EAL

Diabetes and Carbohydrates

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the circulating glucose response over 24 hours to mixed meals that contained a typical amount of carbohydrate, but very little starch and a large amount of fruits and nonstarch vegetables. The results were compared with more typical American meals consumed by the same individuals.

Inclusion Criteria:

Met the National Diabetes Group criteria for the diagnosis of type 2 diabetes

Exclusion Criteria:

Treatment with oral hypoglycemic agents or insulin

Description of Study Protocol:

Recruitment: not mentioned

Design

1. Subjects were admitted to the study unit and received one of 3 experimental diets in random order.

2. Study diets:

a. high carbohydrate, high starch: 55% carbohydrate, 30% fat, 15% protein
b. usual American diet: 40% carbohydrate, 40% fat, 20% protein c. usual carbohydrate, low starch: 43% carbohydrate, 34% fat, 22% protein

3. Study period;

a. study diets were consumed on days 1, 4, and 7 of the study.
b. identical meals were consumed for breakfast, lunch and dinner at 0800, 1200 and 1700 and snack at 2100
c. calorie distribution was 29.5% at each meal and 11.5% at snack.

4. Blood sampling

a. 10- 12 h fast prior to sampling
b. indwelling catheter was used for taking blood samples at 0730, 0745, 0800, 30 minutes after each meal and hourly throughout the 24 h period.

Blinding Used (if applicable): Not used

Intervention:

	High-carbohydrate, high-starch diet	Typical American diet	Experimental Diet (low-starch)
Carbohydrate, %	55	40	43
Protein, %	15	20	22
Fat, %	30	40	34
Kcal/day	2052	2098	2052

Statistical Analysis

net 24-h area responses were calculated using a computer program based on the trapezoid rule
statistics determined using either Student's t test for paired variables, analysis of variance, or the correlation coefficient, as appropriate

Data Collection Summary:

Timing of Measurements- see study design, above

Dependent Variables

24-h plasma glucose area response
plasma glucose concentration, by glucose oxidase method
24-h integrated serum insulin area response
Serum triglyceride response

Independent Variables:

All subjects had consumed a diets containing at least 200 mg of carbohydrate and adequate calories for 3 days before testing.
monosaccharide content of diet

	Glucose (g)	fructose (g)	galactose (g)
High starch	247	32	12
American	189	19	22
Low Starch	134	75	7

Control Variables: none

Description of Actual Data Sample:

Initial N: 6 males

Attrition (final N): 6 males

Age: 62±2.2 yrs

Ethnicity: not specified

Other Relevant Demographics:

HgA1c: 9.5 ± 0.8%

mean fasting glucose of 155±13.9

time since diagnosis of diabetes in the range of 6 weeks to 4 years

Anthropometrics: BMI 31.3±1.3

Location: Minnesota

Summary of Results:

Other Findings:

The integrated 24-h plasma glucose area response was statistically significantly smaller after ingestion of the low-starch meals compared with the high-starch, high carbohydrate meal or the typical American meal (P<0.05)

The glucose area response after the low-starch meal was only 3% of that after the high-carbohydrate meal and 4% of that after the typical American meal.

The 24-h integrated serum insulin area response was significantly less after the low-starch meal compared with the high-starch meal or the typical American meal (P<0.05).

The insulin area response after the low-starch meal was 60% of the response of the high-carbohydrate meal and 54% of the American meal.

The mean 24-h integrated TG area response was similar for the high starch and typical American diet and was higher after the low starch meal, but not statistically higher.

Author Conclusion:

A diet in which fruits, nonstarch vegetables, and dairy products are emphasized may be useful for people with type 2 diabetes mellitus.

It is possible to design a diet that is not high in fat and the ingestion of which results in a very small increase in the 24-h integrated plasma glucose response in subjects with untreated type 2 diabetes mellitus.

Funding Source:

Government:

NIH, Dept. of Veterans Affairs

Industry:

national dairy promotion and research board, National Dairy Council

Commodity Group:

Reviewer Comments:

A limitation of this study is the fiber content of the study diet was not reported. The usual carbohydrate, low-starch diet included 100 g each of fresh orange, apple, and prunes, which would increase the fiber content of the diet. These fruits also have a low glycemic index. Fructose increased TG response greater than glucose or galactose.

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)	No

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?	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?	???
3.	Were study groups comparable?		N/A
	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?	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?		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?		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?	???
	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?	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?	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?	No
	8.2.	Were correct statistical tests used and assumptions of test not violated?	???
	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?	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