Overview



Overview

Diabetes Mellitus

A condition where the body does not produce enough insulin or it does not respond to insulin.

Types:

Diabetes Mellitus I – failure to produce insulin

Diabetes Mellitus II – Insulin resistance

Insulin – hormone released at a basal rate by the beta cells of the islets of langerhans. It circulates in plasma and acts by binding to insulin receptors present on most cells of the body. Once bound, it works through a protein kinase messenger system to cause an increase in the number of glucose-transporter molecules present in the outside of the cell membrane. Glucose-transporter molecules (Glut-4 glucose transporter) facilitates diffusion of glucose across the cell membrane.

Feedback Cycle on Increased Blood Glucose

Stimulus:

Increased blood glucose

Pancreas:

Insulin release

Insulin stimulates glucose transport

Glucose diffused to most of the body cells

Decreased blood glucose

(normoglycemia)

Feedback Cycle on Decreased Blood Glucose

Stimulus:

Decreased blood glucose

Counter regulatory hormone primarily glucagon and epinephrine

Stimulates glucose release from liver and inhibit insulin secretion

Increased blood glucose

(normoglycemia)

Diagnostic Tests

Blood Glucose Test

Indications

1. Routine screening for Diabetes Mellitus

2. Clinical symptoms of hypoglycemia or hyperglycemia manifest

3. Monitoring of response to therapy for abnormal glucose metabolism

4. Monitoring response to drugs known to alter blood glucose levels

Fasting Blood Sugar

The blood glucose level is usually maintained in a range of 80-120mg/dl. Between meals, and even during an overnight fast, that level is still maintained, even in the absence of food intake. The body does this by converting glycogen to glucose and, when necessary, fats to glucose. These two methods of producing glucose maintain a normal glucose level during fasting.

The ability to convert glycogen to glucose presupposes that the body converts glucose to glycogen when the glucose level is high, that is, after a meal. This process, which requires insulin, brings the glucose level back to normal a few hours after a meal.

In a diabetic, the lack of insulin keeps the glucose level elevated even after fasting overnight. When the blood sugar level reaches a critical level, symptoms of osmotic diuresis will be felt.

If fasting sample is to be drawn, food and insulin or any oral hypoglycemic agent should be withheld for approximately eight (8) hours prior to test. (Usually client takes only water at midnight)

Procedure:

Blood sample obtained through venipuncture

Nursing care post procedure

Resume food and medications after test

Abnormal Values

1. Assess for symptoms associated with hyperglycemia (polyuria, possible dehydration, polydipsia, or weight loss)

2. Prepare for additional glucose test for Diabetes Mellitus client

3. Monitor I&O

4. Prepare to administer ordered medications (insulin or oral hypoglycemic)

5. Assess for signs and symptoms of hypoglycemia (weakness, sweating, nervousness, hunger, confusion, or palpitations)

6. Prepare to administer sucrose or glucose orally or IV

7. Instruct client to keep readily-absorbed carbohydrates on hand.

Critical Values

Infants

300mg/dl

Adult

700mg/dl

Two-Hour Postprandial Blood Glucose (Postprandial Blood Sugar)

It reflects the metabolic response of the body to carbohydrate challenges. It may also be used to check for Diabetes and to see how treatment for diabetes is working.

Normally, before age 50, blood sugar levels should rise not higher than 140 mg/dl 2 hours after meals. Healthy adults increase blood sugar levels by 10 mg/dl for every 10 years of life after 50 years old.

Indications:

1. Abnormal fasting blood sugar

2. Known or suspected disorder associated with abnormal glucose metabolism

3. Monitoring response to drugs known to alter blood glucose levels

Diet: 100g of carbohydrate in the diet

Interfering Factors:

1. Failed to follow dietary instructions

2. Smoking and drinking coffee during the 2-hour test period may lead to falsely elevated values

3. Strenuous exercise during the 2-hour test period may lead to falsely decreased value.

Nursing care before procedure

1. Ingesting a meal (usually breakfast) containing at least 100g. of CHO 2-hours pretest.

2. Note time of last meal before test

3. After meal, client should fast and avoid coffee, smoking, and strenuous exercise.

Complications and Precautions:

Abnormal increased or decreased values are treated in the same way as for blood glucose testing. If glucose level does not return to a fasting state in 3 hours, an additional glucose tolerance test is required.

Oral Glucose Tolerance Test

Used for individuals who are able to eat and who are not known to have GI malabsorption. The client should be in a normal nutritional state and should be in a normal physical condition. (CHO depletion and inactivity may impair glucose tolerance)

Indications:

1. abnormal FBS or PPBS results not indicative of DM

2. Modest elevation of blood glucose 2 hours and a normal level after 3 hours

3. Support for diagnosing hyperthyroidism and alcoholic liver disease.

Interfering Factors:

1. Failure to ingest sufficient CHO for at least 3 days. May result in falsely decreased values.

2. Impaired physical activity may lead to falsely increased values

3. Excessive physical activity and smoking may lead erroneous values.

Nursing care:

1. Diet (at least 150g. of CHO for 3 days); provide menus or lists of food

2. Tell client which meds should be withheld

3. Tell client that no food may be eaten midnight before the test but water is not restricted.

4. Tell client the importance of not smoking or not doing strenuous exercises.

5. Report s/sx of hypoglycemia

Procedure:

1. Venipuncture from FBS

2. Second-voided urine is tested for glucose (void 30 minutes prior to test and discard then collect urine at the time of the test)

3. Glucose load is administered PO (calculated dose usually 1.75 g/kg body weight or 50 g/sq. m. body surface)

4. Blood and urine sample are obtained with ½ hour, 1 hour, 2 hours and 3 hours intervals. (second voided urine is necessary only at the beginning)

5. Client should drink one glass of water per urine collection to ensure adequate urine specimen.

Glycosylated Hgb

The level of glycosylated Hgb reflects the average blood sugar over a period of several weeks.

Hgb molecules incorporate glucose into its beta chain.

The test is used to evaluate the overall adequacy of diabetic control and provides information that may be missed by individual blood and urine glucose test. This test is more convenient because it is done only every 5 to 6 weeks and because there is no dietary or medication restrictions before test.

Indications:

1. Monitoring adequacy of insulin dosage for blood glucose control, i.e. that administered by automatic insulin pumps

2. Evaluates the diabetic client’s degree of compliance with the prescribed therapeutic regimen.

Interfering factors

1. Individuals with hemolytic anemia and increased levels of young RBC may have spuriously low levels.

2. Individuals with increased Hgb levels or on heparin therapy may have falsely increased levels.

Nursing care;

1. Inform client that diet and medications will not alter results

Complications and precautions

a value of >15% of total Hgb A1c indicates diabetes out of control. Notify the physician at once.

Reference Values:

Hgb A1c = 3-6% Hgb

Hgb A1c = 7-11% in diabetes under control

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