Preventive-Care Knowledge and Practices Among Persons with Diabetes Mellitus -- North Carolina, Behavioral Risk Factor Surveillance System, 1994-1995

Diabetes mellitus is the leading cause of lower-extremity amputation, end-stage renal disease, and blindness among persons aged 18-65 years in the United States. Diabetes preventive care resulting in improved self-care, better glycemic control, and regular foot and eye examinations can substantially reduce the complications of diabetes (1-4). Assessment of the level of preventive care among persons with diabetes can assist in targeting public health efforts to reduce complications. To estimate the prevalence of diabetes and the levels of preventive-care knowledge and practices among persons with diabetes in North Carolina, the North Carolina Office of Epidemiology and the state Diabetes Control Program (DCP), in collaboration with CDC, analyzed data from the Behavioral Risk Factor Surveillance System (BRFSS) for 1994-1995. This report summarizes the results of that analysis, which indicate a low level of diabetes preventive-care knowledge and practices among persons with diabetes in North Carolina.

The BRFSS is a state-based, random-digit-dialed telephone survey of the U.S. civilian, noninstitutionalized population aged greater than or equal to 18 years. The DCP used aggregated data from the 1994 and 1995 BRFSS in North Carolina (n=5477). Respondents were considered to have diabetes if they answered "yes" to the core question, "Has a doctor ever told you that you have diabetes?" (women who were told they had diabetes only during pregnancy were not classified as having diabetes). Preventive-care knowledge and practices included whether respondents ever had performed any self-monitoring of blood glucose (SMBG); were aware of glycosylated hemoglobin or hemoglobin "A one C" (HbA1c); or during the preceding year had visited a health-care professional (HCP) for their diabetes, had had a dilated-eye examination, or had had an HCP examine their feet at least once. Data were analyzed using SUDAAN, which allows for the complex survey design of BRFSS. All estimates were weighted to reflect the adult population of North Carolina. Chi-square tests were used to determine statistically significant differences in preventive-care knowledge and practices stratified by insulin use and other characteristics of persons with diabetes. Logistic regression was used to test for trends by age.

Overall, 4.4% (95% confidence interval {CI}=3.9%-5.0%) of adults in North Carolina (230,200 persons) reported that a doctor had told them they had diabetes. Among persons with diabetes, 38% were treated with insulin, 41% were aged greater than or equal to 65 years, 56% were women, 65% were non-Hispanic white, 57% had at least a high school education, and 89% had some form of health insurance (Table_1).

Levels of knowledge and preventive-care practices differed significantly for insulin use and age (Table_2). Overall, 83% of persons with diabetes reported that they performed SMBG, and SMBG was more common among persons treated with insulin than among persons not treated with insulin (94% versus 76%, p less than 0.05). Approximately one fourth (26%) of persons with diabetes were aware of HbA1c; however, knowledge of HbA1c decreased with increasing age (p less than 0.05) (range: 42% among those aged 18-44 years to 18% among those aged greater than or equal to 65 years).

Overall, 93% of adults with diabetes had visited a HCP for diabetes care at least once during the preceding year, and persons treated with insulin were more likely than persons not treated with insulin to have made a visit for diabetes care (99% versus 89%, p less than 0.05). Although the likelihood of having made a diabetes care visit increased with increasing age (p less than 0.05), the likelihood was high (greater than 85%) for all age groups and across all other characteristics. A total of 65% of adults with diabetes had had a dilated-eye examination during the preceding year; the prevalence of examinations was higher among persons treated with insulin than among those not treated with insulin (73% versus 60%, p less than 0.05) and increased with increasing age (p less than 0.05) (range: 54% among those aged 18-44 years to 74% among those aged greater than or equal to 65 years). Among persons with diabetes who had visited an HCP during the preceding year for diabetes care, 62% had had at least one foot examination during the preceding year, and foot examinations were more common among persons treated with insulin than among persons not treated with insulin (74% versus 53%, p less than 0.05); the prevalence of examinations increased with increasing age (p less than 0.05) (range: 46% among those aged 18-44 years to 69% among those aged greater than or equal to 65 years).

Reported by: RA Bell, PhD, K Passaro, PhD, E Lengerich, VMD, Office of Epidemiology; M Norman, MPH, Diabetes Control Program, Div of Health Promotion, North Carolina Dept of Health and Human Svcs. Epidemiology and Statistics Br, Div of Diabetes Translation, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note

Editorial Note: Diabetes-related preventive-care practices are important for reducing the development and progression of diabetes complications and disability and some are cost-effective (5,6). Efforts that result in improved glycemic control can reduce the onset of diabetic eye disease, kidney disease, and neuropathy (1-4). Early detection and treatment of eye disease can prevent blindness, and foot care can prevent conditions that require amputations (3,4).

