Ability to Perform Daily Physical Activities in Individuals with Type 2 Diabetes and Moderate Obesity: A Preliminary Validation of the Impact of Weight on Activities of Daily Living Questionnaire

Abstract

Background:

The aims of this study were (1) to demonstrate the reliability and validity of the Impact of Weight on Activities of Daily Living Questionnaire (IWADL), a measure of ability to perform daily physical activities, in individuals with type 2 diabetes who are moderately obese and (2) to characterize those individuals with low self-reported ability.

Methods:

Data from a web-based survey of individuals with type 2 diabetes and body mass index (BMI) of 30–40 k/mg² were used to calculate Cronbach's α and demonstrate both IWADL factorial and construct validity. These data were entered into a multivariable multinomial logistic regression model with survey variables (demographics, health status, weight- and diabetes-related) as the independent variables and three IWADL scoring groups (Low, Medium, and High) as the dependent variables.

Results:

Study participants were 349 individuals with type 2 diabetes (mean age = 59 years, 44% male, 91% white, mean BMI = 35 k/mg²). Factor analysis indicated a one-factor solution for a seven-item IWADL with Cronbach's α = 0.94. Significant (P < 0.05) relationships were identified between IWADL and variables previously shown to be related to level of physical activity. Ten variables remained independently (P < 0.05) related to IWADL scores, including age, gender, health status, current exercise, using exercise programs or hypnosis as a step to lose weight, and self-reported weight history.

Conclusions:

The IWADL is a reliable and valid measure of the ability of individuals with type 2 diabetes and moderate obesity to perform daily physical activities. This ability may be an important patient-reported end point to include in clinical trials of antihyperglycemic medications that produce weight loss.

Introduction

I n a qualitative study, individuals with type 2 diabetes mellitus (T2DM) and obesity (body mass index [BMI] of 30–35 kg/m²) identified the ability to perform physical daily activities as important and relevant to them. They also expressed the belief that their performance of these daily activities would improve with weight loss of 5–10% of body weight.¹ Physical activity benefits nearly everyone by reducing risk factors for heart disease and stroke and keeping joints flexible, but it is particularly important for people with diabetes as being physically active can improve the body's ability to use insulin and facilitate weight loss.^2

–6 Yet, studies in the United States have estimated that only one-third of individuals with T2DM and obesity are physically active.^7,8

Several antihyperglycemic medications (e.g., incretin mimetics) produce improvements in glycemic control with accompanying weight loss (up to 5–10% of body weight).^9
–11 This weight loss may then facilitate improvement in ability to perform physical activity, which could potentially precipitate more weight loss and all the accompanying benefits. Clinical measures (glycated hemoglobin, weight loss) are the standard end points in evaluating such medications. However, given the importance that individuals with T2DM place on their ability to perform daily physical activities and their belief that this ability would improve with weight loss, a patient-reported measure of ability to perform daily physical activities may also be an informative end point.

Currently, there are generic (e.g., SF-36)¹² and obesity-specific (e.g., Impact of Weight on Quality of Life Questionnaire)¹³ patient-reported outcome (PRO) measures that assess physical function or mobility. However, to our knowledge, there are no existing PRO measures that have been developed in individuals with T2DM who are also obese to assess the ability to perform daily physical activities that are important to them. Accordingly, the first objective of this study was to validate such a measure, the Impact of Weight on Activities of Daily Living Questionnaire (IWADL), via a web-based survey. The survey data offered the opportunity to address a second objective: to identify variables that characterize the group of individuals with T2DM and obesity who report the lowest ability to perform daily physical activities. Insight into the characteristics of this group may assist in understanding the extent to which antihyperglycemic medications that produce weight loss may also improve ability to perform daily physical activity.

Research Design and Methods

Development of the IWADL

Transcripts from six focus groups (n = 54 individuals with T2DM and BMI of 30–40 kg/m²) served as the basis for IWADL item generation. Thirteen items in the areas of flexibility, mobility, and activity level, along with alternative response sets and recall periods, were pretested and refined through two iterative rounds of cognitive interviewing (n = 24 individuals with T2DM and BMI of 25–40 kg/m²). Cognitive interviews indicated that all 13 items should be retained for further testing. Each item asked respondents to indicate their current ability to engage in various daily physical activities, using a 5-point scale (“Unable to do” = 1 to “Not at all difficult” = 5).

