Home Monitoring of Glucose and Blood Pressure

Am Fam Physician. 2007 Jul 15;76(2):255-260.

ACF  This article exemplifies the AAFP 2007 Annual Clinical Focus on management of chronic illness.

  Patient information: See related handouts on home monitoring of blood pressure and home monitoring of blood sugar, written by the authors of this article.

Home monitoring of blood glucose and blood pressure levels can provide patients and physicians with valuable information in the management of diabetes mellitus and hypertension. Home monitoring allows patients to play an active role in their care and may improve treatment adherence and clinical outcomes. Glucose meters currently on the market produce results within 15 percent of serum blood glucose readings and offer a variety of features. Although the data are somewhat conflicting, home glucose monitoring has been associated with improved glycemic control and reduced long-term complications from diabetes. These effects are more pronounced in patients who take insulin. Home blood pressure values predict target organ damage and cardiovascular outcomes better than values obtained in the office. Home blood pressure measurements are also effective at detecting borderline hypertension and monitoring the effectiveness of antihypertensive drugs. Validated arm cuffs are the preferred blood pressure devices for home use. Information from home monitoring should always be used in conjunction with that from regular office visits and other data to make appropriate therapeutic decisions.

Home monitoring of blood glucose and blood pressure levels can provide the patient and physician with valuable information for disease management. Because a variety of home monitoring devices are available, appropriate selection and use can be a daunting task. This article reviews devices for home monitoring of glucose and blood pressure and discusses their clinical utility.

SORT: KEY RECOMMENDATIONS FOR PRACTICE

Clinical recommendation Evidence rating References

Patients with type 1 diabetes should self-monitor blood glucose three or more times a day.

C

9

Glucose should be monitored more frequently during insulin dose adjustments.

C

8

Patients with hypertension should monitor their blood pressure at home because it correlates well with target organ damage and cardiovascular mortality. It also can be used to monitor drug effectiveness.

B

17

Home blood pressure measurement should be performed twice in the morning and twice in the evening for at least three days to determine the patient's usual blood pressure.

C

17


A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, see page 176 or http://www.aafp.org/afpsort.xml.

SORT: KEY RECOMMENDATIONS FOR PRACTICE

View Table

SORT: KEY RECOMMENDATIONS FOR PRACTICE

Clinical recommendation Evidence rating References

Patients with type 1 diabetes should self-monitor blood glucose three or more times a day.

C

9

Glucose should be monitored more frequently during insulin dose adjustments.

C

8

Patients with hypertension should monitor their blood pressure at home because it correlates well with target organ damage and cardiovascular mortality. It also can be used to monitor drug effectiveness.

B

17

Home blood pressure measurement should be performed twice in the morning and twice in the evening for at least three days to determine the patient's usual blood pressure.

C

17


A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, see page 176 or http://www.aafp.org/afpsort.xml.

Glucose Monitoring

Although there is no universal standard for accuracy of glucose meters, several groups have defined acceptable ranges.14 The U.S. Food and Drug Administration (FDA) requires glucose meters to produce self-monitoring results within 20 percent of a reference measurement but recommends results within 15 percent4; the FDA has stated that future meters should achieve results within 10 percent of reference at serum glucose concentrations of 30 to 400 mg per dL (1.7 to 22.2 mmol per L). The American Diabetes Association (ADA) recommends that meters produce readings within 5 percent of laboratory values.1 All meters currently on the market are considered to be clinically accurate in that they at least meet the FDA standard, although it is important to remember that they are not as accurate as a standard laboratory test.5,6 Given this broad range of possible error, making treatment decisions based solely on self-monitoring of blood glucose (SMBG) is not advised.

Glucose meters are most accurate when used properly.7 Thus, educating patients on proper use and what to do with the results is vital. Although the exact procedure for using a meter varies by product, potential pitfalls are similar. Common errors include poor maintenance (e.g., soiled meter), using expired test strips, obtaining an inadequate sample size, and failing to calibrate the meter.

CLINICAL UTILITY

Uses of SMBG data include identifying and treating hyper- and hypoglycemia; making decisions about food intake or medication adjustment when exercising; determining the effect of ingested food on blood glucose; and managing glucose fluctuations resulting from illness.8 Although the data are somewhat conflicting, larger, better-designed trials have shown that SMBG improves glycemic control when the results are used to adjust therapy.6 However, the data for reducing long-term complications are more conclusive for patients on insulin therapy.

Although the optimal frequency of monitoring is unknown, the ADA recommends SMBG three or more times a day for patients with type 1 diabetes.9 Patients with type 2 diabetes still benefit from at least periodic monitoring. Ultimately, the frequency and timing of SMBG should be determined by how the data will be used.8 SMBG can assist the patient and physician with adjusting diet and medications and maintaining appropriate glucose control. More frequent monitoring is beneficial during insulin dose adjustments.8 Postprandial monitoring is important to identify the effect of various foods on glucose levels and to monitor the effects of preprandial medications. Other factors, such as desire for tight control and current degree of control, will influence frequency of monitoring.

METER SELECTION

A number of glucose meters are available, with new models being released each year. Although home glucose meters use whole-blood samples, nearly all are plasma calibrated so that the results reflect plasma glucose. This allows home values to be compared directly to laboratory values. Glucose meters are largely differentiated based on their features. These include blood sample size required, test time, memory capability, ability to download results into data management software, and ability to perform alternate site testing (e.g., forearm). Meter selection should be based primarily on features desired by the patient (Table 1).

Table 1

Considerations for Glucose Meter selection

Feature Clinical advantages

Smaller sample size requirement

Less painful, permits alternate site testing

Alternate site testing

Less discomfort for patients who use fingertips regularly (e.g., for typing)

Results in less than 15 seconds

Increased convenience

Table 1   Considerations for Glucose Meter selection

View Table

Table 1

Considerations for Glucose Meter selection

Feature Clinical advantages

Smaller sample size requirement

Less painful, permits alternate site testing

Alternate site testing

Less discomfort for patients who use fingertips regularly (e.g., for typing)

Results in less than 15 seconds

Increased convenience

Newer technology has led to the development of continuous glucose meters that measure glucose in subcutaneous interstitial fluid and reflect changes relatively quickly. However, continuous monitors are not easily used on a long-term basis, and their current clinical utility is somewhat limited. Table 2 provides a comparison of commonly used glucose meters. Prices of most glucose meters and strips are comparable. However, patients often can purchase the meter for little or no cost after rebates. The long-term expenses come from the strips and other supplies. A few meters offer more advanced features, such as the ability to enter information (e.g., medication doses, carbohydrate intake, exercise) and voice prompts for the visually impaired.

Table 2

Common Glucose Meters

Glucose meter Approximate cost ($)*† Sample size Comments

Alternate site testing, test time ≤ 15 seconds

Accu-Chek Active

20 (meter) 0.60 (per test)

1 μL

Able to download, memory

Accu-Chek Aviva

75 (meter) 1.00 (per test)

0.6 μL

Able to download, memory, larger test strip for easier handling

Accu-Chek Compact Plus

78 (meter) 1.00 (per test)

1.5 μL

Able to download, memory, uses 17-strip drum to avoid handling strips

Ascensia Contour

75 (meter) 0.93 (per test)

0.6 μL

Able to download, memory

FreeStyle

77 (meter) 0.97 (per test)

0.3 μL

Able to download

FreeStyle Flash

75 (meter) 0.97 (per test)

0.3 μL

Able to download, compact meter

OneTouch InDue

110 (meter) 0.98 (per test)

1 μL

Combination meter and insulin pen for use with Novo PenFill

OneTouch Ultra2

70 (meter) 0.98 (per test)

1 μL

Able to download, memory

OneTouch UltraSmart

91 (meter) 0.98 (per test)

1 μL

Combination meter and electronic logbook

ReliOn Ultima (sold only at Wal-Mart stores)

9 (meter) 0.43 (per test)

0.6 μL

Memory

TrueTrack Smart (sold as generic meter at pharmacies under pharmacy name)

18 (meter) 0.52 (per test)

1 μL

Memory

Alternate site testing, test time > 15 seconds

Ascensia Breeze

60 (meter) 0.88 (per test)

2.5 to 3.5 μL

Able to download, memory, uses 10-strip disk to avoid handling strips

Ascensia DEX 2

88 (meter) 0.88 (per test)

2.5 to 3.5 μL

Able to download, memory, uses 10-strip disk to avoid handling strips

Ascensia Elite and Elite XL

50 (Elite meter)

2 μL

No buttons, easy to use, XL meter has larger memory

70 (Elite XL meter) 0.88 (per test)

No alternate site testing, test time ≥30 seconds

Accu-Chek Advantage

69 (meter) 0.90 (per test)

4 or 9 μL (depending on strip used)

Able to download, memory

Accu-Chek Complete

120 (meter) 0.90 (per test)

4 or 9 μL (depending on strip used)

Able to download, memory, stores information on insulin doses, carbohydrates, exercise, laboratory results

Accu-Chek Voicemate

480 (meter) 0.90 (per test)

4 μL

Memory, voice prompts

OneTouch Basic

57 (meter) 0.92 (per test)

10 μL

Memory, reports whole blood glucose

OneTouch SureStep

78 (meter) 1.00 (per test)

10 μL

Able to download, memory


†— Price per test reflects test strip cost only and does not include additional items such as control solutions and lancets.

Table 2   Common Glucose Meters

View Table

Table 2

Common Glucose Meters

Glucose meter Approximate cost ($)*† Sample size Comments

Alternate site testing, test time ≤ 15 seconds

Accu-Chek Active

20 (meter) 0.60 (per test)

1 μL

Able to download, memory

Accu-Chek Aviva

75 (meter) 1.00 (per test)

0.6 μL

Able to download, memory, larger test strip for easier handling

Accu-Chek Compact Plus

78 (meter) 1.00 (per test)

1.5 μL

Able to download, memory, uses 17-strip drum to avoid handling strips

Ascensia Contour

75 (meter) 0.93 (per test)

0.6 μL

Able to download, memory

FreeStyle

77 (meter) 0.97 (per test)

0.3 μL

Able to download

FreeStyle Flash

75 (meter) 0.97 (per test)

0.3 μL

Able to download, compact meter

OneTouch InDue

110 (meter) 0.98 (per test)

1 μL

Combination meter and insulin pen for use with Novo PenFill

OneTouch Ultra2

70 (meter) 0.98 (per test)

1 μL

Able to download, memory

OneTouch UltraSmart

91 (meter) 0.98 (per test)

1 μL

Combination meter and electronic logbook

ReliOn Ultima (sold only at Wal-Mart stores)

9 (meter) 0.43 (per test)

0.6 μL

Memory

TrueTrack Smart (sold as generic meter at pharmacies under pharmacy name)

18 (meter) 0.52 (per test)

1 μL

Memory

Alternate site testing, test time > 15 seconds

Ascensia Breeze

60 (meter) 0.88 (per test)

2.5 to 3.5 μL

Able to download, memory, uses 10-strip disk to avoid handling strips

Ascensia DEX 2

88 (meter) 0.88 (per test)

2.5 to 3.5 μL

Able to download, memory, uses 10-strip disk to avoid handling strips

Ascensia Elite and Elite XL

50 (Elite meter)

2 μL

No buttons, easy to use, XL meter has larger memory

70 (Elite XL meter) 0.88 (per test)

No alternate site testing, test time ≥30 seconds

Accu-Chek Advantage

69 (meter) 0.90 (per test)

4 or 9 μL (depending on strip used)

Able to download, memory

Accu-Chek Complete

120 (meter) 0.90 (per test)

4 or 9 μL (depending on strip used)

Able to download, memory, stores information on insulin doses, carbohydrates, exercise, laboratory results

Accu-Chek Voicemate

480 (meter) 0.90 (per test)

4 μL

Memory, voice prompts

OneTouch Basic

57 (meter) 0.92 (per test)

10 μL

Memory, reports whole blood glucose

OneTouch SureStep

78 (meter) 1.00 (per test)

10 μL

Able to download, memory


†— Price per test reflects test strip cost only and does not include additional items such as control solutions and lancets.

