Undiagnosed diabetes: Does limited access to healthcare explain high prevalence?

1
Undiagnosed diabetes Does limited access to
healthcare explain high prevalence?
Diane L. Manninen, Ph.D., Frederick B. Dong,
A.M., and Carlyn E. Orians, M.A., Centers for
Public Health Research and Evaluation, Battelle
Memorial Institute, 4500 Sand Point Way, NE 100,
Seattle, WA 98105-3949
Background
Table 1 Access and Use of Health Care by
Diabetes Status Using ADA Criteria
Table 2 Prevalence of Undiagnosed Diabetes by
Health Care Access and Utilization
Undiagnosed Diabetes Undiagnosed diabetes was
determined based upon the results of a fasting
plasma glucose test.

• Type 2 diabetes is a common and serious disease
  in the United States.
• Approximately 12.3 of U.S residents between the
  ages of 40 and 74 have diabetesone-third of
  which has not been diagnosed. The prevalence of
  diabetes (both diagnosed and undiagnosed) has
  been increasing.1 Prevalence of diabetes varies
  by age and race/ethnicity.1
• Undiagnosed diabetes is not a benign condition.
  Diabetes is associated with a number of
  microvascular complications (e.g., retinopathy,
  neuropathy, nephropathy) and individuals with
  diabetes are at an increased risk for blindness
  and renal failure. Among individuals who are
  diagnosed with Type 2 diabetes, 20 have
  background retinopathy and 10.5 have
  nephropathy present at the time of clinical
  diagnosis.2-4
• Early detection of diabetes can lead to earlier
  treatment through improved glycemic control.
  Better glycemic control can reduce the incidence
  and slow the progression of microvascular
  complications.5
• An opportunistic screening program for diabetes
  is cost-effective. 5 However, an opportunistic
  screening program requires access to health care
  and the utilization of health care services.

• Only those individuals who received their
  examination in the morning and fasted during the
  previous 9 to 24 hours (n5917).
• Applying criteria established by the American
  Diabetes Association (ADA), individuals with a
  fasting plasma glucose (FPG) of 126 mg/dl or more
  were considered to have undiagnosed diabetes
  (n231).6 World Health Organization (WHO)
  criteria7 were considered as an alternative
  definition of diabetes.

Table 3 Prevalence of Undiagnosed Diabetes by
Age, Health Insurance, and Utilization
Table 4 Odds Ratio for the Likelihood of
Undiagnosed Diabetes
Health Care Access and Utilization Measures
Several measures of health care access and
utilization were constructed from Health
Insurance and Health Services sections of the
NHANES III survey. These included dichotomous
variables indicating whether the individual had
Objective

• Health insurance (Medicare, Medicaid, Champus, or
  private health insurance).
• A particular place for care.
• A particular doctor for care.
• Seen a doctor in the past year.
• Seen a doctor two or more times in the past year.
• Been hospitalized in the past year.

• The objectives of the study were
• To compare the prevalence of undiagnosed diabetes
  by measures of health care access and
  utilization and
• To estimate the risk of undiagnosed diabetes by
  measures of health care access and utilization.

• Statistical Methods
• Stata statistical software8 was used to account
  for clustered sample design and sample weights.
• Two-sample t-tests were used to compare health
  care access and utilization measures of
  individuals with undiagnosed diabetes and those
  without diabetes.
• Multivariate logit analysis was used to estimate
  the risk of undiagnosed diabetes by measures of
  health care access and utilization.

Methods
Data Sources The prevalence of undiagnosed
diabetes was estimated using data from the Third
National Health and Nutrition Examination Survey
(NHANES III), a nationally representative sample
of the non-institutionalized U.S. population.
The NHANES III sample included 18,825 adults ages
20 and over.
Conclusions
Limited access to health care services does not
explain observed differences in undiagnosed
diabetes. Rather, the prevalence of undiagnosed
diabetes is as high or higher among those with
better access and higher utilization than among
those for whom access and utilization are lower.
References

• Socioeconomic and demographic data were obtained
  from the NHANES III household file and clinical
  blood chemistry values were obtained from the
  NHANES III laboratory file.
• Those with previously diagnosed diabetes were
  excluded from the analysis (n1,500), unless
  diabetes was diagnosed only during pregnancy.
• Individuals were excluded if they did not have
  valid test results for determining diabetes
  status.
• A total of 6,029 individuals were included in the
  analysis

• Even after controlling for age and
  race/ethnicity, the prevalence of undiagnosed
  diabetes is as high or higher among individuals
  with health care access compared with individuals
  whose access to health care is more limited.
• People who utilize the health care systemin
  particular among those who were hospitalizedare
  more likely to have undiagnosed diabetes.
• Higher utilization of health care services among
  people with undiagnosed diabetes is consistent
  with previous studies that have observed that
  higher utilization occurs eight years preceding
  diagnosis.9

1. Harris MI, Flegal KM, Cowie CC, et. al.
   Prevalence of diabetes, impaired fasting glucose
   and impaired glucose tolerance in U.S. adults.
   Diabetes Care. 1998 4518-530.
2. Harris M. Undiagnosed NIDDM clinical and public
   health issues. Diabetes Care. 1993 16642-652.
3. Harris MI, Modan M. Screening for NIDDM. Why is
   there no national program? Diabetes Care. 1994
   17440-444.
4. Wei M, Haffner S, Stern M. High fasting glucose
   as a predictor of total and cardiovascular
   disease (CVD) mortality in patients with NIDDM
   abstract. Diabetes. 1997 46(suppl 1)137A.
5. CDC Cost-Effectiveness Study Group. The
   cost-effectiveness of screening for Type 2
   diabetes. JAMA. 1998 2801757-1763.
6. American Diabetes Association. Report of the
   Expert Committee on the Diagnosis and
   Classification of Diabetes Mellitus (Position
   Statement). Diabetes Care. 1999 22(Suppl. 1)
   S5-19.
7. World Health Organization. Diabetes Mellitus
   Report of WHO Study Group. Geneva, World Health
   Org. 1985 (Tech Rep. Ser. No. 727).
8. Stata Corporation. Stata Statistical Software
   Release 7.0. College Station, Texas. 2001.
9. Nichols GA, Glauber HS, Brown JB. Type 2
   diabetes incremental medical care costs during
   the 8 years preceding diagnosis. Diabetes Care.
   2000 Nov23(11)1654-9.
10. Levetan CS, Passaro M, Jablonski K, Kass M,
    Ratner RE. Unrecognized diabetes among
    hospitalized patients. Diabetes Care. 1998
    21246-249.
11. Peters AL, Davidson MB, Schriger L, Hasselblad V.
    A clinical approach for the diagnosis of
    diabetes mellitus. JAMA. 1996
    276(15)1246-1262.

Therefore, there appears to be ample opportunity
for improvements in health outcomes, in a
cost-effective manner, through opportunistic
screening for Type 2 diabetes. Failure to screen
and diagnose people with diabetes may be due to
other factors.

• The fasting plasma glucose test may be
  inconvenient. The test is only valid if the
  patient has not eaten.
• Test results are often ignored. One-third of
  patients receiving surgical or medical services
  who were found to be hyperglycemic had no mention
  of diabetes in their medical records.10
• Other tests for diabetesfor example, a
  glycosylated hemoglobin (HbA1c) test, which is
  less sensitive to both food intake and physical
  activity levels11may be useful.