DM: Protein (2007)
The purpose of this study was to determine the effect of co ingestion of varied amounts of fat and protein in a mixed meal on carbohydrate metabolism in subjects with type 2 diabetes mellitus.
Type 2 diabetes mellitus
Digestion or absorption disorders.
Recruitment: Subjects were hospitalized patients with type 2 diabetes.
Design: Subjects were received 3 different test breakfasts by random assignment on 3 consecutive days after fasting overnight and before taking medications.
Blinding Used (if applicable): not specified
Intervention (if applicable):
Test meals:
Group 1: Isocaloric (400), 60% carbohydrate;
- normal: 10% fat and 15% protein
- fat rich: 15% fat, 0 protein
- Protein rich: 0 fat, 40% protein.
Group 2:
- reduced fat: 310 kcal, 50% carbohydrate, 1% fat, 25% protein
- normal fat: 400 kcal, 50% carbohydrate, 10% fat, 25% protein
- high fat: 500 kcal, 50% carbohydrate, 20% fat, 25% protein.
Statistical Analysis:
- results given as mean ± SEM
- Wilcoxon's test and analysis of variance with Scheffe's procedure used for statistical comparisons
- P<0.05 considered significant
Timing of Measurements: Blood sampling at baseline and after breakfast
- group 1: 30, 60, 120 and 180 minutes
- group 2: 30, 60, 90, 120, 180 and 300 minutes.
Dependent Variables:
- Glucose
- insulin
- c-peptide
- gastric inhibitory polypeptide, measured radioimmunologically by using GIP antibody from rabbits
- triglyceride and glucagon response to meals
Independent Variables
- Group 1: Isocaloric (400), 60% carbohydrate;
- normal: 10% fat and 15% protein
- fat rich: 15% fat, 0 protein
- Protein rich: 0 fat, 40% protein.
Group 2:
- reduced fat: 310 kcal, 50% carbohydrate, 1% fat, 25% protein
- normal fat: 400 kcal, 50% carbohydrate, 10% fat, 25% protein
- high fat: 500 kcal, 50% carbohydrate, 20% fat, 25% protein.
Control Variables: not specified
Initial N: 24 hospitalized patients were divided into 2 matched groups.
Final N: 24
Age:
- Group 1: 65.6±2.6 SEM yr; range 50-78
- Group 2: 66.7±3.1 yr; range 38-74
Ethnicity: not specified
Other relevant demographics:
14 patients treated with glibenclamide and 10 with diet only
Anthropometrics:
- Group 1: BMI: 26.6±1.2
- Group 2: BMI: 25.8±1.2
Location: The study was conducted on hospitalized patients in Heidelberg, Germany
Group 1: mean glucose concentrations were not significantly different among the different test meals.
There were significant differences for insulin after 120 minutes:
high protein | high fat | normal | Significance | |
Insulin pmol/L | 478+164 | 160+ 56 | 246+ 74 | (P<0.05) |
Glucagon was significantly higher at 30 minutes on the protein rich meal.
Triglycerides were significantly higher 180 minutes after the high fat meal.
Group 2: Mean concentrations of glucose, C peptide, insulin, and glucagon showed no significant differences among the test meals.
Triglycerides were significantly higher after the high fat meal at 180 minutes (P<0.05). GIP was significantly higher 120 minutes after the high fat meal.
GIP was not significantly different among the test meals.Neither varying the ratio of fat to protein in group 1 nor increasing the amount of fat in group 2 affected glucose concentrations after the test meals.
Compared with the changes after a standard breakfast, insulin increased after a protein rich meal and decreased after a fat rich meal in group 1, while glucose and GIP remained constant.
In contrast, only GIP showed a significant increase after a high-fat meal in group 2.
In people with type 2 diabetes, glucose and insulin responses to different mixed diets do not appear to be exclusively mediated by GIP.
Protein was confirmed as a potent stimulator of insulin secretion.
University/Hospital: | University of Tubingen |
Quality Criteria Checklist: Primary Research
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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? | 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? | 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%.) | Yes | |
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? | 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? | 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? | ??? | |
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)? | ??? | |
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 | |