Web-based survey

Survey participants were individuals with self-reported T2DM and BMI of 30–40 kg/m² recruited from the ePanel of a large research firm. Survey approval was obtained from the Ethical Review Board of the American Institutes for Research. Data were collected in June 2009.

In addition to the 13 IWADL draft items, the web-based survey included items related to demographics, comorbidities, diabetes complications, current weight, weight 1 year ago, and insulin use. Additional patient-reported measures included items regarding general health, weight history, self-description regarding weight management, perceived glycemic control (three items), and self-description regarding diabetes management. Participants were also administered the Rapid Assessment of Physical Activity (RAPA), a measure designed to assess levels of physical activity among adults older than 50 years of age and is being used in diabetes registries.¹⁴ Scoring of the RAPA results in categorization of respondents into five ordered categories of physical activity (sedentary to active). The RAPA also includes two questions about participation in activities designed to promote muscle strength or flexibility.¹⁴ Additional details about the patient-reported measures are presented in Table 1.

Table 1.

Patient-Reported Measures Administered to Individuals with Type 2 Diabetes and Obesity via a Web-Based Survey (n = 349)

Concept	Number of items	Item(s)	Response set	Scoring
General health	1	In general, how is your health?	a. Excellent b. Very good c. Good d. Fair e. Poor	Categorical: response is used for assignment of category.
RAPA category (Sedentary to Active)	7	Example: I do moderate physical activities every week, but less than 30 min a day or 5 days a week.	Yes or No	Categorical: the “Yes” response to the highest level of activity represented in the 7 items is used for assignment of RAPA category (Sedentary to Active).
Self-reported weight history	1	Which of the following statements best describes you?	a. I have always or almost always been overweight. b. At one time I was not overweight, and I have become overweight gradually over the years. c. At one time I was not overweight, and I became overweight at a distinct point later on (for example, due to quitting sports, pregnancy). d. Over the years, I have gone back and forth between being overweight and not being overweight. e. I do not consider myself overweight. f. None of these	Categorical: response is used for assignment of category.
Self-description regarding weight management	1	Which of the following words best describes how you feel about managing your weight?	a. Committed b. Tentative c. Hopeful d. Hassled e. Overwhelmed f. None of the above	Categorical: response is used for assignment of category.
Perception of glycemic control scale	3	Example: In the past week, how often did you feel that your blood sugars were too high?	a. All of the time b. Most of the time c. Some of the time d. None of the time	Scale scores are minimum = 1, maximum = 4, with higher score corresponding to greater perceived glycemic control.
Self-description regarding diabetes management	1	Which of the following words best describes how you feel about managing your diabetes?	a. Committed b. Tentative c. Hopeful d. Hassled e. Overwhelmed f. None of the above	Categorical: response is used for assignment of category.

RAPA, Rapid Assessment of Physical Activity.

Statistical analysis

Descriptive statistics were calculated for each item. Item reduction followed guidelines for creating evaluation measures,¹⁵ that is, items with large ceiling effects (a large number of respondents endorsing the most positive response) were eliminated from the final IWADL. The criterion for a ceiling effect was set at >33% of respondents endorsing “not difficult at all.” To establish the factorial validity and internal consistency of the final IWADL items, a principal component analysis was performed, and Cronbach's α was calculated. Total IWADL scores were derived by adding item scores (minimum = 1, maximum = 5) and then dividing by the number of items so that the minimum and maximum total scores were 1 and 5, respectively. Higher scores correspond to greater ability to do physical daily activities.

The IWADL scoring distribution was divided into three groups: Low, Medium, and High. The Low group were individuals scoring >1 SD below the mean IWADL score for the total group, the Medium group were individuals scoring between ± 1 SD of the mean, and the High group were individuals scoring >1 SD above the mean. It was hypothesized that construct validity would be demonstrated by the tendency for the lower IWADL scoring groups to be older, female, and white, report less physical activity, be on insulin, and have poorer health status, less education, lower household income, greater BMI and/or less weight loss in the past year, and poorer perceived glycemic control (as a proxy for clinically measured glycemic control). These hypotheses were based on studies exploring associations with or barriers to physical activity in individuals with T2DM and/or obesity.^{7,8,16

–24} Additional analyses conducted using weight-related and diabetes-related variables (e.g., self-descriptions regarding weight and diabetes management) were exploratory. Percentage of body weight loss was calculated by taking the difference between participants' reported current weight and weight 1 year ago and then determining the percentage of body weight lost. Associations between IWADL groups and survey variables were tested using analysis of variance for continuous variables and χ ² test for categorical variables.

