EAL

DM: Carbohydrates (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To observe over 6 month period fasting blood glucose, HbA1c, body weight, and BMI in a group of obese patients with type 2 diabetes on a low-carbohydrate diet (LCD) and to compare the results with a control group (CG) on a high-carbohydrate diet.

Inclusion Criteria:

fasting blood glucoe > 6 mmol/l and HbA1c >5.6%
OR use of glucose lowering medication

Exclusion Criteria:

None had manifest heart disease or untreated thyroid illness

Description of Study Protocol:

Recruitment:

All patients were referred from primary care because of failure to achieve control of blood glucose and body weight.
Low carbohydrate diet group patients were self-selected, having contacted the clinic and asking to try a low-carbohydrate diet after attending an informational meeting about low-carbohydrate diets.
Control group patients undertook the ordinary educational program at the clinic.

Design: Nonrandomized Clinical Trial

Blinding used (if applicable): none; control group knew that another group was being formed that would follow a different diet

Intervention (if applicable)

Diet:

LCD group
- 1800 calories for men and 1600 calories for women
- 20% CHO, 30% protein, 50% fat
- CHO limited to vegetables and salad
- all processed CHO excluded
Control Group
- 1600-1800 calories for men; 1400-1600 for women
- 60% CHO, 15% protein, 25% fat

Statistical Analysis none described

Data Collection Summary:

Timing of Measurements

fasting blood glucose and body weight measured at the start of the observation period and after 2, 4, 6, 8, 10, 12, 16, 20, and 24 weeks.
HbA1c measured at the start and at 8, 16, and 24 weeks

Dependent Variables

fasting blood glucose
body weight
HbA1c
insulin needs

Independent Variables

no measures of dietary intake or compliance made

Control Variables: none

Description of Actual Data Sample:

Initial N: 16 in LCD group and 15 in Control Group

Attrition (final N): no attrition mentioned

Age:

LCD group: 57.1±6.2
CG: 58.6±10.1

Ethnicity: not specified

Other relevant demographics: Duration of diabetes for LCD group =13±5.5y; for CG = 8.5±5.4

Anthropometrics: LCD group mean BMI= 100.6 ±14.7; CG 101.5±14.5

Location: Sweden

Summary of Results:

Attendance was good in both groups.

Mean insulin requirements for the LCD group decreased from 60±33 to 39±21 IU/day the first week.

Mean fasting blood glucose decreased in LCD group from 11±2.8 to 6.9±1.2mmol/l. Fasting blood glucose dropped in CG from 12.3±1.8 mmol/l in the same time.

After 24 weeks the LCD group showed lower measures of fasting blood glucose, HbA1c, body weight, and BMI compared to the Control Group.

Other Findings

Six months after the end of the study all but one of the patients from the LCD group had been seen again for follow-up. Mean body weight of those seen was unchanged at 89.5±14.6 kg. Mean HbA1c had increased to 7.0±1.4%, but nine of 15 patients still had an HbA1c in the normal range (below 6.5%), compared to 2 patients at the beginning of the study.

Author Conclusion:

The present observations show that a simple change of the caloric proportion of carbohydrates, protein, and fat in the diet is an effective tool in the management of type 2 diabetes.

Funding Source:

Reviewer Comments:

Data was presented as time series line and bar graphs. No statistical analysis reported. Dietary compliance not measured. Unclear what method was used to measure fasting blood glucose.

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?	No
	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)	No
	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?		No
	4.1.	Were follow-up methods described and the same for all groups?	No
	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%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	No
	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?	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.)	???
	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?		No
	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?	No
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	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?		???
	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?	N/A
	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?	???
	7.5.	Was the measurement of effect at an appropriate level of precision?	N/A
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	N/A
	7.7.	Were the measurements conducted consistently across groups?	N/A
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		No
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	No
	8.2.	Were correct statistical tests used and assumptions of test not violated?	No
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	No
	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)?	No
	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?	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?		No
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
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