By Richard S. Beaser, M.D.
Chapter 3: Monitoring Diabetes: The Importance of Self-Monitoring of Blood Glucose and Glycohemoglobin Measurements (Overview)
Self-monitoring (SMBG) is important for a number of reasons. A person with diabetes must always know his or her blood glucose value at any given time in order to prevent the potential dangers of acutely high or low levels. For those using physiologic insulin replacement therapy (in the past referred to as “intensive insulin therapy” and referring to multiple daily injections or pump therapy) knowing the current level is essential if adjustments in insulin doses are to be made to target normoglycemia. In addition, for those patients using antidiabetes medication therapies, the glucose patterns can suggest the predominant underlying pathophysiology and thus lead to a more accurate medication selection. A further advantage: self-monitoring occurs during the patient’s routine daily activities rather than in an artificial hospital setting as was the necessity just a few decades ago.
Perhaps equally important, but less obvious, is that SMBG more effectively engages the patient in his or her own self-care. It is imperative that people who are self-monitoring know what to do with the results of their glucose checking so that they can take active steps to improve their control. They should be given instructions on how to interpret their results, what they can do themselves in response to the results, and when they should call for help. Patient education is a critical component of every diabetes treatment plan. No patient should go in for a routine interval visit with a healthcare provider with a list of self-monitoring results that are significantly suboptimal, without having taken some corrective action during the interval between visits.
Goals of diabetes treatment need to be defined in terms of self-monitoring results. Ideal targets for fasting, prelunch and presupper, and postprandial glucose tests should be defined. Acceptable levels should also be determined, as not all values are likely to be ideal. In addition, the degree of variability should also be reviewed (see Chapter 2, Tables 2-4, 2-5, 2-6).
In sum, there are a few basic reasons why SMBG should be performed:
- To provide data about glucose patterns that can be used by the healthcare team, working with the patient, to make treatment
- To provide data with which patients themselves can make daily decisions on treatment adjustments (in a physiologic insulin replacement program, for example)
- To provide feedback on how effectively the individual is adhering to daily self-care routines, including medical nutrition therapy, physical activity, and medication use
Glycohemoglobin, or A1C, goals are also a useful part of treatment monitoring beyond their obvious reflection of average glucose level and complication risk. These measurements can be reported to patients, providing positive feedback if the values reflect improvement or goals achieved, and conversely, indicating the need to strive for better control if they do not reflect improvement (see Chapter 2, Table 2-5).
These two means of monitoring diabetes, SMBG and glycohemoglobin or A1C measurements, are not meant to be used as a substitute for one another. They reflect different components of diabetes treatment and thus should complement one another.
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