Despite the importance of diabetes-related preventive-care knowledge and practices, the BRFSS findings documented low levels of some knowledge and practices in North Carolina. The lower proportion of any SMBG among those who were not treated with insulin may have reflected limited understanding of the severity of diabetes and the importance of monitoring glucose levels or barriers within the health system (e.g., noncoverage of monitoring supplies for persons with diabetes who are not treated with insulin). The low level of knowledge of HbA1c suggests that comprehensive diabetes education has not been provided effectively to persons with diabetes. Although most persons with diabetes had visited a health-care provider during the preceding year, only 65% and 62% had received a dilated-eye examination or foot examination, respectively, underscoring the need for incorporation of comprehensive preventive-care practices into routine health care for all persons with diabetes.

The findings in this report are subject to at least two potential limitations. First, data about diabetes status were self-reported; however, self-reported data about diabetes status have been established to be both valid and reliable (7-9). Second, despite some differences in prevalences of knowledge and preventive-care practices by sex, race/ethnicity, education, and health insurance status, these differences were not statistically significant. However, the failure to achieve statistically significant differences may reflect small sample sizes instead of the lack of true differences.

The North Carolina Diabetes Advisory Council is developing diabetes-care guidelines for primary-care practitioners in that state. In particular, the council has updated the North Carolina Diabetes Self-Management Education Curriculum to include findings from the Diabetes Control and Complications Trial (1,6) and has fostered partnerships between schools, health departments, and communities to provide diabetes self-management education for residents of North Carolina and their families at no cost. In addition, to facilitate diabetes self-management, in 1997 the legislature enacted a law requiring state-licensed health insurance payers and health-maintenance organizations to cover the cost of medically appropriate and necessary services, including diabetes outpatient self-management training, educational services, equipment, supplies, medications, and laboratory procedures used in the treatment of diabetes.

CDC encourages state diabetes-control programs to use BRFSS data and to include the diabetes module for the surveillance of diabetes and related preventive-care practices. From 1994 to 1997, the number of states that included the diabetes module in their BRFSS questionnaire increased from 22 to 43. In North Carolina, BRFSS data are essential for the surveillance of diabetes, and the North Carolina DCP has used these data to increase awareness of the prevalence of diabetes, identify groups for which knowledge and preventive-care practices need to be improved, and evaluate progress toward achievement of disease-prevention and -control objectives. BRFSS data also can be used to provide comparison data for managed-care organizations serving patients with diabetes (10) and to monitor the quality of care for patients with diabetes who are Medicare recipients.

References

1. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;329:977-86.

2. Ohkubo Y, Kishikawa H, Araki E, et al. Intensive insulin therapy prevents the progression of diabetic microvascular complications in Japanese patients with non-insulin-dependent diabetes mellitus: a randomized prospective 6-year study. Diabetes Res Clin Pract 1995;28:103-17.

3. Litzelman DK, Slemenda CW, Langefeld CD, et al. Reduction of lower extremity clinical abnormalities in patients with non-insulin-dependent diabetes mellitus: a randomized, controlled trial. Ann Intern Med 1993;119:36-41.

4. Ferris FL III. How effective are treatments for diabetic retinopathy? JAMA 1993;269:1290-1.

5. Eastman RC, Javitt JC, Herman WH, Dasbach EJ, Harris MI. Prevention strategies for non-insulin dependent diabetes mellitus: an economic perspective. In: LeRoith D, Taylor SL, Olefsky JM, eds. Diabetes mellitus. Philadelphia: Lippincott-Raven, 1996:621-30.

6. The Diabetes Control and Complications Trial Research Group. Lifetime benefits and costs of intensive therapy as practiced in the Diabetes Control and Complications Trial. JAMA 1996; 276:1409-15.

7. Kehoe R, Wu SY, Leske MC, Chylack LT Jr. Comparing self-reported and physician-reported medical history. Am J Epidemiol 1994;139:813-8.

8. Stein AD, Lederman RI, Shea S. The Behavioral Risk Factor Surveillance System questionnaire: its reliability in a statewide sample. Am J Public Health 1993;83:1768-72.

9. Edwards WS, Winn DM, Kurlantzick V, et al. Evaluation of National Health Survey Diagnostic Reporting. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, National Center for Health Statistics, 1994. (Vital and health statistics; vol 2, no. 120).

