The 3 classic symptoms of diabetes mellitus are polyuria, polydipsia and polyphagia -- also known as the 3 P's. Polyuria, polydipsia and polyphagia are defined as an increase in urination, thirst and hunger, respectively. The presence of the 3 P's is a good indication that your blood sugar may be too high. With type 1 diabetes (T1DM), these symptoms typically develop relatively quickly and are more obvious, often leading to diagnosis of the condition. With type 2 diabetes (T2DM), the 3 P's are often more subtle and develop more gradually. As a result, people with type 2 diabetes may overlook these symptoms, leading to a delay in diagnosis.
Classic Symptoms of Diabetes
The 3 P's of diabetes are typically among the first symptoms to occur in T1DM, but they can occur with other conditions. Polyuria, or excessive urine production, can be identified by needing to urinate during the night, frequent bathroom trips or accidents in potty-trained children. Polydipsia, a consequence of polyuria, is characterized by excessive thirst. An increase in fluid intake due to polydipsia can also contribute to increased urination.
Polyphagia is the term for excessive or increased hunger. It occurs with diabetes because blood sugar is fails to enter body tissues normally, leaving them short of fuel to produce energy. To compensate, fat and muscle are broken down and used for energy resulting in weight loss, lack of energy and fatigue, which are most often seen with T1DM. Signs of long-term high blood sugar, such as blurred vision and tingling or numbness in hands and feet, are more common at diagnosis with T2DM.
High Blood Sugar and the 3 P's
The 3 P's of diabetes all stem from high blood sugar levels. Blood sugar is normally filtered by the kidneys but then reabsorbed into the blood. When blood sugar levels are high, the kidneys cannot reabsorb all of the sugar, and it ends up in the urine. When there is sugar in the urine, excess body water is lost in the urine and so polyuria develops. This loss of body water contributes to dehydration and increased thirst, or polydipsia. Polyphagia develops when lack of insulin or a reduced response to it leads to poor absorption of blood sugar into the body tissues. Lack of sugar within body cells leads to reduced energy production. Increased hunger, or polyphagia, results.
Occurrence of the 3 P's
The 3 P's occur more frequently in T1DM than T2DM. The medical text "Evidence-Based Diabetes Care" states that 93 percent of children and adolescents have polyuria at the time of diagnosis. Polydipsia occurs in 93 to 97 percent and weight loss in 52 to 72 percent. T1DM is caused by the destruction of insulin-producing cells in the pancreas. The insulin deficiency typically leads to obvious symptoms when a critical number of insulin-producing cells have been lost. In contrast, T2DM occurs when the body gradually becomes resistant to the effects of insulin. Because T2DM develops gradually, symptoms are usually less obvious than with T1DM and may go unrecognized. People with T2DM may have minimal symptoms for years before being diagnosed.
Warning Signs and Complications
If you experience any symptoms of diabetes, call your doctor right away. Untreated high blood sugar sometimes leads to potentially life-threatening metabolic crises, including diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). These conditions can be the presenting manifestations of undiagnosed diabetes and can cause coma or death, so emergency medical attention is needed. In addition to the 3 P's, symptoms of DKA include: -- A fruity odor on the breath. -- Nausea, vomiting and abdominal pain. -- Dry mouth and dizziness.
DKA occurs more frequently in T1DM but can also occur with T2DM. Approximately 20 percent of adults and 30 to 40 percent of children have DKA at the time of their T1DM diagnosis, according to a January 2002 article in "Diabetes Spectrum." The authors also report that HHS is present in 7 to 17 percent of people when T2DM is initially diagnosed. Symptoms of HHS -- which is more common with T2DM than T1DM -- include: -- Extremely high blood sugar. -- Polydipsia. -- Confusion or poor concentration.. -- Fever.
Is This an Emergency?
- Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 4th Edition; Carl Burtis et al.
- Robbins and Cotran Pathologic Basis of Disease, 9th Edition; Vinay Kumar et al.
- Diabetes Care: Classification and Diagnosis of Diabetes
- Diabetes Spectrum: Diabetic Ketoacidosis and Hyperglycemic Hyperosmolar Syndrome
- Evidence-Based Diabetes Care; Hertzel Gerstein and R. Brian Haynes