Home Glucose Monitoring

Thomas Higgins, M.D.

While measurements of glycated hemoglobin allows assessment of overall glucose control, home glucose monitoring allows the refinement of day to day diabetes control. We feel that profiling (a series of glucose measurements done on the same day) together with one or more profiles each week is most useful.

• The timing of individual glucose measurements in a profile depends on the specifics of a patient's diabetes treatment.
• The frequency of profiles depends upon the stability of the diabetes control over time.

In general, type 2 diabetes is more stable than type 1 and requires less frequent testing. The need for more or less testing in an individual patient will also change as their diabetes stability changes.

We feel that random glucose monitoring is much less useful than a profile. We recommend that you do random tests sparingly with two exceptions:

• test when you feel ill
• test before you turn the ignition key in your car

Profiles can be used to provide two categories of information relating to diabetes control: within day and day to day glucose variations.

WITHIN-DAY GLUCOSE VARIATIONS - The range over which the blood glucose varies within a day has been used to define one type of "unstable diabetes".

Consider the patient with a higher than desired glycated hemoglobin level, large postprandial rises in blood glucose, and precipitous falls before the next meal. Optimal therapy in this situation may require changes in both the nutritional prescription and the insulin regimen. As an example, a large meal containing a great deal of quickly absorbed carbohydrate that is low in soluble fiber can cause substantial postprandial hyperglycemia. Changing the overall distribution of carbohydrate (taking somewhat less with each meal and more with between meal snacks) and increasing the intake of soluble fiber should dampen the glycemic excursions after meals.

Altering the insulin regimen or oral diabetes drugs may also be helpful. For instance, large postprandial rises in blood glucose can be minimized by increasing the time between the injection of regular insulin (which begins to act within 20 to 30 minutes after subcutaneous injection) and the beginning of the meal. The use of a fast acting insulin like Humalog which has a much more rapid onset of action and larger peak effect than regular insulin, may obviate the need for a long lag-time between injecting insulin and eating in many patients.

DAY-TO-DAY GLUCOSE VARIATIONS - The extent to which the blood glucose varies at the same time each day is another useful parameter of overall glycemic control. This variability can be evaluated simply by scanning down columns of blood glucose measurements over several profiles. A frequent explanation for large daily fluctuations is an erratic lifestyle in terms of eating or exercise habits. These problems should be corrected before increasing the insulin regimen; if not, hypoglycemia will be more likely to occur. An additional explanation may be differences between week days and weekends or changes occur just before the onset of menses. In these situations, changes in insulin or other diabetes medications can be anticipated.

Newer methods of continuous glucose monitoring are becoming available and should prove very helpful in sorting out confusing glucose profiles. The Minimed company has recently gotten approval for it's monitor which gives relatively continuous monitoring for a maximum of 3 days.

In our practice, we will ask you to call us with your home glucose monitoring profiles so we can both help you adjust your medications and help you develop parameters for making your own adjustments. We are also available by phone to help with day to day issues of diabetes management.

For those persons using European Monitors, where the glucose values are expressed in mmol/L rather than the convention in the United States where glucose is expressed in mg/dl, I have included a conversion table below. Exact conversion is mg/dl x 0.0555 = mmol/L.