EAL

DM: Carbohydrates (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

1. To examine the relationship of calculated dietary glycemic index (GI) of European outpatients with type 1 diabetes to HbA1c and serum lipids.

2. To determine whether potential associations differed between persons from southern European centers and northern, western, and eastern European centers.

Inclusion Criteria:

diagnosed with diabetes before the age of 36
continuous need for insulin 1 year after diagnosis
completed a 3-day diet record

Exclusion Criteria:

96 participants from one center for the EURODIAB study were excluded because only 18% of them had plausible energy intakes based on their 3-day food records.
incomplete demographic data
taking lipid-lowering medications, oral hypoglycemic agents, or both

Description of Study Protocol:

Recruitment:

subjects were from the EURODIAB IDDM Complications Study
in each center a random sample of participants ages 15-60 was selectd from defined strata in terms of age, sex, and duration of diabetes.

Design: Cohort study

Blinding used (if applicable): not applicable

Intervention (if applicable): not applicable

Statistical Analysis

distributions for HbA1c, LDL cholesterol, and triglycerides were log-transformed for analysis
least-squres regression used to analyze the glycemic index (GI) for relations with HbA1c or serum lipids
distribution of the GI was grouped into quartiles and least-square means of HbA1c and serum lipids calculated for each quartile
trend testing performed across quartiles of GI: t test performed to test whether the parameter estimate for the variable was significantly different from zero.

Data Collection Summary:

Timing of Measurement: measurements performed as part of assessment for EURODIAB study

Dependent Variables

HbA1c, measured in a central laboratory using enzyme immunoassay
total cholesterol, HDL, triglyderides using standard enzymatic methods

Independent Variables

nutritional intake determined by a food record kept for 2 workdays and a Sunday
completed record was checked by the dietitian at each center for completeness and quantification of food items
records were coded by the dietitian at each center and analyzed at the Nutrition Coordinating Center in Dusseldorf, Germany.
Nutrient intake:
- total fat
- saturated fat
- monounsaturated fat
- polyunsaturated fat
- choleterol
- protein
- carbohydrate
- fiber
- alcohol
- energy
- glycemic index, using white bread as the standard

Control Variables

total energy
fiber
self-reported alcohol consumption
sex
age
weight status
smoking status

Description of Actual Data Sample:

Initial N: 2810 met inclusion criteria; 50.8% male

Attrition (Final N): 2810

Age: 32.9±10.2

Ethnicity: not specified

Other relevant demographics:

duration of diabetes: 14.6±9.3

Anthropometrics:

Location: Europe

Summary of Results:

HbA1c concentrations in quartiles of glycemic index in 2054 European patients with type 1 diabetes

Median Glycemic Index	HbA1c, %
	Bivariate analysis²
74.9	6.04 (5.90, 6.19)
79.8	6.24 (6.08, 6.40)
83.6	6.60 (6.43, 6.77)
88.5	6.60 (6.44, 6.77)

²P for trend = 0.0001

3 Adjusted for energy and fiber content, alcohol consumption, sex, age, weight status, and smoking status

Other Findings

An independent association of GI with HDL was noted in patients from northern, western, and eastern European centers.

Author Conclusion:

European patients with type 1 diabetes improved their glycemic control as a result of preferred consumption of low-GI foods, irrespective of fiber intake.

Funding Source:

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?		Yes
	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?	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?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	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?	Yes
	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?	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.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	Yes
	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?		N/A
	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?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	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?		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?	N/A
	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?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
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