EAL

DM: Weight Management (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the effect of modest weight loss (> 9.1kg) on plasma glucose levels in obese subjects with NIDDM and to determine whether clinical parameters such as age or weight could be used to predict the glucose response to diet therapy.

Inclusion Criteria:

1. Fasting plasma glucose >10 mmol/L (180 mg/dL)

2. Obesity (weight >130% ideal body weight)

3. Documented weight loss of >=9.1 kg within 48 months of presentation.

4. No treatment with insulin or oral hypoglycemic agents for 6 months prior to the study.

Exclusion Criteria:

Serious medical illnesses (unstable angina, refractory CHF, renal or hepatic insufficiency)

Description of Study Protocol:

Recruitment:

Records from the Diabetes Unit of Grady Memorial Hospital, Atlanta, GA were reviewed. 135 patients with NIDDM who had lost at least 9.1 kg within 4 years of their first visit to the Diabetes Unit.

Design: Retrospective chart review.

1.Dietary management

a. outpatient fasting for 3-7 days 1-2 times/year followed by a 500 kcal diet for 2 weeks, followed by increase kcal as weight loss was achieved.

b. intensive diet instructions initially and follow-up with RD every 3 months.

2. Laboratory data

a. Fasting or random blood draws for plasma glucose.

Blinding Used (if applicable): not applicable

Intervention (if applicable): not applicable

Statistical Analysis:

Sensitivity, specificity and predictive values were calculated. Results are mean + SEM

Data Collection Summary:

Timing of Measurements

Subjects were separated into 2 groups after weight loss based on plasma glucose:

1. Responders: plasma glucose <=10 mmol/L 41%

2. Nonresponders: plasma glucose >10 mmol/L 59%

Dependent Variables

Plasma glucose

Independent Variables

Control Variables

Description of Actual Data Sample:

Initial N: 135 subjects with NIDDM, 73 females, 62 males

Attrition (Final N): 135 subjects

Age (mean + SD): yr 56.1±1.1

Ethnicity: Not mentioned

Other relevant demographics:

Anthropometrics (mean + SD):

Weight, kg 94±2
% of IBW 165±2
Initial Plasma Glucose, mmol/l: 15.6 + 0.9

Location: Atlanta, GA

Summary of Results:

Weight loss

	0 kg	2.3 kg	4.5 kg	9.1 kg
Plasma glucose (mmol/L)	15.6	12.7*	12.3*	13.7*

For the entire group, mean glucose values at each level of weight loss were significantly lower than baseline (P <0.05)
Those with plasma glucose <10 mmol/L were closer to their ideal body weight (157% vs. 170%, P<0.05).
With weight losses as small as 2.3 kg, there was a significant difference in the plasma glucose level between the responders and non responders (P<0.001) and was even greater after a weight loss of 4.5 kg (P<0.001).
Determined the sensitivity, specificity and predictive value of a plasma glucose level to be <=10 mmol/L after a 2.3 kg and a 4.6 kg weight loss assuming the total weight loss would be 9.1 kg.

Plasma glucose >10 mmol/L after weight loss:

	2.3 kg	4.5 kg
Sensitivity	60%	65%
Specificity	79%	87%
+ predictive value	62%	79%
- predictive value	77%	77%

Author Conclusion:

The plasma glucose after weight losses of 2.3 to 4.5 kg was a good predictor of glucose response to a weight loss of 9.1 kg, with most responders exhibiting improvement in plasma glucose levels early in the course of weight loss.

Based on the results of this study, an approach to the management of obese patients with type 2 diabetes mellitus can be recommended:

1. Initiate a weight loss diet, then follow-up for 3 to 6 months or until the patient has lost between 4.5 to 9.1 kg, whichever occurs first.

2. If plasma glucose decreases satisfactorily, continue the diet treatment.

3. If hyperglycemia remains after a weight loss of 4.5 to 9.1 kg or if the patient has been unable to lose 4.5 kg in 3 to 6 months, dietary measures should be continued, but oral hypoglycemic agents or insulin should be added.

Funding Source:

Government:

NIH

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

One of the limitations of this study was that there was a lack of consistency in the times of drawing blood (fasting vs. random). Even though the percentage of fasting and random blood draws were similar in the responders and nonresponders, it is difficult to place a great deal of predictive value from this study.

This study does demonstrate that weight loss improves glycemic control in some, but not all individuals with type 2 diabetes mellitus.

Since many with type 2 diabetes have the disease a number of years before a diagnosis is made, waiting for weight loss to occur before adding medications to lower blood glucose is questionable.

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?	Yes
	2.2.	Were criteria applied equally to all study groups?	???
	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?		No
	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.)	No
	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")?	No
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?	Yes
5.	Was blinding used to prevent introduction of bias?		???
	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?	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?	???
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?	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?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	Yes
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)?	N/A
	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