To address the second objective, multivariable, multinomial logistic (PROC LOGISTIC, SAS version 9.2, SAS Institute, Cary NC) regression was used to determine variables that were related to the three categories of participants (Low, Medium, and High IWADL). Stepwise variable selection was used, using two-tailed significance tests with α set at 0.05. Odds ratios and their 95% confidence intervals reflect the odds of being in a lower IWADL group.

Results

Study participants

Web-based study participants (n = 349) were mostly white (91%), female (56%), middle-aged (mean [SD] = 58.9 [8.6] years), and obese (BMI mean [SD] = 35 [2.6] kg/m²) (Table 2).

Table 2.

Demographics, Self-Reported Health Status, Comorbidities/Diabetes Complications, and Rapid Assessment of Physical Activity Category, Across Impact of Weight on Activities of Daily Living Questionnaire Groups (n = 349)

	IWADL group
Survey variables	Low (n = 77)	Medium (n = 207)	High (n = 65)	Total (n = 349)	P value
Age [mean (SD)] (years)	60.3 (8.1)	59.4 (8.3)	55.9 (9.6)^{a b}	58.9 (8.6)	<0.01
Gender (% female)	73	54	43	56	<0.01
Race (% white)	88	93	86	91	NS
Education
High school graduate or less (%)	21	23	34	25	NS
Some college (%)	55	46	35	46
College graduate or higher (%)	25	30	31	29
Combined household income
$30,000 or less (%)	38	25	25	28	<0.05
$30,001–$75,000 (%)	52	50	45	49
$75,001 or more (%)	10	26	31	23
General health rating					<0.001
Excellent (%)	0	1	5	1
Very good (%)	4	20	45	21
Good (%)	22	52	45	44
Fair (%)	48	22	6	25
Poor (%)	26	5	0	9
Comorbidities/diabetes complications (% yes)
Arthritis	84	53	31	56	<0.001
Neuropathy (nerve problems causing numbness, tingling, or burning)	62	33	11	35	<0.001
Depression	48	31	12	31	<0.001
Anxiety	39	19	12	22	<0.001
Gastroparesis or other stomach or intestinal disorder	23	14	3	14	<0.01
Angina or coronary heart disease	18	13	5	13	NS
Eye complication of diabetes (e.g., retinopathy)	21	10	8	12	<0.05
Heart attack (myocardial infarction)	17	11	5	11	NS
Foot ulcers or other foot problems	18	10	3	10	<0.05
Cancer	14	8	5	9	NS
Stroke	12	5	2	6	<0.05
Kidney disease	8	7	2	6	NS
Peripheral vascular disease	4	3	0	3	NS
RAPA category (%)
Sedentary (rarely do activity)	21	5	2	8	<0.001
Underactive	22	10	0	11
Underactive regular (light activities)	42	31	11	29
Underactive regular	7	33	32	27
Active	9	22	55	25
Do activities to increase muscle strength (% yes)	8	16	34	17	<0.001
Do activities to improve flexibility (% yes)	16	25	34	24	<0.05

High is significantly (P < 0.05) different from Medium.

High is significantly (P < 0.05) different from Low.

IWADL, Impact of Weight on Activities of Daily Living Questionnaire; NS, not significant; RAPA, Rapid Assessment of Physical Activity.

Item reduction, factorial validity, and internal consistency

Over one-third of participants responded “not difficult at all” to six items. Therefore, because these items demonstrated the specified ceiling effect, they were deleted from further analysis. Factor analysis of the remaining seven IWADL items showed one factor that accounted for 73% of variance with an eigenvalue of 5.1 and all factor loadings ≥0.82 (Table 3). Cronbach's α calculated for the seven-item IWADL was 0.94.

Table 3.

