Diabetic Hyperglycemia

In diabetes, the uptake of glucose in muscle and fat decreases due to a loss of insulin production or to a lack of an adequate response to the hormone. This results in increases in the blood level of glucose. When the concentration of glucose exceeds 8-10 mmol/l, it is lost to the urine. This is due to the inability of the kidneys to reabsorb all of the glucose present in the first filtration product in the kidney (pre-urine) when the glucose concentration exceeds around 10 mmol/l. Diuresis (loss of water due to the osmotic effect of glucose) follows with loss of electrolytes, mainly sodium and potassium. In diabetes type 1 (characterized by destruction of ?-cells), the daily carbohydrate loss can be the equivalent of 2 loaves of bread. Children who develop this disease become extremely thirsty, have to urinate frequently and lose weight rapidly.
Hormones that balance insulin s action and that increase blood glucose levels come into play when blood glucose falls to around 3.8 mmol/l. We see that secretion of glucagon, adrenaline and growth hormone are stimulated by falling blood glucose levels. It is important to recognize that there is a constant basal secretion of insulin and glucagon and that it is the molar ratio of these two hormones that directs metabolism. This is like driving a car with one foot on the gas and the other on the brakes. You get a very exact control over the car, but you loose some energy too. Our bodies are designed to obtain maximal control over metabolism, allowing some energy waste that, at the same time, keep us warm.