How is diabetic treatment monitored at home?

How is diabetic treatment monitored at home?

The goal of diabetic therapy is to control blood glucose levels and prevent the complications of diabetes. Glucose levels are lowered into a normal range, if possible, but it is important not to reduce the levels to abnormally low levels which can cause symptoms such as sweating, increased heart rate, and even loss of consciousness. Therefore, it is necessary not only to treat the diabetes but to monitor the effects of treatment on blood glucose levels to avoid overtreatment or undertreatment of the diabetes.

There are two types of tests for blood glucose monitoring in the home. The first type uses a reagent strip, and the second type uses a reagent strip and a glucose meter.

Glucose also can be measured in the urine. Ketoacidosis is a complication of the inadequate treatment of diabetes. This condition can be identified by testing the urine for ketones.

Blood Glucose Reagent Strips: Reagent strips are saturated with glucose oxidase, an enzyme that interacts with glucose. When a drop of blood is placed on the strip, the glucose oxidase chemically reacts with the blood glucose and the resultant reaction produces a color change on the strip. The higher the glucose level, the greater the reaction and the more dramatic the color change. The blood glucose level can be determined by comparing the color of the strip with a color chart. For accurate results, test strips should be stored at room temperature and away from moisture. To protect the strips from moisture, bottles should be closed after use.

The disadvantage of reagent strips alone is that they do not give an exact glucose measurement. They are accurate enough, however, to alert patients to seriously high or low levels of glucose. Examples of reagent strips that are available over-the-counter (OTC) are Chemstrip bG and Glucostix. For an accurate blood glucose level, the reagent strip must be combined with a meters. (See below.)

Blood Glucose Meters: Self-monitoring of blood glucose is the most important tool a patient has to determine their level of glycemic control. This is simple to perform. It involves taking a small lancet, poking the finger (usually it's the tip of the finger, just off to the side, though now there are meters that allow for blood glucose testing to be performed at other sites, such as the forearm). Then a small quantity of blood is placed on a testing strip which is then inserted into a meter where the glucose value is read.

The meter reads the blood glucose level from the reagent strip. Results that are obtained using a glucose meter are more accurate than those obtained without the meter, that is, with reagent strips alone. However, the results using a meter are about 10-15% lower than the more accurate values determined in a clinical laboratory. Meters are accurate enough, however, for home monitoring and adjustment of insulin doses.

It is important to know that reagent strips are calibrated for specific meters. Most meters need to be calibrated once a new box of test strips is used. Inappropriate calibration will lead to errors in glucose readings. Using the wrong strip with a meter is also a source of error in glucose readings. Erroneous results can occur when:

• Meters are improperly calibrated;
• The meter is dirty;
• The battery in the meter is dead;
• Reagent strips are stored improperly;
• The reagent strips have expired;
• Not enough blood is applied to the reagent strip;
• Blood is not left on the reagent strip long enough or is left too long before reading;
• The test is performed under the wrong conditions of temperature and humidity; or
• Patients are dehydrated.

The main advantage of the self-monitoring of blood glucose is that it gives immediate feedback. Diabetics who are educated can make a decision in terms of insulin, diet, and exercise that immediately affects the glucose results. This, in turn, may give them more of a sense of control over their diabetes and may allow them to adapt the diabetes treatment plan to their life style rather than vice versa. Providing regular results to a physician allows for more frequent and accurate adjustments of the medication. This can result in improve symptoms and diabetic control more effectively, especially in an outpatient setting.

The main disadvantages of the self-monitoring of blood glucose are cost, discomfort, and inconvenience (such as having to interrupt one's usual activities to do it). In addition, some patients experience a feeling of frustration at seeing high blood glucose results when they expected lower readings. "The good thing about blood testing is that I know what my sugar is, and the bad thing about glucose testing is that I know what my sugar is."

The information obtained from self-monitoring of blood glucose is valuable to all patients with diabetes, even those controlled with diet and exercise, and those who required oral mediation. Many physicians routinely give all their patients with diabetes a glucose meter, along with an individualized schedule of when to test. This ranges from once a day up to 6 times a day, depending on what the patient needs. Introducing the self-monitoring of blood glucose in conjunction with diet education is very useful.

There are many meters available on the market to choose from that differ in attributes. They may vary in the amount of blood that is used, the speed at which results are displayed, the size of font of the displays, their ability to sore readings in memory, and down load capabilities. Newer meters function as a health PDAs, allowing the patients to enter other lab values, and dates and results of health visits. Newer meters may also store the strips right in the meter, thereby allowing the patient to avoid handling the strips. Examples of glucose meters available OTC are Accu-Chek III, Glucometer Elite XL, and One Touch Basic.

