Self-monitoring of blood glucose: Advice for providers and patients

WHETHER AND HOW OFTEN TO MONITOR

In clinical practice, advice about whether patients should monitor their blood glucose levels and how often to do it depends on the type of diabetes therapy, the need to titrate the dose or change the regimen, and the patient’s preferences, dexterity, and visual acuity. The frequency of testing also often depends on financial considerations and insurance coverage.

In patients with type 1 diabetes and insulin-treated type 2 diabetes, the role of glucose self-monitoring is clear. The American Diabetes Association (ADA) recommends that patients receiving multiple insulin injections daily or on an insulin pump measure their blood glucose at least before meals and snacks, occasionally after meals, at bedtime, before exercise, when they suspect their blood glucose level is low, after treating low blood glucose until they are normoglycemic, and before critical tasks such as driving.²

The Diabetes Control and Complications Trial (DCCT)³ and the DCCT/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study⁴ showed that intensive insulin therapy effectively delays the onset and slows the progression of microvascular and macrovacscular disease. Self-monitoring of blood glucose is an integral part of intensive insulin therapy, allowing for dose adjustments based on immediate blood glucose readings, thereby reducing the risks of hyperglycemia and hypoglycemia.

For patients taking a single daily dose of basal insulin, fasting blood glucose values are often used to titrate the basal insulin dose.³

Patients with type 2 diabetes on oral hypoglycemic agents such as sulfonylureas and meglitinides are at risk of hypoglycemia. Although a review of the literature could find no studies to support recommendations for specific testing frequency for patients taking these medications, it stands to reason that the potential for hypoglycemia would indicate a clear need for regular self-monitoring. Checking the blood glucose once or twice daily, typically fasting, 2 hours after the largest meal or at bedtime, provides useful data points for the patient and the provider. As with patients on insulin, testing before driving also reduces the risk of a motor vehicle accident caused by hypoglycemia.

In any patient who is testing one or two times per day, staggering the testing time on different days can give valuable insight into glucose control at different times of day, including after meals and at night.

In patients on nonintensive regimens and at low risk of hypoglycemia, glucose self-monitoring may be less critical. Nonintensive regimens with a low risk of hypoglycemia include diet and exercise alone and diet and exercise with a medication that is not insulin or an insulin secretagogue. In these cases, self-monitoring is often not seen as clinically useful or cost-effective, and hemoglobin A_1c is used as a marker.

Admittedly, few randomized controlled trials have been done in which patients were treated according to identical protocols except for glucose self-monitoring, but outcomes from the published studies support the use of structured self-monitoring of blood glucose for improvement in clinical outcomes and quality of life when self-monitoring is incorporated into a comprehensive management plan.^5–9 By providing feedback, self-monitoring encourages patients to actively participate in controlling and treating their disease. It helps them to recognize the impact of blood glucose on their own self-management decisions in the areas of diet, exercise, stress management, and medications. Therefore, the ADA recommends that healthcare providers encourage their patients to perform self-monitoring even if on nonintensive regimens. For these patients, checking even two or three times per week can help them to learn about the factors that affect their blood glucose.²

BLOOD GLUCOSE TARGETS

The ADA² recommends the following glycemic goals for most nonpregnant adults:

• Fasting and premeal—80–130 mg/dL

• 2-hour postprandial—less than 180 mg/dL

• Bedtime—100–150 mg/dL.

However, diabetes management should be individualized on the basis of age and other comorbidities. For example, geriatric patients who have frequent episodes of hypoglycemia are prone to more harm than benefit from intensifying therapy to achieve these targets. Consequently, they may be candidates for more relaxed goals to avoid episodes of dangerous hypoglycemia.

When discussing blood glucose targets, an important but often overlooked concern is how the patient perceives the results. Providers and patients alike often describe readings as “good” or “bad.” This interpretation can lead to feelings of disappointment and failure in the patient and frustration in the provider. Instead, high blood glucose readings should be viewed as a way to identify opportunities for change. Patients may be more willing to check and even log their blood glucose levels if they see this information as an instrument to be used in the collaborative relationship with their provider.

CHOOSING A BLOOD GLUCOSE METER

Barring any special needs of the patient, meters are often selected on the basis of the patients’ insurance coverage for self-monitoring supplies (test strips and lancets), because of the high cost of test strips when purchased out-of-pocket. Meters themselves are usually relatively inexpensive, since the manufacturers commonly give them away as free samples to providers, who pass them along to patients. They also can often be purchased using coupons at a significant discount.

