Metabolic Disturbances and Complications of the Diabetic State

 METABOLIC DISTURBANCES AND COMPLICATIONS OF THE DIABETIC STATE

 

There are only two major sources of blood glucose: ex-ogenous, or the ingestion of dietary carbohydrate, and endogenous, which is contributed by hepatic and renal gluconeogenesis and hepatic glycogenolysis. Diabetes mellitus is a metabolic disorder in which carbohydrate metabolism is reduced while that of proteins and lipids is increased. In diabetics, exogenous and endogenous glu-cose is not used effectively, and it accumulates in the blood (hyperglycemia). As blood glucose levels in-crease, the amount of glucose filtered by the glomeruli eventually exceeds the reabsorption capacity (Tm, trans-port maximum) of the proximal tubule cells, and glu-cose appears in the urine (glucosuria). Protein catabo-lism and the rate of nitrogen excretion are increased when blood insulin falls to low levels; stimulation of he-patic gluconeogenesis converts amino acids to glucose. The catabolism of lipids and fatty acids is also acceler-ated in the absence of insulin, leading to the formation of ketone bodies, such as acetoacetic acid, -hydroxybu-tyric acid, and acetone. Renal losses of glucose, nitroge-nous substances, and ketone bodies promote osmotic diuresis that can result in dehydration, electrolyte ab-normalities, and acid–base disturbances. Diabetic ke-toacidosis is the end result of insulin deficiency in un-controlled type I diabetes.

 

Type II diabetics are less prone to develop ketone bodies or diabetic ketoacidosis but may develop hyper-osmolar coma, a condition characterized by severe hy-perglycemia and dehydration. Both diabetic ketoacido-sis and hyperosmolar coma are medical emergencies that require prompt insulin administration and intra-venous fluids.

 

Diabetes mellitus is associated with many complica-tions that are increased in the setting of poor glycemic control. Diabetes mellitus can cause microvascular complications (e.g., retinopathy, nephropathy, and neu-ropathy) and macrovascular complications (e.g., athero-sclerotic cardiovascular disease), associated with dia-betic dyslipidemia (usually elevated triglycerides and low-density lipoprotein cholesterol). Recent clinical tri-als have demonstrated that the risk of developing chronic complications of diabetes is reduced by achiev-ing good glycemic control. This can be accomplished by a combination of diet, exercise, and rational pharmaco-logical therapy directly targeted to optimize diabetes management.

Comments

Post a Comment

Popular posts from this blog

Parathyroid Hormone

  PARATHYROID HORMONE   PTH is secreted from the parathyroid glands in response to a low plasma concentration of ionized (free) calcium. PTH immediately causes the transfer of labile calcium stores from bone into the bloodstream. PTH increases rates of dietary calcium absorption by the intestine indi-rectly via the vitamin D 3  system activation of enterocyte activity. Within the kidney, PTH directly stimulates cal-cium reabsorption and a phosphate diuresis.     Chemistry   PTH is a single-chain polypeptide composed of 84 amino acid residues that is devoid of disulfide bonds and has a molecular weight of 9500. Biological activity of the human hormone resides primarily in the amino terminal end of the protein (i.e., amino acids 1–34). This portion of PTH has full biological activity both in vivo and in vitro. Synthetic fragments of the 1-34 portion of the PTH molecule have been synthesized. A paraneo-plastic hormone,  PTH related peptide  ( PTHrP )...
Read more

Vitamin Toxicity

  VITAMIN TOXICITY     Toxic effects have been observed when large dosages of some vitamins are ingested. Generally the water-soluble vitamins are less toxic, since excess quantities are usu-ally excreted in the urine. Excessive amounts of fat-soluble vitamins, however, are stored in the body, which makes toxic levels of these vitamins easier to obtain.
Read more

Androgens: Adverse Effects

  ADVERSE EFFECTS   As a class, the androgens are relatively safe and non-toxic. However, in inappropriate doses or for inappro-priate reasons, their use can result in significant toxicity.   Toxicity in Men   The administration of androgens to sexually mature hy-pogonadal men is associated with few untoward effects. However, prepuberal or hypogonadal males never ex-posed to testosterone show enhanced sensitivity to ad-ministered androgens, and many do not like the effects. Testosterone administration can cause irritability, agita-tion, or aggressive behavior. Androgen administration to normal males inhibits the release of the pituitary go-nadotropins FSH, LH, and as a consequence, endoge-nous testicular production of testosterone is reduced. Spermatogenesis is also reduced, and if administration is continued, azoospermia and infertility may result. Peripheral aromatization of androgens to estrogens can cause gynecomastia. Cessation of exogenous androgen treatment in...
Read more