Item Statistics for the Final Seven Impact of Weight on Activities of Daily Living Questionnaire Items (n = 349)

Item	How difficult is it for you to:	% unable to do (floor)	% not at all difficult (ceiling)	Mean	SD	Factor loadings	Item-total correlations
1	… get up from the floor or ground?	4	14	3.3	1.1	0.85	0.79
2	… get down—for example, to sit, squat, or kneel on the floor or ground?	5	24	3.5	1.2	0.85	0.78
3	… stand for 2–3 hours?	14	32	3.4	1.4	0.82	0.76
4	… walk up two flights of stairs?	8	28	3.5	1.3	0.85	0.79
5	… do household chores or yard work that require you to bend over or squat down, such as cleaning the bathtub or weeding?	7	22	3.5	1.2	0.90	0.85
6	… engage in moderate physical activity for 30 min, such as walking quickly, playing softball, playing volleyball, or ice skating?	18	24	3.2	1.4	0.89	0.85
7	… engage in strenuous physical activity for 30 min, such as running, playing basketball, biking, skiing, or swimming laps?	31	8	2.4	1.3	0.84	0.78

Study participants had a mean IWADL score of 3.3 with SD = 1.1. Therefore, the Low group (n = 77, 22%), the Medium group (n = 207, 59%), and the High group (n = 65, 19%) consisted of those participants who had IWADL scores of <2.2, 2.2–4.4, and >4.4, respectively.

Construct validity

Demographics

Significant (P < 0.05) differences in the IWADL groups were found for age, with the mean age of the Low (60.3) and Medium (59.4) groups significantly higher than the High group (55.9). A significant association (P < 0.001) was found between IWADL group and gender, with the Low group consisting of nearly three-quarters females (73%) and the Medium and High groups more closely split equally between males and females (54% and 43%, respectively). A significant (P < 0.05) association was found between IWADL group and combined household income, with 90% of the Low group reporting a combined household income <$75,000 compared with 75% and 70% of the Medium and High groups, respectively. No significant associations were found between IWADL group and either race or education (Table 2).

Health status

A significant (P < 0.001) association was found between IWADL group and general health status, with 74% of the Low group reporting fair to poor health status compared with 27% and 6% of the Medium and High groups, respectively. IWADL group was significantly (P < 0.05) associated with having arthritis, neuropathy, depression, anxiety, gastroparesis or other stomach disorder, diabetes eye complications, foot ulcers, and stroke (Table 2). For most of the diagnoses, the percentage of Low group individuals who reported having a condition was 1.5 times greater than the percentage for the Medium group and more than two times greater than for the High group (e.g., arthritis: Low 84%, Medium 53%, High 31%).

Convergent validity

A significant (P < 0.001) association was found between IWADL group and RAPA category (Table 2). Nearly half (43%) of the Low group was classified as Sedentary or Underactive compared with 15% and 2% of the Medium and High groups, respectively. Similar associations were found between IWADL group and participation in activities designed to increase muscle strength (P < 0.001) or flexibility (P < 0.05).

Weight-related variables

A significant (P < 0.05) association was found between IWADL groups and self-reported weight history. One percent or less of both the Low and Medium groups indicated they were not overweight or could not be described by the item options (always/almost always overweight, became overweight as an adult, have been overweight then not overweight) compared with 6% of the High group. Significant (P < 0.05) differences between the IWADL groups were found in the percentage of weight loss in the last year. The mean percentage of weight loss for the Low group (0.5%) was significantly lower than the mean percentage for the High group (4.4%). Of steps taken to lose/control weight, a significant association was found between IWADL group and both using exercise programs (P < 0.001) and hypnosis (P < 0.05). Only 40% of the Low group reported using exercise programs compared with 54% and 74% of the Medium and High groups, respectively, but 8% of the Low group reported using hypnosis compared with 2% and 0% of the Medium and High groups, respectively. No significant associations were found between IWADL group and participants' BMI or any other steps to control/lose weight or self-description regarding weight management (Table 4).

Table 4.

