Diabetes results from inadequate levels of insulin. Type I diabetes is characterized by inadequate levels of insulin secretion, often due to a genetic cause. Type II usually develops in adults from both genetic and environmental causes. Loss of response of targets to insulin rather than lack of insulin causes this type of diabetes. Diabetes causes impairment in the functioning of the eyes, circulatory system, nervous system, and failure of the kidneys. Diabetes is the second leading cause of blindness in the US. Treatments involve daily injections of insulin, monitoring of blood glucose levels and a controlled diet.
Steroid hormones are synthesized from cholesterol in the gonads and adrenal glands. A quick glance at their structures ( Figs. – ) shows how closely they resemble cholesterol (and one another) and therefore are lipids that are at home in membranes. They can readily move about laterally, undergo flip-flop and can pass through membranes until they encounter their appropriate steroid hormone receptor in the cytosol or nucleus [41,43] . In the cytosol, the steroid hormone may or may not be further enzymatically modified and can then bind to its receptor. The steroid hormone–receptor complex can immediately alter intracellular metabolic events by rapid, nongenomic mechanisms  . Alternatively, some steroid hormones bind to nuclear receptors  . The nuclear steroid hormone–receptor complex then binds to specific DNA sequences, inducing transcription of its target genes. This instigates slow-acting genomic responses. In either case, the hormone–receptor complexes cause changes in the target cell's basic physiology. With limited water-solubility, steroid hormones must be transported through the blood bound to specific carrier proteins.