Urine Glucose Tests: The role for home urine glucose testing has faded with the easy use of fingerstick blood glucose monitoring. For those few patients who choose to do home urine glucose testing, they need to realize the limitations. It is only a rough estimate of blood glucose values. Also, it provides no information unless the kidney is spilling glucose, and that usually occurs at a blood glucose level of greater than 180mg/dl. Below that, the urine glucose values are negative.

Urine glucose levels should not be confused with checking microalbumin levels and protein levels. These test are performed in the doctor's office at least on an annual basis, and provide necessary information about kidney function, and provide the basis for obtaining information to see whether certain medications should be added.

Urine glucose tests also do not indicate the current blood glucose level but rather the glucose level during the period of time between the collection of the urine and the previous urination. In many patients, the level of blood glucose must be very high in order for glucose to appear in the urine. Therefore, the urine may be free of glucose, but blood levels of glucose still may be unacceptably high. Thus, results from urine glucose tests should not be used to adjust insulin doses.

There are two types of urine glucose tests. Both types rely on a chemical reaction that produces a color change. The tests use either tablets or strips. Generally, the test strip or tablet is placed in urine. The resulting color change is matched against a color chart provided by the manufacturer which shows the different colors produced by different levels of glucose.

The first type, called the copper reduction test, uses cupric sulfate (e.g., Clinitest). In the presence of glucose, cupric sulfate, which is blue, changes to cuprous oxide, which is green to orange. The reaction should be observed closely and the manufacturer's instructions closely followed. The copper reduction tests can react with substances other than glucose in the urine and lead to false positive results, meaning the test shows glucose when it is not present. Examples of these other substances include aspirin, penicillin, isoniazid, vitamin C, and cephalosporin-type antibiotics. Tablets and solutions utilizing copper reduction may damage the skin and are poisonous if ingested. They should be handled carefully and kept out of the reach of children.

The second type of urine glucose test, called the glucose oxidase test, uses the chemical toluidine and the enzyme glucose oxidase (e.g., Clinistix). Glucose oxidase converts the glucose in urine to gluconic acid and hydrogen peroxide. The interaction of the hydrogen peroxide with the toluidine causes a change in color. False negative results, meaning the test shows no glucose when glucose really is present, may occur in patients taking vitamin C, aspirin, iron supplements, levodopa, and tetracycline-type antibiotics. Glucose oxidase tests are more convenient to use and less expensive than copper reduction tests. The strips should be kept away from moisture.

Tests For Urinary Ketones: Ketone testing is an important part of monitoring in type 1 diabetes, and it is a tool that is often also used in pregnancies that are complicated by diabetes.

Ketones are formed when the body goes into starvation mode when there is a profound lack of insulin. When the body produces an insufficient amount of insulin, the cells are unable to remove glucose from the blood, and the level of glucose in the blood rises. The cells respond to what appears to be a lack of glucose by stimulating the body to produce larger amounts of glucose, and the blood glucose level rises further. In addition, ketones are produced by the cells. The presence of ketones signals a condition in diabetics called ketoacidosis. Ketoacidosis signifies that the cells are not getting enough glucose.

Severe diabetic ketoacidosis is a medical emergency since it can result in loss of consciousness and even death. There is a correlation between high blood glucose levels and ketones. The higher the glucose level, the more likely it is that there are ketones. Therefore, diabetics with blood glucose levels of 240 mg/dl or greater should test for urinary ketones. Patients with type 1 diabetes should test for ketones during acute illness and if they are in severe stress. Also, the urine ketones should be checked if any symptoms of ketoacidosis (nausea, vomiting, abdominal pain) are present.

Ketones can normally be found in the urine. For example, after an overnight fast, ketones can be seen in up to 30% of non-diabetic people. However, these levels of ketone production are usually below the threshold of measurement by the ketone test strips. The strips can also give false positive results when patients are on drugs such as captopril. False negative readings may be seen if the test strips are old, exposed to air, or if the urine is very acidic (such as after drinking a lot of orange juice, which is high in vitamin C).

Tests for ketones are based on the color change that occurs when ketones react with sodium nitroprusside or similar compounds. The tests are performed in a manner similar to that of urine glucose testing. There are different tests for the different types of ketones. For example, Acetest detects two ketones, acetoacetic acid and acetone, but does not detect another ketone, beta-hydroxybutyric acid. Ketostix detects only acetoacetic acid and, therefore, produces false negative results if only acetone and beta-hydroxybutyric acid are present in the urine. Ketone tests are supplied as strips or tablets.

The American Diabetes Association advises that ketone testing materials be available in the office setting and that physicians should prefer using blood ketone measurements over urine ketone measurements if possible. Home testing for blood ketones is also available, though not often used.

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Dr Marwah