Weight-Related Variables Across Impact of Weight on Activities of Daily Living Questionnaire Groups (n = 349)

	IWADL group
Weight-related survey variables	Low (n = 77)	Medium (n = 207)	High (n = 65)	Total (n = 349)	P value
Self-reported weight history
Always or almost always overweight (%)	33	30	39	32	<0.05
Became overweight as an adult (%)	53	56	42	53
Have been overweight, then not overweight (%)	13	14	14	14
Do not consider self overweight/none (%)	1	<1	6	2
BMI [mean (SD) kg/m²]	35.4 (2.6)	34.8 (2.7)	34.9 (2.4)	35.0 (2.6)	NS
Percentage of body weight loss from previous year [mean (SD)]	−0.5 (10.4)	−1.7 (7.7)	−4.4 (7.1)^a	−1.9 (8.3)	<0.05
Steps taken to control or lose weight (% yes)
Counting calories	66	61	51	60	NS
Commercial diet	17	16	11	15	NS
Exercise program	40	54	74	55	<0.001
Over the counter medication or food	23	19	19	20	NS
Herbal regimen	18	9	9	11	NS
Commercial program	33	27	20	27	NS
Prescription medication	10	9	3	8	NS
Group support	12	13	9	12	NS
Hypnosis	8	2	0	3	<0.05
Self-description regarding weight management
Committed (%)	20	16	25	18	NS
Tentative (%)	7	8	11	8
Hopeful (%)	20	30	26	27
Hassled (%)	17	15	14	15
Overwhelmed (%)	26	22	14	22
Other (%)	12	9	11	10

High is significantly (P < 0.05) different than Low.

BMI, body mass index; IWADL, Impact of Weight on Activities of Daily Living Questionnaire; NS, not significant.

Diabetes-related variables

A significant (P < 0.001) association was found between IWADL groups and taking insulin: 46% of the Low group reported taking insulin compared with approximately 23% of both the Medium and High groups. Significant (P < 0.001) differences between the IWADL groups were found for perception of glycemic control, with the mean score of the Low (3.1) and Medium (3.2) groups significantly lower (perception of poorer control) than the High group (3.4). No significant association was found between IWADL group and either diabetes duration or self-description regarding diabetes management (Table 5).

Table 5.

Diabetes-Related Survey Variables Across Impact of Weight on Activities of Daily Living Questionnaire Groups (n = 349)

	IWADL group
Diabetes-related survey variables	Low (n = 77)	Medium (n = 207)	High (n = 65)	Total (n = 349)	P value
Diabetes' duration [mean (SD)] (years)	10.5 (7.0)	9.3 (6.6)	8.0 (5.5)	9.3 (6.5)	NS
Taking insulin (% yes)	46	23	22	28	<0.001
Perception of glycemic control [mean (SD) score]^*	3.1 (0.5)	3.2 (0.5)	3.4 (0.5)^a b	3.2 (0.5)	<0.001
Self-description regarding diabetes management
Committed (%)	31	41	42	39	NS
Tentative (%)	4	6	5	5
Hopeful (%)	20	23	22	22
Hassled (%)	12	7	12	9
Overwhelmed (%)	20	9	5	11
Other (%)	14	14	15	14

Perceived glycemic control was scored from 1 to 4, with higher scores corresponding to better control.

High is significantly (P < 0.05) different than Medium.

High is significantly (P < 0.05) different than Low.

IWADL, Impact of Weight on Activities of Daily Living Questionnaire; NS, not significant.

Predictors of membership in the Low IWADL group

When survey variables were entered into the logistic regression model, 10 remained independently and significantly (P < 0.05) predictive of membership in IWADL groups (Table 6). With each 5 year increase in age, the odds of being in a lower IWADL group increased 32%. The odds for males to be in a lower group were only half of that of females. The odds of being in a lower IWADL group among individuals reporting neuropathy or arthritis were two to three times higher than those without neuropathy or arthritis. Those reporting good to very good health status had odds that did not differ significantly from those reporting excellent health, but those reporting poor to fair health had odds nine to 25 times higher to be in a lower IWADL group. Individuals who were categorized by the RAPA as underactive or sedentary were two to 10 times more likely to be in the lower IWADL groups than those who were categorized as active. Those who participated in activities to increase muscle strength were less than half as likely than those who did not to be in lower IWADL groups.

Table 6.

Multivariable, Multinomial Logistic Regression Model with Impact of Weight on Activities of Daily Living Questionnaire Groups as Dependent Variable and Survey Variables as Independent Variable

Independent variable	OR	OR 95% confidence interval	P value
Age: per 5 year increase	1.32	1.13–1.54	< 0.001
Gender: male vs. female	0.52	0.31–0.88	0.01
General health (vs. excellent)			< 0.001
Very good	0.97	0.14–6.92
Good	2.25	0.32–15.69
Fair	9.79	1.30–73.94
Poor	25.07	2.84–221.24
Arthritis	2.21	1.26–3.86	< 0.001
Neuropathy	2.93	1.65–5.17	< 0.001
RAPA score (vs. active)			< 0.001
Sedentary, rarely do activity	6.75	2.15–21.18
Underactive	10.09	3.61–28.10
Underactive regular light activities	5.71	2.60–12.56
Underactive regular	1.79	0.91–3.53
Muscle strength: yes vs. no	0.43	0.22–0.86	0.02
Weight history (vs. not overweight/no description)			0.01
Always or almost always overweight	7.07	0.92–54.72
Became overweight as an adult	13.36	1.74–102.58
Have been overweight, then not overweight	14.13	1.69–118.38
Exercise programs: yes vs. no	0.53	0.31–0.91	0.02
Hypnosis: yes vs. no	7.22	1.42–36.82	0.02

Odds ratios (ORs) reflect odds of decreasing one level in the Low/Medium/High Impact of Weight on Activities of Daily Living Questionnaire groups.

RAPA, Rapid Assessment of Physical Activity.

Individuals who had become overweight as an adult or have been overweight as a child increased the odds of being in a lower IWADL group by seven to 14 times compared with those individuals who did not consider themselves as overweight or described with any of the three weight history options. Those individuals who had used exercise programs as a weight-loss method reduced the odds to be in a lower group by half, but those who used hypnosis increased their odds sevenfold.

Discussion

The first objective of this study was to establish the factorial validity, reliability, and construct validity of the IWADL, a measure designed to assess the ability of individuals with T2DM and BMI of 30–40 kg/m² to perform daily physical activities. Factor analysis showed that, although items were developed in the areas of flexibility, mobility, and level of activity, a one-factor solution was optimal. By eliminating nearly half of the original 13 items because of ceiling effects, the respondent burden was decreased, the potential for showing an improvement in ability to perform physical activities after the introduction of a successful intervention was increased, and internal consistency remained high.

Construct validity of the IWADL was demonstrated by the significant associations found between IWADL scoring groups and variables (e.g., age, gender, income, health status, comorbidities) previously noted or observed in other studies exploring barriers to or associations with physical activity/exercise in individuals with T2DM and/or obesity.^{7,8,16

–24} Convergent validity for the IWADL was demonstrated by the association between IWADL groups and RAPA categories. The IWADL assesses participants' self-reported ability to perform daily physical activities, whereas the RAPA focuses on the actual reported frequency, intensity, and duration of exercise. Yet, as the results showed, the relationship between participants' report of ability and their actual report of exercise is closely linked.

Of the exploratory analyses, several findings were of note. Although mean weight loss over the past year was apparent in all groups, only the High group, on average, had lost an amount near the percentage (5–10%) believed to be clinically beneficial.²⁵ The greater tendency for this group to be categorized as “Active” and to use exercise programs as a step for weight loss may be highlighting the important contribution of increased physical activity to losing weight.

Other associations that were explored but were not significant were those between IWADL groups and self-descriptions regarding weight and diabetes management. Despite the tendency for the Low group to have lost a smaller percentage of body weight in the previous year, use exercise programs for weight control/loss less, and perceive poorer glycemic control than the other groups, this group did not differ in terms of their self-descriptions regarding their weight or diabetes management. As with the other two groups, approximately one-third to one-half described themselves as “hopeful” or “committed” to their weight management, and approximately one-half to two-thirds as “hopeful” or “committed” to their diabetes management.

The second objective of this study, in the context of validating the IWADL, was to characterize the group with the lowest ability to perform daily physical activities. Consistent with the obesity and physical activity literature, when all variables were entered into a logistic model, age, gender, variables pertaining to health status (general, as well as, reported comorbidities/complications), and current exercise participation remained independently predictive of IWADL status. However, the independent contribution of weight history was surprising. In a recent study involving multiethnic sample of individuals with BMI ≥30 kg/m², Powell et al.²⁶ observed that approximately 8% (2% in white individuals) had a body size misperception and, therefore, failed to recognize a need to lose weight. These individuals had a tendency to express feeling healthier than individuals of the same age, underestimate their health risks, and exercise less compared with their counterparts with no body misperception. In this study, it is not possible to establish whether the 2% who did not describe themselves as overweight or a weight history have a body misperception. Therefore, it is not clear whether the tendency for these individuals to be in the higher IWADL groups indicates that this group is in excellent physical condition, despite BMI, or this is a group that underestimates their need for weight loss and perhaps also overestimates their ability to do daily physical activity.

