Diabetes mellitus type insulin receptor

Disorders of lipoprotein metabolism involve perturbations which cause elevation of triglycerides and/or cholesterol, reduction of HDL-C, or alteration of properties of lipoproteins, such as their size or composition. These perturbations can be genetic (primary) or occur as a result of other diseases, conditions, or drugs (secondary). Some of the most important secondary disorders include hypothyroidism, diabetes mellitus, renal disease, and alcohol use. Hypothyroidism causes elevated LDL-C levels due primarily to downregulation of the LDL receptor. Insulin-resistance and type 2 diabetes mellitus result in impaired capacity to catabolize chylomicrons and VLDL, as well as excess hepatic triglyceride and VLDL production. Chronic kidney disease, including but not limited to end-stage... 

Another form of diabetes is non-insulin-dependent diabetes mellitus (NIDDM, or adult diabetes, or type II diabetes). In this case, insulin is produced and a normal insulin level is detected in blood. But for various reasons its effect is reduced. This may be caused by a reduced number of insulin receptors on cells, or reduced effectiveness in binding to these receptors. The cause is complex and may involve genetic make-up, changes in lifestyle, nutritional habits, and environmental factors. 

Acetazolamide is a carbonic anhydrase inhibitor that reduces aqueous humour production and is therefore indicated in glaucoma to reduce the intraocular pressure. Salbutamol is a selective, short-acting beta2-agonist used as a bronchodilator in asthma. Tolbutamide is a short-acting sulphonylurea used in type 2 (non-insulin dependent) diabetes mellitus. Chlorpromazine is an aliphatic neuroleptic antipsychotic drug used in schizophrenia. Zafirlukast is a leukotriene-receptor antagonist that is indicated in the prophylaxis of asthma but should not be used to relieve acute severe asthma. 

Oral antidiabetic agents might be indicated in noninsulin dependent diabetes mellitus (NIDDM), i.e. diabetes Type II where insulin resistance caused by down-regulation of insulin receptors or a failure of the pancreas to release insulin even though it is formed, play a role. However, oral antidiabetic... 

Examples of some conditions which are known,or are believed to be, to be autoimmune responses include myasthenia gravis (destruction of acetylcholine receptors), rheumatic fever (a streptococcal infection challenges the immune system and then the immune system mistakes heart tissue for another strep infection), Addison s disease (destruction of the adrenal glands), arthritis (an infection of unknown origin starts the immune response but somehow IgG becomes changed, enough so as to start another IgM response - this time to the body s own IgG), pernicious anemia (inability to process vitamin B12)- insulin-dependent diabetes mellitus (IDDM or type I diabetes), multiple sclerosis, aspermatogenesis, and photosensitivity. 

Glucophage is an antidiabetic drug prescribed to treat Type II diabetes. Type II diabetes is also called non-insulin-dependent diabetes mellitus. Individuals who have Type II diabetes are usually unable to produce enough insulin naturally (in response to the food they ingest) or suffer cell insulin receptor-site insensitivity. However, Glucophage can be prescribed by a doctor for Type I diabetics as a means of additional glucose (blood sugar) control in unison with insulin injections. 

It appears that insulin and certain growth factors may exert their effects by acting through this type of tyrosine kinase receptor-enzyme system.21,44 Insulin, for example, binds to the extracellular component of a protein located on skeletal muscle cells, thereby initiating activation of this protein s enzymatic activity on the inner surface of the cell membrane. This change in enzyme function causes further changes in cell activity, which ultimately result in increased glucose uptake in the muscle cell. The function of insulin receptors and their role in the cause and treatment of diabetes mellitus are discussed in more detail in Chapter 32. 

Leptin therapy has corrected obesity in a child with congenital leptin deficiency. In obese individuals, the presence of circulating high levels of leptin has been attributed to resistance or some other defect in the leptin receptors. This apparent paradox of high leptin levels associated with obesity is analogous to insulin resistance seen in type 2 diabetes mellitus. In general, in the vast majority of obese patients, the molecular defects remain unknown. Diet and exercise are the mainstays in the management of obesity. 

In type II (adult onset, non-insulin-dependent diabetes mellitus NIDDM]), the problem lies at the level of the receptor rather than the islet cell. Typically, these patients produce insulin, but the receptors are either desensitized or are associated with a defective transduction mechanism. 

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