EAL

DM: Carbohydrates (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the effects of sucrose and fructose on serum HbA1c levels in subjects with type 1 and type 2 diabetes.

Inclusion Criteria:

None specifically mentioned.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment not specified

Design : subjects were hospitalized for 24 days, during which time they consumed each of three isocaloric diets for 8 days

Blinding used (if applicable) fructose and sucrose were added to foods, but starch diet likely was easily distinguished from the others

Intervention (if applicable)

55% CHO, 15% protein, 30% fat
carbohydrate variants
- fructose diet: 21% of energy derived from fructose; 14 g fiber
- sucrose diet: 23% of energy derived from sucrose; 11 g fiber
- starch diet: almost all of CHO energy from starch; less than 5% of energy from sucrose and fructose; 19 g fiber
- fructose and sucrose were incorporated into baked goods and into beverages and breakfast cereals
for 3-7 days before the study each subject was hospitalized in order to determine appropriate energy level and to adjust doses of insulin and oral hypglycemic agents

Statistical Analysis

design was balanced with respect to diet sequence by randomly assigning each fo the six possible sequences to two people in each of the two subject groups
each response was analyzed as a univariate and multivariate repeated measure; the analyses were the same, so only the simpler was presented
when significant differences were found, the diet means were compared using Tukey's Honestly significant difference (HSD) based on the studentized range

Data Collection Summary:

Timing of Measurements

blood samples drawn on seventh and eighth days of each diet period
plasma glucose samples were drawn at 30 minutes before and 60, and 120 minutes after each meal and snack, plus an additional sample 240 minutes after the evening snack
plasma fructose, serum triglyceride, serum lactate, serum pyruvate, serum acetoacetate, and serum beta-hydroxybutyrate levels drawn at 30 minutes before and 60 and 120 minutes after breakfast on day eight
samples for plasma fructose and serum triglycreide levels obtained 240 minutes after breakfast on day eight
HbA1c and uric acid obtained on day 8
24-hour urine collections obtained on days seven and and eight for determination of urinary glucose and creatinine excretions and on day 8 for urinary C-peptide excretion.

Dependent Variables

plasma and urine glucose levels
plasma fructose levels
HbA1c
Urine C peptide excretion
serum triglyderide, lactate, pyruvate, acetoacetate, beta-hydroxybutyrate, uric acid, and urine creatinine concentrations

Independent Variables

variations in carbohydrate in diet
subjects encouraged to maintain usual level of physical activity but were discouraged from strenuous physical activity

Control Variables

Description of Actual Data Sample:

Initial N: 12 subjects (6 women) with type 1 diabetes and 12 subjects (7 women) with type 2 diabetes

Attrition (final N): no attrition

Age: type 1 subjects: mean age of 23; type 2 subjects mean age of 62

Ethnicity: not specified

Other relevant demographics: mean duration for subjects with Type 1: 11 years: for subjects with type 2: 7 years; none of the subjects with type 2 were taking insulin

Anthropometrics mean relative weight for subjects with type 1: 103%; for subjects with type 2: 129%

Location: United States

Summary of Results:

Variables	Fructose Diet	Sucrose Diet	Starch Diet	Honestly Significant Difference*
Type 1 subjects
preprandial plasma glucose, mg/dl	123**	198	170	39
1-h postprandial plasma glucose	182	263	231	35
2-h postprandial plasma glucose, mg/dl	191	261	248	38
overall mean plasma glucose, mg/dl	161	235	213	35
urinary glucose excretion, g/24/h	14.3	43.4	30.4	15.8
HbA1c, %	15.1	16.7	16.2	1.4
Type 2 diabetic subjects
preprandial plasma glucose, mg/dl	146	156	151	10
1-h postprandial plasma glucose	184	209	200	14
2-h postprandial plasma glucose, mg/dl	184	205	201	14
overall mean plasma glucose, mg/dl	169	187	181	11
urinary glucose excretion, g/24/h	2.5	4.7	4.5	1.8
HbA1c, %	12.1	12.5	12.8	1.1

*mean values that differ by this value or more are significantly different at the 5% level

** values in italics are significantly different at the 5% level

Other Findings

no significant body weight changes during the three diet periods
no significant differences among diets for triglycerides, serum lactate, serum pyruvate, serum ketone, serum uric acid levels, insulin reactions, or C peptide excretion
Peak postprandial plasma fructose was significantly lower on the starch diet for Type 2 subjects

Author Conclusion:

The use of fructose as a sweetening agent in the diabetic diet can improve glycemic control.

Dietary sucrose does not aggravate hyperglycemia in diabetic individuals to a greater extent than other common carbohydrates.

Funding Source:

Government:

GCRC, NIH

Industry:

Estee Corp

Food Company:

University/Hospital:

University of Minnesota

Not-for-profit

Foundation associated with industry:

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?	Yes
2.	Was the selection of study subjects/patients free from bias?		???
	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?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
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?	N/A
	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?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	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?	N/A
	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?	???
	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?	N/A
	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?	Yes
	6.6.	Were extra or unplanned treatments described?	No
	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?	Yes
	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?	Yes
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