m INSULIN-DEPENDENT DIABETES MELLITUS.
The primary cause of insulin-dependent diabetes mellitus (IDDM), or Type 1 diabetes, is inadequate insulin production by the beta cells of the pancreatic islets. In most cells, glucose trans port cannot occur in the absence of insulin. When insulin con- -centrations decline, cells can no longer absorb glucose; tissues remain glucose starved, despite the presence of adequate or even excessive amounts of glucose in the bloodstream.
After a meal rich in glucose, blood glucose concentrations may be come so elevated that the kidney cells cannot reclaim all the glucose molecules that enter the urine. The high urinary concentration of glu cose limits the ability of the kidneys to conserve water, so the individ ual urinates frequently and may become dehydrated. The chronic dehydration leads to disturbances of neural function (blurred vision, < tingling sensations, disorientation, and fatigue) and muscle weakness.
Despite high blood concentrations, glucose cannot enter en docrine tissues, and the endocrine system responds as if glucose were in short supply. Alpha cells release glucagon, and glucocor-ticoid production accelerates. Peripheral tissues then break down lipids and proteins to obtain the energy needed to continue func tioning. The breakdown of large numbers of fatty acids promotes the generation of molecules called ketone bodies. These small ; molecules are metabolic acids whose accumulation in large num bers can cause a dangerous reduction in blood pH. This condi- , tion, called ketoacidosis, commonly triggers vomiting. In severe cases, it can progress to coma and death.
If the individual survives (an impossibility without insulin ther apy), long-term treatment involves a combination of dietary control, monitoring of blood glucose levels several times a day, and the ad- , ministration of insulin, either by injection or by infusion, using an insulin pump.