Polyuria, Polydipsia and Polyphagia - Three Signs of Diabetes

Polyuria, Polydipsia and Polyphagia

We know that excess glucose in the blood that doesn't go away without some help is diabetes. This is how the three signs above are created in diabetes.

The excess glucose in the urine filtrate acts as an osmotic diuretic. Wow! big words again for us to master. 

First, a simple definition of osmosis that will never get you into trouble, well seldom, never is an impossible situation.

Osmosis is the movement of water through a selective permeable membrane (think cell membrane if you have a tiny mind like me!)from an area of low solute concentration (anything dissolved in water (the solvent) into a area of high solute concentration.

In this illustration, due to the large amount of excess glucose in the filtrate, (what the kidney filters from the blood under pressure) the glucose is the "solute molecule" and causes the concentration of solutes in the kidney filtrate to be higher than the solute concentration in the blood. Net result, instead of water being returned to the blood it is flushed out of the body in the urine! Thats called diuresis.

A diuretic, in this case, is something that inhibits water reabsorption by the blood from the kidney tubules that results in a hugh urine output that is called Polyuria.

The polyuria results in decreased blood volume and dehydration. Thats why a diabetic person experiences excessive thirst. Lets look at how that "thirst" occurs technically.

Along with water loss, which is a solvent, serious electrolytelosses also occur as the body rids itself of excess ketones.

The ketone bodies are negatively charged particles called ions. Keep in mind a balance is maintained between positive and negative ions in the body. But, in mass movements involving negative charged ketone bodies, they attract and carry positve charged ions like sodium (Na+) and potassium (K+)out of the body fluids as well. 

This creates an electrolyte imbalance in you, if you are a diabetic out of control. Because of this imbalance you get abdominal pains and may vomit, and the stress reaction  ("flight, fright and frolic") about diabetes mellitus just accelerates even more.

Vomiting expels even more water from the body and carries with it more important electrolytes. This rapid water loss, or dehydration, stimulates the hypothalmic thirst centers causing polydipsia or excerssive thirst.

If the general body cells cannot take up glucose for metabolism to take place you develop excessive hunger pangs and increase your food consumption accordingly. This is called polyphagia. You sense, correctly, that you are starving to death. Although you have plenty of glucose available, it cannot be used, and the body begins to use the fat and protein stores for metabolism.

If you are a Type I Diabetic you can develop long term vascular and neural problems. The lipidemia and high blood cholesterol levels, characteristic of the disease, can lead to severe vascular complications like atherosclerosis, strokes, heart attacks, renal shutdown, gangrene and blindness.

Neural changes include loss of sensation, impaired bladder function and impotence.

Hope this helps with your understanding of the course that diabetes follows in a Type I diabetic.