Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To examine the association between type of beverages consumed and glucose control in American adults with or without diabetes.
Inclusion Criteria:
  • Defined as having diabetes if answers to NHANES III diabetes questionnaire indicated they had been told they had diabetes and had not been pregnant at the time.
Exclusion Criteria:
Description of Study Protocol:


  • NHANES III multi-stage stratified random sample of the civilian non-institutionalized population of the US, conducted 1988 to 1994. About 32,000 residients with oversampling of youths seniors, and minorities.


  • Grouped number of beverage drinks per month into four categories: None, one to 29, 30 to 59, and 60 or more. There were fewer patients with diabetes who consumed higher amounts of alcoholic beverages and regular soda (N<30), the higher two categories were combined (≤ drinks per month) for these beverages.

Statistical Analysis

  • Linear regression and other methods were used for clustered data to examine the assocaition of hbA1c levels with self-reported intake of carbonated drinks, alcohol, coffee, tea juices and milk, using Sudaan 8.0 software.
Data Collection Summary:

Timing of Measurements

  • Food frequency questionnaire, one-day dietary recall, diabetes questionnaire and measurement of serum HbA1c.
Description of Actual Data Sample:

Initial N

  • 32,000 NHANES III US conducted 1988 to 1994, including 14,900 adults. Of these, 1,024 reported a physician's diagnosis of diabetes.
  • 581 women, 443 men
  • 236 aged 18 to 49 years
  • 495 aged 50 to 64 years
  • 393 aged 65 to 75 years
  • 303 non-Hispanic white subjects
  • 326 African-Americans
  • 364 Mexican-Americans
  • 31 of "other" race.


  • 18 to 75 years.


  • Youths
  • Seniors
  • Minorities.
Summary of Results:

Characteristics of Sample

  • 14,900 adults: Of these, 1,024 reported a physician's diagnosis of diabetes.

    • 581 women, 443 men
    • 236 aged 18 to 49 years
    • 495 aged 50 to 64 years
    • 393 aged 65 to 75 years
    • 303 non-Hispanic white subjects
    • 326 African-Americans
    • 364 Mexican-Americans
    • 31 of "other" race.
  • Persons with diabetes drank significantly less alcohol than those without diabetes (P< 0.001), about half the amount of beer, wine and hard liquor.

  • Adults with diabetes consumed a mean of 30 diet sodas per month, significantly more than the 11 diet sodas per month in those without diabetes.

  • Persons with diabetes drank significantly less regular soda than those without diabetes (three vs. 17 sodas per month)

  • Persons with and without diabetes reported drinking similar amounts of caffeinated coffee and tea, citric juices and other juices.

Mean Number of Drinks Per Month (with SE) by Diabetes Status for Each Beverage, with P Adjusted for Age, Sex and Race

  Diabetes No Diabetes P-Value
Diet Soda 30.4 (2.6) 11.1 (0.4)  <0.0001 
Regular Soda 3.0 (0.60 17.0 (0.6) <0.0001
Total Soda 33.4 (2.7) 28.2 (0.7)  <0.0001
Beer 2.1 (0.4) 5.3 (0.2)  <0.0001 
Wine 0.8 (0.2) 1.6 (0.1)  0.0007 
Hard Liquor 1.1 (0.4) 2.0 (0.1)  0.06 
Total Alcohol 4.8 (0.8) 8.9 (0.3)  <0.0001 
Caffeinated Coffee 36.0 (4.7) 35.0 (1.1)  0.43 
Caffeinated Tea 10.8 (1.2) 12.5 (0.8)  0.39 
Citric Juice 14.0 (1.1) 13.1 (0.3) 0.76
Other Juices 5.7 (0.6) 6.9 (0.2)  0.10 
Milk 25.1 (1.2) 22.5 (0.5)  0.013 

  • Compared with non-drinkers, subjects who had 30 or more drinks per month of alcohol had mean HbA 1c levels of 1.2 units less (P<0.001) in persons with diabetes and 0.2% less (P<0.001) in persons without diabetes.

  • In persons with diabetes, the HbA1c level was associated positively with consumption of diet soda (R=0.14, P=0.025) but not regular soda (R=0.08, P>0.10). In adults with diabetes who drank no diet soda, mean HBA1c  level was greater by 0.4% in those who drank some (one to 29 drinks per month), greater by 0.8% in those who drank 30 to 59 diet sodas per month and greater by 0.7% in those who drank 60 or more per month.

Mean Hemoglobin A 1c Level by Beverage Frequency and Diabetes Status for Each of 11 Beverages Surveyed in NHANES III

    Drinks per Month    
Beverage Status None One to 29 30 to 59 ≥60 P (Trend)
Diet Soda Diabetes 7.3 7.7 8.0 8.2 0.0005
  No Diabetes 5.2 5.2 5.2 5.2 0.33
Caffeinated Coffee Diabetes 7.7 7.8 7.7 8.0 0.39
  No Diabetes 5.2 5.2 5.2 5.3 0.0001
Caffeinated Tea Diabetes 7.8 7.8 7.8 7.8 0.95
  No Diabetes 5.2 5.2 5.3 5.3 0.0007
Citric Juice Diabetes 7.7 8.0 7.6 8.4 0.26
  No Diabetes 5.2 5.2 5.2 5.1 0.004
Other Juices Diabetes 7.7 8.0 8.0 7.1 0.51
  No Diabetes 5.2 5.2 5.2 5.2 0.63
Milk Diabetes 7.3 7.6 8.1 8.0 0.10
  No Diabetes 5.2 5.2 5.2 5.2 0.14
Regular Soda Diabetes 7.8 7.8 7.8 a 0.88
  No Diabetes 5.2 5.2 5.2 5.3 0.011
Wine Diabetes 7.9 7.2 6.5 a 0.016
  No Diabetes 5.2 5.2 5.1 4.7 0.00096
Beer Diabetes 7.9 7.6 6.8 a 0.054
  No Diabetes 5.2 5.2 5.1 5.1 0.09
Hard Liquor Diabetes 7.9 7.2 6.7 a 0.017
  No Diabetes 5.2 5.2 502 5.1 0.022
Total Alcohol Diabetes 8.0 7.5 6.7 a 0.0015
  No Diabetes 5.3 5.2 5.2 5.1 0.0002

a: The 30 to 59 and ≥60 categories are combined because of insufficient numbers of adults with diabetes who consumed 60 or more servings per month.
Author Conclusion:


  • Cross-sectional and cannot make any conclusions about the direction of causality between glucose control and beverage consumption
  • Assessment of beverage consumption was through self-reporting
  • Food frequency questionnaire had no specifications about portion size
  • Limited by survey conducted 10 years ago.

This study shows an inverse cross-sectional association of intake of alcoholic beverages with glucose control in American adults with diabetes and a detrimental association of diet soda consumption with glucose control. These findings indicate the need to investigate further the effect of beverage choice on glucose control by using prospective studies.

Funding Source:
University/Hospital: Dartmouth Medical School
Reviewer Comments:
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? No
2. Was the selection of study subjects/patients free from bias? No
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? No
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? No
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? No
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) Yes
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) No
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? No
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? No
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? No
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? No
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? No
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? No
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? No
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? N/A
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes