EAL

GDM: Carbohydrate (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the effects of ingestion of fructose, protein, or a combination of fructose and protein on circulating glucose, insulin, and c-peptide responses.

Inclusion Criteria:

Inclusion criteria:

1. meet criteria for diagnosis of type 2 diabetes of the National Diabetes Data Group.

2. Normal thyroid, renal and liver function tests

3. No medications for diabetes

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment: subjects recruited from the Clinical Research Center, University of Minnesota.

Design: subjects fasted overnight and then were given either 25 g fructose, 25 g protein, or 25 g protein plus 25 g fructose, or water only at 0800.

Blinding Used (if applicable): not specified

Intervention (if applicable):

All subjects fasted for 10 h and an indwelling catheter was used to obtain blood samples.
Subjects consumed all test meals by random assignment.
Test meals:
- 25 g fructose dissolved in 250 ml water
- 25 g protein (147 g, 0.5% fat cottage cheese)
- 25 g fructose + 25 g protein

Statistical Analysis:

areas under the curves were calculated using the trapezoidal rule
areas were calculated using either the initial fasting value or the concentration of the respective hormone or metabolite, measured over the 5-h period after the ingestion of water only.
statistics were determined using Student's t test for paired variates.

Data Collection Summary:

Timing of Measurements:

Blood obtained before the test meal and at 0.5, 1, 2, 3, 4 and 5 h after the beginning of the meal.

Dependent variables

Plasma glucose, glucagon, urea nitrogen
Serum insulin and triglycerides
Area responses for glucose, glucagon, urea nitrogen, insulin and triglycerides

Independent Variables:

Test meals:
- 25 g fructose dissolved in 250 ml water
- 25 g protein (147 g, 0.5% fat cottage cheese)
- 25 g fructose + 25 g protein

Control Variables:

age
concurrent diagnoses
duration of diabetes
HbA1c

Description of Actual Data Sample:

Initial N: 7 men

Final N: 7

Age: 42-75 years

Ethnicity: not specified

Other relevant demographics:

all subjects had chronic medical conditions in addition to diabetes
duration of diabetes: new to 12 years
HbA1c: 6.5-9.4 %

Anthropometrics: BMI range 24-36

Location: United States

Summary of Results:

The glucose concentration was only modestly increased and the area responses were similar when protein, fructose, or the combination was ingested. Thus, the glucose response to the combination was less than additive.

The insulin area response to protein was 2.5-fold greater than to fructose, and the response to the two nutrients was additive and quantitatively similar to the response to 50 g glucose.

The glucagon area response was less than additive, i.e., there was an interaction between the protein and fructose that resulted in smaller than expected response.

Author Conclusion:

When protein and fructose were ingested together, the insulin response was similar to that following ingestion of 50 g glucose. It also was as expected based on the response to the individual nutrients. In contrast, the glucose and glucagon responses were significantly less than expected. These data may be useful in dietary planning for subjects with type 2 diabetes mellitus.

Funding Source:

Government:

NIH, Dept. of Veterans Affairs

Reviewer Comments:

The results could have been presented in a way that was more understandable in the text.

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?	Yes
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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
3.	Were study groups comparable?		No
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	No
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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?	N/A
	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.)	N/A
	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?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	No
	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.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	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?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	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?	Yes
	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?	Yes
	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?		Yes
	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?	Yes
	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)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	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?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes