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Bethesda, MD -A recent study examining the trends in the control of risk factors for vascular disease among US individuals with diabetes mellitus has shown that the past decade has brought some improvement in the control of total cholesterol but nearly no change in controlling other risk factors for vascular disease.1
"In a nutshell, what we found was that there was significant improvement in the control of total cholesterol levels but there was really little to no change in blood pressure and glucose levels over time," senior investigator Dr Catherine C Cowie (National Institutes of Health, Bethesda, MD) told heartwire. "There still is a very large proportion of the diabetic population that remains uncontrolled."
While recent public-education programs have led to an increased awareness of the importance of controlling risk factors, Cowie said the findings reinforce the need for further public-health efforts.
The results of the study are published in the January 21, 2004 issue of the Journal of the American Medical Association.
Comparing NHANES III to NHANES 1999-2000
To examine trends in the control of risk factors for vascular disease among diabetic individuals, the investigators used data from the third National Health and Nutrition Examination Survey (NHANES III, n=1265) conducted between 1988 and 1994 and the 1999-2000 NHANES (n=441).
Specifically, the investigators, led by Dr Sharon H Saydah (National Institutes of Health, Bethesda, MD), compared control of glycosylated hemoglobin (HbA1c), blood pressure, and total serum cholesterol levels among adults with previously diagnosed diabetes between the two surveys to determine whether the control of risk factors for vascular disease has changed.
When you consider the cost of diabetes, all of these factors do not bode well for the future.
To define categories of desirable and undesirable HbA1c levels and blood pressure, investigators used the American Diabetes Association (ADA) standards of medical care for persons with diabetes. The ADA goal for the control of glycemia is HbA1c levels <7%, and it recommends additional treatment for individuals with HbA1c levels >8%. The ADA goal for the control of blood pressure is systolic BP <130 mm Hg and diastolic BP <80 mm Hg. Guidelines from the ADA and NCEP-ATP-III were used as goals to define levels of desirable and undesirable total cholesterol.
Adults aged 20 years and older who completed the NHANES interview and who self-reported diabetes as diagnosed by a physician were included in the study. Risk factors for vascular disease were reported for the overall population as well as by sex. Due to the small numbers of individuals diagnosed with diabetes in the second survey, the investigators were unable to stratify by age or race/ethnicity.
Levels of HbA1c, blood pressure, and total cholesterol among adults previously diagnosed with diabetes|
Risk factor |
NHANES III |
NHANES 1999-2000 |
p |
|
Mean HbA1c (%) | 7.6 | 7.8 | 0.30 |
|
- % subjects HbA1c <7.0% | 44.3 | 37.0 | 0.11 |
|
- % subjects HbA1c 7.0-8.0% | 19.2 | 25.8 | 0.07 |
|
- % subjects HbA1c >8.0% | 36.5 | 37.2 | 0.87 |
|
Total mean cholesterol (mg/dL) | 222.8 | 208.9 | <0.001 |
|
- % subjects >200 mg/dL | 66.1 | 51.8 | <0.001 |
|
Total mean systolic BP (mm Hg) | 137.9 | 134.8 | 0.04 |
|
Total mean diastolic BP (mm Hg) | 73.5 | 71.5 | 0.12 |
|
- % subjects with normal BP (SBP <130 mm Hg) and DBP <80 mm Hg) | 29.0 | 35.8 | 0.10 |
|
- % subjects with hypertension (SBP >140 mm Hg or DBP >90 mm Hg) | 42.9 | 40.4 | 0.56 |
Overall, the percentage of adults with diagnosed diabetes in NHANES 1999-2000 who achieved target levels of HbA1c, blood pressure, and total cholesterol was 7.3%, compared with 5.2% of those who attained recommended target levels of these risk factors a decade earlier.
Cowie told heartwire that the cost of providing care for diabetes and its complications is rapidly increasing, with recent US estimates pegged at $132 billion annually.
Participants in the recent NHANES were diagnosed with diabetes at an earlier age, corresponding to significantly longer duration of disease. Moreover, the obesity epidemic spreading across the US is also seen in diabetic patients, with an increase in BMI of adults with diagnosed diabetes. Despite these shifts, the longer duration of disease and increase in BMI did not correspond to higher levels of glycemia, blood pressure, and cholesterol, said Cowie.
"While these factors may have gotten worse, we didn't actually find a worsening of the risk factors for vascular disease, possibly due to the fact that there is now more intensive treatment. So maybe there is a positive message in this," said Cowie. "However, control is still not good. When you consider the cost of diabetes, all of these factors do not bode well for the future. We have to do a better job in getting the message out."
The investigators report that one of the limitations of the study was the small number of participants with diagnosed diabetes in NHANES 1999-2000, which limits analyses by subgroups. While the cross-sectional design of the study allowed investigators to draw inferences on trends among diabetic participants, firm conclusions shouldn't be drawn on temporal relationships of the observations, they add.
