and Older

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

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, Gastroesophageal reflux disease 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

Locations

	Site	City	State	Country	Postal Code
1	Beth Israel Deaconess Medical Center	Boston	Massachusetts	United States	02215

Sponsors and Collaborators

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Harvard School of Public Health (HSPH)
Beth Israel Deaconess Medical Center

Investigators

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