The independent contribution of using exercise programs for weight loss/control to the ability to perform daily activities is intuitive. However, the contribution of hypnosis as a step to lose/control weight deserves further exploration.

Limitations

This was a web-based survey, and recruitment was from a population that has shown interest in participating in surveys; thus findings cannot be generalized to the entire U.S. population of individuals with T2DM and obesity. Effort was made to ensure representation by age, gender, and location, but this was an unweighted sample. All variables were self-reported and therefore could not be confirmed. This research surveyed a relatively narrow segment of individuals (those with T2DM and BMI of 30–40 kg/m²) who mirrored the population in which the IWADL was developed. Although it is assumed that similar reliability and validity would be established for this instrument in a broader population of those with T2DM, further research should be conducted to confirm the accuracy of that assumption. Finally, this was a cross-sectional study; therefore, no causal associations can be specified.

Conclusions

Results indicate that the IWADL is a reliable and valid measure of the ability to perform daily physical activity. Antihyperglycemic medications that promote weight loss may be effective in improving the ability of some individuals with T2DM to perform daily physical activities as a direct effect of that weight loss. The IWADL may prove to be an important PRO end point in clinical trials of such medications.

Nevertheless, for those individuals who have very low ability to perform daily physical activities, specifically because of older age and poorer health status, weight loss alone may produce little improvement in ability to perform daily physical activities. These individuals may be similarly motivated and committed to lose weight and control their diabetes as healthier patients but need special attention and individualized intervention approaches that introduce physical activity appropriate for them to overcome their physical activity limitations.²⁷

Footnotes

Acknowledgments

This study was funded by Eli Lilly and Company.

Author Disclosure Statement

All authors are fulltime employees and shareholders of Eli Lilly and Company.

References

Curtis

, Hayes

, Fehnel

, Zografos

. Assessing the effect of weight and weight loss in obese persons with type 2 diabetes. Diabetes Metab Syndr Obes, 2008; 1:13–23.

National Institute of Diabetes and Digestive and Kidney Diseases. What I Need to Know About Physical Activity and Diabetes, 2008. www.diabetes.niddk.nih.gov. 2011 February .

Colberg

, Sigal

, Fernhall

, Regensteiner

, Blissmer

, Rubin

, Chasan-Taber

, Albright

, Braun

. American College of Sports Medicine; American Diabetes Association: Exercise and type 2 diabetes: the American College of Sports Medicine and the American Diabetes Association: joint position statement. Diabetes Care, 2010; 33:e147–e167.

De Feo

, Di Loreto

, Ranchelli

, Fatone

, Gambelunghe

, Lucidi

, Santeusanio

. Exercise and diabetes. Acta Biomed, 2006; 77,Suppl 1:14–17.

Kirk

, De Feo

. Strategies to enhance compliance to physical activity for patients with insulin resistance. Appl Physiol Nutr Metab, 2007; 32:549–556.

Balducci

, Zanuso

, Nicolucci

, De Feo

, Cavallo

, Cardelli

, Fallucca

, Alessi

, Fallucca

, Pugliese

. Italian Diabetes Exercise Study (IDES) Investigators: Effect of an intensive exercise intervention strategy on modifiable cardiovascular risk factors in subjects with type 2 diabetes mellitus. Arch Intern Med, 2010; 170:1794–1803.

Nelson

, Reiber

, Boyko

. Diet and exercise among adults with type 2 diabetes: findings from the Third National Health and Nutritional Examination Survey (NHANES III) Diabetes Care, 2002; 25:1722–1728.

Moratto

, Hill

, Wyatt

, Ghushchyan

, Sullivan

. Physical activity in U.S. adults with diabetes and at risk for developing diabetes. Diabetes Care, 2007; 30:203–209.

