Medical Surgical Lecture Notes for Diabetes Mellitus: Definition, Diagnosis, Pathophysiology, Management, Treatment
Diabetes Mellitus (DM) is a chronic systemic disease affecting people of all ages. It basically has three types: Type I (IDDM), Type II (NIDDM), and GDM or Gestational Diabetes which is associated with pregnancies. It is characterized by lack of or decreased ability of the body to use insulin.
- -Insulin dependent Diabetes Mellitus (Juvenile-onset Diabetes)
- -Condition marked by absolute insulin deficiency secondary to the destruction of pancreatic beta cells. (remember: beta cells of the pancreas produce insulin)
- - Non-insulin dependent Diabetes Mellitus (Adult-onset Diabetes)
- -Impaired tissue sensitivity to insulin or impaired insulin secretion
- Diagnosis of Diabetes mellitus that applies to women in whom glucose intolerance develops during pregnancy (usually after 24 weeks AOG).
II. HISTORICAL BACKGROUND
In late nineteenth century, when diabetes was already a well-known abnormality in carbohydrate metabolism, scientists thru experiments that removal of the islets of langerhans in the pancreas produces DM in animals. Later on this knowledge paved way to the discovery of naturally produced insulin in 1921. Insulin was then injected to diabetic patients hence the first and proven treatment of Diabetes mellitus. Before injectible insulins were developed, diabetic patients die in a year of two after the onset of Diabetes mellitus, and even a few weeks after suffering from its symptoms.
Dr. Elliott Joslin of Boston was noted as an early pioneer in the quest for finding cure to this dramatically-brutal disease. He asserted that diabetic patients need to gain full knowledge of the disease so he could better take care of himself. A well-knowledgeable physician may not be enough, since the diabetic patient and his family play a vital role in the management of Diabetes Mellitus.
III. RISK FACTORS/PREDISPOSING FACTORS
Type 1 Diabetes mellitus
-IDDM or juvenile-onset Diabetes mellitus is inherited as a heterogenous, multigenic trait. 10% of diabetic patients suffer from type 1 DM which is usually diagnosed before the age of 30. Identical twins have a risk of 25% to 50% of inheriting this disease, whereas siblings have a 6% risk, and offspring a 5% risk. There is also an ssociation between type 1 diabetes and HLAs (Human Leukocyte Antigens).
Type 2 Diabetes mellitus
-previously called NIDDM (non-insulin dependent Diabetes mellitus), involves both genetic and environmental factors. It is not associated with HLAs and circulating ICAs are rare. It is more common in identical twins, with a risk factor of 58% to 75% than in general population. Obesity is also a major risk factor as such that 80 to 85% of diabetic patients are obese.
IV. PATHOPHYSIOLOGY (DIAGRAM)
V. CLINICAL MANIFESTATIONS (SIGNS AND SYMPTOMS)
Clinical manifestations of Diabetes mellitus is tagged as 3 P’s : Polydipsia, Polyuria, Polyphagia. Some references would use 5 P’s, with the addition of Pruritus and Paresthesia.
Polyuria is frequent urination because the water is not being reabsorbed by the body by the renal tubules. This eventually leads to dehydration, hence diabetic patients also feel excessively thirsty, a condition known as polydipsia. Increased catabolic activity of the body makes a diabetic person hungry, this is termed as polyphagia. Pruritus is a condition of the skin that is extremely uncomfortable at times and may be relieved by emollient baths.
Laboratory tests are needed in order to establish a diagnosis of Diabetes.
a. Fasting blood Sugar/ Fasting Blood glucose
-A blood sample is taken from a patient who has taken nothing by mouth (NPO) for at least 8 hours. If the patient’s blood glucose level is 110 to 126 mg/dl, this would indicate an IFG or Impaired fasting Glucose. A diagnosis of DM is made if the patient’s blood glucose is greater than 126mg/dl.
b. Casual Blood Glucose
-A blood sample is taken from patient without a need for fasting. This is also called random blood sugar test. A blood glucose level of greater than 200 mg/dl is suggestive of diabetes. Elevation of blood glucose occur when patient is under stress, after a meal, from samples drawn from an IV site, and in diabetic patients.
c. Postload Blood glucose
-Also known as postprandial glucose test, is done two hours after a patient has taken his standard meal. Normally, blood glucose would return to fasting level within two hours. If after two hours the glucose level remains elevated at a level greater than 200 mg/dl during an OGTT, a diagnosis of Diabetes mellitus is made.
d. Glycosylated hemoglobin
-Glucose attaches to the haemoglobin molecule of an RBC (Red blood cell) and does not tend to disassociate. The higher the blood glucose level would mean higher levels of glycosylated haemoglobin (HbA1c). A1c is an average blood glucose level measured over the previous 3 months.
e. Oral Glucose Tolerance test
-usually not recommended in hospitalized clients because results are easily altered by many external and internal factors.
f. Self-Monitoring of Blood Glucose
-Provides an immediate feedback and data on blood glucose levels. SMBG is recommended for all clients with diabetes, regardless of the type of diabetes that they have. It is also a way on gaining knowledge on how a diabetic patient respond to food, insulin, exercise and stress.
When and how many times in a day an SMBG is done vary from patient to patient. It largely depends on patient needs and goals. However, it is recommended that type 1 and GDM patients taking insulin take SMBG three or more times daily. SMBG is done prior to taking a meal, before bedtime, and in the middle of the night. For type 2 DM patients, an agreement is set between the client and his health care provider. If they are taking oral medications, SMBG are usually done less frequently.
There are also some instances that a diabetic patient need SMBGs such as when feeling ill, or if experiencing hypoglycaemia ( pallor, diaphoresis or excessive sweating, cold clammy skin, faintness, weakness). It is also a standard procedure to do SMBG if patient frequently suffer from insulin reactions overnight.
1. Oral Antidiabetes Agents
a. Sulfonylureas (an oral hypoglycaemic agent)
b. Meglitinides (OHA)
c. Biguanides (insulin sensitizers)
d. Thiazolidinediones (insulin sensitizers)
e. Alpha-glucosidase inhibitors
2 to 4 hours duration with peak onset of 1 hour. Examples are humalog and Novolog
4 to 6 hours duration; 2-4 hours peak time. Examples include Humulin R and Novolin R
Cloudy appearance; 10-16hours duration and peaks at 4-10 hours. Examples are Humulin N (NPH), Humulin L (Lente), Humulin 70/30 (Premixed)
18-24 hours duration depending on type. Examples are Humulin U(Ultralente) and lantus (insulin glargine)
3. Exercise and Proper Diet
VIII. Injection of Insulin Dose
1. Wipe site of injection with cotton swab dipped with alcohol
2. With one hand, pinch up skin at injection site and quickly insert needle for its entire length in order to ensure injection of sufficient depth. The more rapidly the needle is inserted, the less pain will be felt.
3. Inject insulin dose. Make sure insulin temperature is at room temperature. Do not massage site of injection.
4. Rotate site of injection for best absorption of insulin.
IX. Insulin Pump Therapy
A small portable pumps for continuous administration of regular insulin are now used by diabetic patients. In this method, a small pump is worn externally and automatically injects insulin subcutaneously into the abdominal area through an indwelling needle site (changed daily).
How does it works? Insulin is infused to the patient at a low basal rate that matches a client’s basal metabolic needs. Boluses are infused before meals.
Advantage of the insulin pump includes a continuous infusion of insulin. However, it is recommended that the patient undertake SMBG (self-monitoring blood glucose) at least four times daily.