Blood Pressure Monitoring

Electronic devices are available to measure blood pressure at the arm, wrist, or finger. Published data evaluating the accuracy of specific electronic blood pressure monitors are limited. However, several organizations have established standards for accuracy.1013  Devices available in the United States that are known to meet these criteria are listed in Table 3. Clinical evaluations of wrist and finger devices have revealed that these instruments are considerably less accurate than their arm (brachial artery) counterparts, with finger monitors being the least accurate.1416 Thus, arm monitors are preferred over wrist or finger monitors.

Table 3

Validated Electronic Arm Home Blood Pressure Monitors

Monitor Approximate cost ($)*† Use if patient has arrhythmia? Memory feature? Comments

Basic models

LifeSource UA-704

25

No

No

Semiautomatic, compact

Omron HEM-432C

25

No

Yes

Semiautomatic

LifeSource UA-767

50

No

No

Automatic

LifeSource UA-767 Plus

58

Yes

Yes

Automatic, latex free

Models with extra features

LifeSource UA- 787AC

62

Yes

Yes

Reminder alarms, latex free

LifeSource UA-787EJ

65

Yes

Yes

Averages, reminder alarms, easy-fit cuff

LifeSource UA-774

67

Yes

Yes

Dual memory for two users, latex free

Omron HEM-712C

70

Yes

Yes

Compact

LifeSource UA-767T

75

No

Yes

Voice announcement of results

Omron HEM-711AC

80

Yes

Yes

Includes AC adapter

Omron HEM-705CP

100

Yes

Yes

Includes printer

Omron HEM-780

100

Yes

Yes

Includes AC adapter, contoured cuff

Omron HEM-773AC

120

Yes

Yes

Includes AC adapter, contoured cuff


†— Prices given are for medium-size cuff; large cuffs, where available, are slightly more expensive.

‡— All are automatic.

Table 3   Validated Electronic Arm Home Blood Pressure Monitors

View Table

Table 3

Validated Electronic Arm Home Blood Pressure Monitors

Monitor Approximate cost ($)*† Use if patient has arrhythmia? Memory feature? Comments

Basic models

LifeSource UA-704

25

No

No

Semiautomatic, compact

Omron HEM-432C

25

No

Yes

Semiautomatic

LifeSource UA-767

50

No

No

Automatic

LifeSource UA-767 Plus

58

Yes

Yes

Automatic, latex free

Models with extra features

LifeSource UA- 787AC

62

Yes

Yes

Reminder alarms, latex free

LifeSource UA-787EJ

65

Yes

Yes

Averages, reminder alarms, easy-fit cuff

LifeSource UA-774

67

Yes

Yes

Dual memory for two users, latex free

Omron HEM-712C

70

Yes

Yes

Compact

LifeSource UA-767T

75

No

Yes

Voice announcement of results

Omron HEM-711AC

80

Yes

Yes

Includes AC adapter

Omron HEM-705CP

100

Yes

Yes

Includes printer

Omron HEM-780

100

Yes

Yes

Includes AC adapter, contoured cuff

Omron HEM-773AC

120

Yes

Yes

Includes AC adapter, contoured cuff


†— Prices given are for medium-size cuff; large cuffs, where available, are slightly more expensive.

‡— All are automatic.