10. CDC. Diabetes-specific prevention-care practices among adults in a managed-care population -- Colorado, Behavioral Risk Factor Surveillance Summary, 1995. MMWR 1997;46:1018-23.

TABLE 1. Distribution of selected characteristics among adults with diabetes --
North Carolina, Behavioral Risk Factor Surveillance System, 1994-1995 *
===========================================================================================
Characteristic                 Sample size+   Weighted no. &      (% @)     (95% CI **)
-------------------------------------------------------------------------------------------
Insulin use
 Insulin                            106           87,800       ( 38.4)   (32.2%-44.6%)
 No insulin                         171          140,900       ( 61.6)   (55.4%-67.8%)
Age group (yrs)
 18-44                               42           39,400       ( 17.2)   (12.0%-22.3%)
 45-64                              102           97,000       ( 42.2)   (35.5%-48.9%)
  >=65                              133           93,400       ( 40.6)   (34.2%-47.1%)
Sex
 Women                              168          128,100       ( 55.6)   (49.0%-62.3%)
 Men                                110          102,100       ( 44.4)   (37.3%-51.0%)
Race/Ethnicity++
 White non-Hispanic                 180          149,800       ( 65.1)   (58.5%-71.3%)
 Black non-Hispanic                  80           65,300       ( 28.4)   (22.5%-34.3%)
 Other                               18           15,100       (  6.6)   ( 3.3%- 9.8%)
Education level
 Less than high school              127           97,700       ( 42.8)   (36.1%-49.4%)
diploma
 High school graduate or more       149          130,700       ( 57.2)   (50.6%-63.9%)
Health insurance coverage
 Yes                                250          204,400       ( 88.8)   (84.3%-93.3%)
 No                                  28           25,800       ( 11.2)   ( 6.8%-15.7%)
Total                               278          230,200       (100.0)
-------------------------------------------------------------------------------------------
*  Date for 1994 and 1995 were aggregated.
+  For some characteristics, the sample size may not equal 278 because of missing data
   or categories not shown.
&  Two-year average.
@  For some characteristics, the percentages may not add to 100 because of rounding.
** Confidence interval.
++ Numbers for racial/ethnic groups other than black and white were too small for
   meaningful analysis.
===========================================================================================

TABLE 2. Prevalence* of diabetes knowledge and preventive-care practices among adults with diabetes, by selected characteristics --
North Carolina, Behavioral Risk Factor Surveillance System, 1994-1995 +
========================================================================================================================================
            Examination
                                                                                                     -----------------------------------
Characteristic                 Monitored blood glucose&    Heard of HbA1c   Diabetes care visit **    Dilated-eye **       Foot ** ++
----------------------------------------------------------------------------------------------------------------------------------------
Insulin use
 Insulin                                 93. 6&&                32.5                98.5 &&               73.2 &&           74.1 &&
 No insulin                              75.9                   21.8                89.3                  60.1              53.2
Age group (yrs)
 18-44 (Referent)                        81.0                   42.2                87.9                  53.5              45.6
 45-64                                   81.1                   26.6                91.4                  61.4              62.0
  >=65                                   85.3                   18.1 @@             96.9 @@               73.9 @@           68.5 @@
Sex
 Women                                   83.2                   30.3                93.0                  64.5              60.8
 Men                                     82.3                   20.6                92.7                  66.2              62.7
Race/Ethnicity ***
 White non-Hispanic                      86.0                   24.6                92.0                  65.6              59.3
 Black non-Hispanic                      77.3                   26.3                94.7                  63.2              66.7
Education level
 Less than high school                   79.7                   23.8                92.0                  60.3              60.4
diploma
 High school graduate or more            85.6                   27.8                93.4                  68.5              62.2
Health insurance coverage
 Yes                                     81.7                   24.7                93.0                  66.0              63.6
 No                                      91.0                   35.4                91.9                  58.4              46.4
Total                                    82.8                   25.9                92.9                  65.2              61.7
 (95% Confidence interval)           (77.6-87.9)            (19.9-31.9)          (89.5-96.2)          (58.8-71.6)       (54.6-68.7)
----------------------------------------------------------------------------------------------------------------------------------------
*   Per 100 persons aged >=18 years; 2-year average.
+   Data for 1994 and 1995 were aggregated.
&   Performed any self-monitoring of blood glucose.
@   Hemoglobin "A one C."
**  At least once during preceding year.
++  Among persons who visited a health-care professional for diabetes care during the preceding year.
&&  p<0.05, chi-square.
@@  p<0.05, test of trend.
*** Numbers for racial/ethnic groups other than black and white were too small for meaningful analysis.
========================================================================================================================================

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