The 3 P’s of of Diabetes Mellitus are polyuria, polydipsia and polyphagia. Explain what each sign is and the reasons why each occurs from a biological perspective. Be sure to explain if each sign relates to Type 1, Type 2 diabetes or both.
The Correct Answer and Explanation is:
The 3 P’s of Diabetes Mellitus are polyuria, polydipsia, and polyphagia, which are hallmark signs that often indicate the presence of diabetes. These symptoms can occur in both Type 1 and Type 2 diabetes, though the underlying processes may vary slightly depending on the type. Below is an explanation of each sign and the biological reasons behind them:
1. Polyuria (Excessive Urination)
Polyuria occurs when there is an abnormally large production of urine. In diabetes, blood glucose levels become elevated due to a lack of insulin (Type 1) or insulin resistance (Type 2). Once blood glucose exceeds the renal threshold (approximately 180 mg/dL), the kidneys cannot reabsorb all the filtered glucose. The excess glucose stays in the filtrate, drawing water along with it by osmosis. This leads to increased urine production.
2. Polydipsia (Excessive Thirst)
Polydipsia is excessive thirst, often a direct response to polyuria. As the body loses significant amounts of water through frequent urination, dehydration occurs. The body signals the hypothalamus to trigger thirst, prompting the individual to drink more fluids to compensate for fluid loss.
3. Polyphagia (Excessive Hunger)
Polyphagia is excessive hunger that results from the body’s inability to properly use glucose for energy. In Type 1 diabetes, insulin production is absent, so glucose cannot enter the cells. In Type 2 diabetes, insulin resistance prevents glucose uptake. Despite high levels of glucose in the blood, the cells are starved for energy, causing increased hunger as the body attempts to obtain energy from food.
Occurrence in Both Types
These three symptoms are present in both Type 1 and Type 2 diabetes. However, they tend to appear more suddenly and severely in Type 1 diabetes, often leading to earlier diagnosis. In Type 2 diabetes, these symptoms may develop gradually as insulin resistance progresses.