Buse

, Henry

, Han

, Kim

, Fineman

, Baron

. Exenatide-113 Clinical Study Group: Effects of exenatide (Exendin-4) on glycemic control over 30 weeks in sulfonylurea-treated patients with type 2 diabetes. Diabetes Care, 2004; 27:2628–2635.

10.

Harder

, Nielsen

, Tu

, Astrup

. The effect of liraglutide, a long-acting glucagon-like peptide 1 derivative, on glycemic control, body composition, and 24-h energy expenditure in patients with type 2 diabetes. Diabetes Care, 2004; 27:1915–1921.

11.

Kim

, MacConell

, Zhuang

, Kothare

, Trautmann

, Fineman

, Taylor

. Effects of once-weekly dosing of a long-acting release formulation of exenatide on glucose control and body weight in subjects with type 2 diabetes. Diabetes Care, 2007; 30:1487–1493.

12.

Ware

. SF-36 Health Survey Manual and Interpretation Guide. Lincoln, RI: QualityMetric, Inc., 2000.

13.

Kolotkin

, Head

, Hamilton

, Tse C

. Assessing impact of weight on quality of life. Obes Res, 1995; 3:49–56.

14.

Topolski

, LoGerfo

, Patrick

, Williams

, Walwick

, Patrick

. The rapid assessment of physical activity (RAPA) among older adults. Prev Chronic Dis [serial online], 2006. www.cdc.gov/pcd/issues/2006/oct/06_0001. 2009 October 10.

15.

Kirshner

, Guyatt

. A methodological framework for assessing health indices. J Chronic Dis, 1985; 38:27–36.

16.

Boule

, Haddad

, Kenny

, Wells

, Sigal

. Effects of exercise on glycemic control and body mass in type 2 diabetes mellitus. JAMA, 2001; 286:1218–1227.

17.

Thomas

, Alder

, Leese

. Barriers to physical activity in patients with diabetes. Postgrad Med J, 2004; 80:287–291.

18.

Rejeski

, Lang

, Neiberg

, Van Dorsten

, Foster

, Maciejewski

, Rubin

, Williamson

. Look AHEAD Research Group: Correlates of health-related quality of life in overweight and obese adults with type 2 diabetes. Obesity, 2006; 14:870–873.

19.

Bish

, Blanck

, Maynard

, Serdula

, Thompson

, Khan

. Activity/participation limitation and weight loss among overweight and obese US adults: 1999 to 2002 NHANES. MedGenMed, 2007; 9:63.

20.

Cheng

, Gregg

, Rekeneire

, Williams

, Imperatore

, Caspersen

, Kahn

. Muscle-strengthening activity and its association with insulin sensitivity. Diabetes Care, 2007; 30:2264–2270.

21.

Lysy

, Da Costa

, Dasgupta

. The association of physical activity and depression in type 2 diabetes. Diabet Med, 2008; 25:1133–1141.

22.

Balducci

, Zanuso

, Fernando

, Fallucca

, Pugliese

. Italian Diabetes Exercise Study (IDES) Group: Physical activity/exercise training in type 2 diabetes. The role of the Italian diabetes and exercise study. Diabetes Metab Res Rev, 2009; 25,Suppl 1:S29–S33.

23.

Korkiakangas

, Alahuhta

, Laitinen

. Barriers to regular exercise among adults at high risk or diagnosed with type 2 diabetes: a systematic review. Health Promot Int, 2009; 24:416–427.

24.

Zanuso

, Balducci

, Jimenez

. Physical activity, a key factor to quality of life in type 2 diabetic patients. Diabetes Metab Res Rev, 2009; 25,Suppl 1:S24–S28.

25.

de Leiva

. What are the benefits of moderate weight loss? Exp Clin Endocrinol Diabetes, 1998; 106,Suppl 2:10–13.

26.

Powell

, de Lemos

, Banks

, Ayers

, Rohatgi

, Khera

, McGuire

, Berry

, Albert

, Vega

, Grundy

, Das

. Body size misperception: a novel determinant in the obesity epidemic. Arch Intern Med, 2010; 170:1695–1697.

27.

Kirk

, Mutrie

, MacIntyre

, Fisher

. Promoting physical activity in people with type 2 diabetes. Br J Diabetes Vasc Dis, 2002; 2:211–213.