CLINICAL UTILITY

Office-based blood pressure measurements have been shown to result in higher values than those recorded at home.17 Studies have found variations of 9 to 23 mm Hg in systolic blood pressure and diastolic differences of 3 to 10 mm Hg.18 The most recent report from the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) defines home blood pressure values consistently greater than 135/85 mm Hg as hypertensive.19 The differences in systolic pressure between home and office blood pressure measurements increase with age and degree of anxiety during office visits (known as “white coat” hypertension). These differences also tend to be greater in men and in patients not taking antihypertensive medication.

A systematic review concluded that, compared with office monitoring, home monitoring is better at predicting target organ damage and cardiovascular mortality, predicting sustained hypertension in patients with borderline hypertension, and can be used to monitor drug effectiveness.17 This evidence is based on the use of validated blood pressure monitors. Although there are no evidence-based recommendations on frequency of home blood pressure measurements, it has been suggested that the minimal number of measurements to obtain an accurate assessment of a patient's usual blood pressure should be four times per day (twice in the morning and twice in the evening) for three consecutive days.17

MONITOR SELECTION

Although there are limited comparative data on specific blood pressure monitors, home monitoring offers several advantages in addition to its correlation with outcomes and drug effectiveness. It eliminates the white coat effect, allows for multiple readings, and may improve patient awareness and compliance with treatment. There are, however, a few limitations. Some home devices may not be appropriate in obese patients (because of limited cuff sizes), patients with arrhythmias or preeclampsia, and patients in whom vascular stiffening is suspected.17 In a recent randomized controlled trial, adjustment of antihypertensive medications based solely on home monitoring led to less-intensive drug treatment and poorer blood pressure control than usual care.20 Medication adjustments should incorporate values from home and office monitoring.

Electronic blood pressure models are relatively easy to use and display a digital readout. They may be semiautomatic (i.e., patient inflates and deflates cuff) or fully automatic (i.e., cuff inflates and deflates with the press of a button), although both types automatically measure the blood pressure. Electronic blood pressure readings correlate well with the auscultatory method.21  Despite the relative ease of using electronic blood pressure monitors, failure to follow protocol can lead to erroneous results. Table 4 outlines the recommended protocol for home blood pressure measurement.

Table 4

Recommended Protocol for Home Blood Pressure Monitoring

Avoid exercise, caffeine, and other stimulants 30 minutes before measurement

Avoid restrictive clothing

Use an appropriately sized cuff

Rest quietly before and during blood pressure measurement

Position arm at heart level

Do not talk while the machine is measuring the blood pressure

Table 4   Recommended Protocol for Home Blood Pressure Monitoring

View Table

Table 4

Recommended Protocol for Home Blood Pressure Monitoring

Avoid exercise, caffeine, and other stimulants 30 minutes before measurement

Avoid restrictive clothing

Use an appropriately sized cuff

Rest quietly before and during blood pressure measurement

Position arm at heart level

Do not talk while the machine is measuring the blood pressure

The Authors

JAMES R. TAYLOR, PharmD, CDE, is a clinical assistant professor in the Department of Pharmacy Practice at the University of Florida College of Pharmacy, Gainesville. He received his pharmacy degree from Ohio Northern University, Ada, and completed a pharmacy practice residency at the Veterans Affairs Medical Center, Huntington, W.Va., and a family medicine residency at the University of Florida.

KENDALL M. CAMPBELL, MD, is a clinical assistant professor in the Department of Community Health and Family Medicine and assistant dean for minority affairs at the University of Florida College of Medicine, Gainesville. He received his medical degree from the University of Florida, and completed his residency training at Tallahassee (Fla.) Memorial Healthcare.

Address correspondence to James R. Taylor, PharmD, CDE, University of Florida College of Pharmacy, P.O. Box 100486, Gainesville, FL 32610-0486 (e-mail: jtaylor@cop.ufl.edu). Reprints are not available from the authors.

Author disclosure: Nothing to disclose.

REFERENCES

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2. Chmielewski SA. Advances and strategies for glucose monitoring [Published correction appears in Am J Clin Pathol 1996;105:134]. Am J Clin Pathol. 1995;104(4 suppl 1):S59–71.