Without insurance coverage, test strips can cost $0.83 to $1.76 per strip for the most popular brands of meters. For patients without insurance coverage for supplies, the lowest-cost test strips currently available are for the ReliOn Prime Blood Glucose Monitoring System (ie, meter) sold at Walmart. Although ReliOn meters are not given out as samples in providers’ offices, the manufacturer’s suggested retail price is $16.24. More importantly, the suggested retail price for ReliOn Prime test strips is $9.00 for a bottle of 50 strips, or $0.18 per strip.¹⁰

METER ACCURACY

Even though patients and providers use glucose self-monitoring results to make important decisions about diabetes management, the meters have limitations in accuracy. Accuracy comparisons from third-party sources are rare due to the cost of accuracy testing. However, the US Food and Drug Administration (FDA) requires all home glucose meters to meet accuracy standards set by the International Organization for Standardization (ISO). Currently, the FDA uses ISO standard 15197:2003, but ISO has published a revision, ISO standard 15197:2013, with stricter guidelines that have yet to be adopted by the FDA.^10,11 Current and future guidelines are shown in Table 1.¹⁰

In addition to variations in accuracy that are deemed acceptable by the FDA, there are other more controllable factors that can further affect the accuracy of glucose meter results. Expired test strips, unwashed hands, poor sampling technique, storage of test strips in extreme temperatures or humidity, and a low hematocrit level all can cause inaccurate readings.

If the patient has a low hematocrit, consider recommending a meter proven to have stable performance in the setting of low hematocrit. These meters are highlighted in a 2013 study by Ramljak et al.¹²

LANCETS, LANCING DEVICES, AND TECHNIQUES

Along with a variety of meters, patients also have an array of lancets and lancing devices from which to choose. Many patients use the brand of lancet device and lancets that come in their meter starter kit, but they can use other brands if desired. For cost-conscious patients, lancets are significantly more affordable than test strips, even for those without insurance coverage. Prices can be as low as $0.03 per lancet for some store-brand 33-gauge lancets. Name-brand lancets are more expensive than store-brand, but at $0.06 to $0.16 per lancet, many patients will even find these to be affordable if they must pay out of pocket.

Special needs may also prompt patients to choose a different lancet device than the one that came with their meter. For patients who have poor dexterity or are afraid to look at needles, the Accu-Chek FastClix lancing device uses drums with six preloaded lancets, eliminating the need to see and handle individual lancets. The FastClix device is included in the starter kits for the Accu-Chek Nano and Accu-Chek Connect meters and can also be ordered separately at pharmacies.

LOGGING BLOOD GLUCOSE READINGS

Although many meters can automatically transfer their data to mobile devices or computers, patients are still encouraged to log their glucose readings manually. Not only does this give feedback to the provider in the event that the downloading software is not available in that provider’s office, it also allows patients to learn how to identify patterns in their readings and make changes in their diabetes self-management.

In the past, all logging was done on paper forms or in log books, but today’s technology offers other options. Several meters offer downloading software for home use that displays the data in a usable format. Some smartphone apps allow patients to enter glucose readings and other useful diabetes information such as food intake and exercise. Below are examples of smart-phone apps that can help patients track glucose levels and much more:

• mySugr (iPhone and Android)

• Glucose Buddy (iPhone and Android)

• OnTrack Diabetes (Android)

• Glucool Diabetes (Android) (also available in a premium version).

• Glooko (iPhone and Android). This app requires purchase of a compatible cable to connect the patient’s phone to the meter, which then allows readings to be transferred directly to the app.

THE ROLE OF THE CERTIFIED DIABETES EDUCATOR

One of the most useful resources available to providers is the assistance of a certified diabetes educator, who can teach a patient the basic operation of a blood glucose meter and educate the patient on all topics discussed in this article and more.

Certified diabetes educators are instrumental in helping patients understand blood glucose targets, the rationale for glucose self-monitoring, logging, pattern management, special features in meters, control testing, and alternate-site testing, and using the results of testing to make meaningful changes in how they self-manage their diabetes. Education should include discussions about topics such as meal planning, exercise, and medications to help patients fully grasp the impact of their daily decisions on their blood glucose control.