Diabetics may be unaware that they have the disease until there are obvious signs or symptoms. Diabetes mellitus (DM) is caused by destruction of the pancreas (type 1 DM) or insulin resistance in tissues (type 2 DM). Gradual decline in normal glucose metabolism slowly increases blood glucose levels. The body compensates until it can no longer do so. Gradually, patients experience symptoms associated with high glucose levels. Although there is no one presentation of diabetes, there are three classic symptoms associated with its diagnosis. The memory tool used to remember the tell-tale triad is referred to as the 3 P's of Diabetes.
Polydipsia (Increased Thirst)
Diabetes is a disease of abnormally high levels of glucose in the blood. It is the body's response to this extreme that leads to polydipsia. The body is always seeking to maintain balance. When there are abnormally high levels of glucose in the blood, fluid leaves tissues and enters vessels in an effort to balance water and glucose. This is is called osmosis. Performing this task is done at a deficit to other important tissues like muscle and fat. Dehydration in tissues signals the special part of the brain called the thirst center. The thirst center tells the patient that they need more water, resulting in increased intake. Patients may feel like they can not quite quench their thirst.
Polyuria (Increased Urine Output)
Polyuria is an abnormally high volume of urine production. Patients with diabetes often present with this classic symptom. As before mentioned, glucose is an osmolyte. The laws of chemistry dictate that where there are more osmotic molecules water must follow. Uncontrolled diabetes means an excess of glucose, leading to tissue dehydration. It causes a condition called osmotic diuresis. In other words, increased urination. Increased urine output is a partial explanation for osmotic diuresis. Increased oral intake adds to the reason why there is an increase in urine. Increased input equals increased output.
Polyphagia (Increased Intake)
Extreme hunger is often seen in patients presenting with diabetes. New diabetics or uncontrolled known diabetics usually report that they can't seem to get enough to eat. This is because their muscles are not getting the fuel that enters the body. It is as if the patient never ate. In diabetes, glucose may be in abundance in the blood but, it needs insulin to enter into cells. Impaired insulin inhibits the use of glucose by cells. In response, hungry muscles signal a demand for more energy. The brain translates this as an increase in appetite. Patients may not feel satisfied after a meal.