3. Clarke WL, Cox D, Gonder-Frederick LA, Carter W, Pohl SL. Evaluating clinical accuracy of systems for self-monitoring of blood glucose. Diabetes Care. 1987;10:622–8.

4. Review criteria assessment of portable invasive blood glucose monitoring in vitro diagnostic devices using glucose oxidase, dehydrogenase or hexokinase methodology. Rockville, Md.: U.S. Food and Drug Administration, 1996.

5. American Diabetes Association. Blood glucose monitoring and data management systems. Diabetes Forecast. 2006;59(suppl 1):S42–59.

6. Saudek CD, Derr RL, Kalyani RR. Assessing glycemia in diabetes using self-monitoring blood glucose and hemoglobin A1c. JAMA. 2006;295:1688–97.

7. Fleming DR. Accuracy of blood glucose monitoring for patients: what it is and how to achieve it. Diabetes Educ. 1994;20:495–8,500.

8. Peragallo-Dittko V. Monitoring. In: Franz MJ, ed. A Core Curriculum for Diabetes Education. 4th ed. Chicago, Ill.: American Association of Diabetes Educators, 2001: 153–72.

9. Standards of medical care in diabetes. Diabetes Care. 2006;28:S4–42.

10. Electronic or automated sphygmomanometers. Arlington, Va.: Association for the Advancement of Medical Instrumentation, 1992:1–40.

11. O'Brien E, Petrie J, Littler W, de Swiet M, Padfield PL, O'Malley K, et al. The British Hypertension Society protocol for the evaluation of automated and semiautomated blood pressure measuring devices with special reference to ambulatory systems. J Hypertens. 1990;8:607–19.

12. White WB, Berson AS, Robbins C, Jamieson MJ, Prisant LM, Roccella E, et al. National standard for measurement of resting and ambulatory blood pressures with automated sphygmomanometers. Hypertension. 1993;21:504–9.

13. O'Brien E, Pickering T, Asmar R, Myers M, Parati G, Staessen J, et al. Working Group on Blood Pressure Monitoring of the European Society of Hypertension International Protocol for validation of blood pressure measuring devices in adults. Blood Press Monit. 2002;7:3–17.

14. Kikuya M, Chonan K, Imai Y, Goto E, Ishii M, for the Research Group to Assess the Validity of Automated Blood Pressure Measurement Devices in Japan. Accuracy and reliability of wrist-cuff devices for self-measurement of blood pressure. J Hypertens. 2002;20:629–38.

15. Rotch AL, Dean JO, Kendrach MG, Wright SG, Woolley TW. Blood pressure monitoring with home monitors versus mercury sphygmomanometer. Ann Pharmaco-ther. 2001;35:817–22.

16. Zweiker R, Schumacher M, Fruhwald FM, Watzinger N, Klein W. Comparison of wrist blood pressure measurement with conventional sphygmomanometry at a cardiology outpatient clinic. J Hypertens. 2000;18:1013–8.

17. Verberk WJ, Kroon AA, Kessels AG, de Leeuw PW. Home blood pressure measurement: a systematic review. J Am Coll Cardiol. 2005;46:743–51.

18. Pickering TG, James GD. Some implications of the differences between home, clinic and ambulatory blood pressure in normotensive and hypertensive patients. J Hypertens Suppl. 1989;7:S65–72.

19. National Heart, Lung, and Blood Institute. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7 Express). Accessed January 19, 2007, at: http://www.nhlbi.nih.gov/guidelines/hypertension/jncintro.htm.

20. Staessen JA, Den Hond E, Celis H, Fagard R, Keary L, Vandenhoven G, et al., for the Treatment of Hypertension Based on Home or Office Blood Pressure (THOP) Trial Investigators. Antihypertensive treatment based on blood pressure measurement at home or in the physician's office: a randomized controlled trial. JAMA. 2004;291:955–64.

21. Pickering T. Recommendations for the use of home (self) and ambulatory blood pressure monitoring. Am J Hypertens. 1996;9:1–11.


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