Diabetes mellitus is classified as type 1 (T1DM) and type 2 (T2DM). T1DM is characterized by destruction of pancreatic beta cells, and exogenous insulin is required for treatment. T2DM can be due to numerous factors but is usually characterized as insulin resistance coupled to some degree of beta cell deficiency. Patients with T2DM may require exogenous insulin at some point to maintain blood glucose levels.
19. Obesity-associated T2DM is currently at epidemic proportions worldwide and is characterized by insulin resistance due to lipotoxicity, hyperinsulinemia, and inflammatory cytokines produced by adipose tissue. T2DM is often associated with obesity, insulin resistance, hypertension, and coronary artery disease. This constellation of risk factors is referred to as the metabolic syndrome.
20. Major symptoms of diabetes mellitus include hyperglycemia, polyuria, polydipsia, polyphagia, muscle wasting, electrolyte depletion, and ketoacidosis (in T1DM).
21. The long-term complications of poorly controlled diabetes are due to excess intracellular glucose (glucotoxicity), especially in the retina, kidney, and peripheral nerves. This leads to retinopathy, nephropathy, and neuropathy.
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22. Adipose tissue has an endocrine function, especially in terms of energy homeostasis. Hormones produced by adipose tissue include leptin and adiponectin. Leptin acts on the hypothalamus to promote satiety.
Klein MS, Shearer J. Metabolomics and type 2 diabetes: translating basic research into clinical application. J Diabetes Res. 2016;2016:3898502. doi:10.1155/2016/3898502; [Epub 2015 Nov 9].
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Upon completion of this chapter the student should be able to answer the following questions: 1.
Describe the pool of serum calcium and phosphate, including ionized, complexed, and protein bound. Describe the normal concentration ranges of these ions and the major routes of influx and efflux.
2.
Discuss the role of the parathyroid gland in the regulation of serum calcium and explain the role of the calcium-sensing receptor in the regulation of parathyroid hormone (PTH) secretion.
3.
Describe the production of 1,25-dihydroxyvitamin D, including sources of vitamin D precursor, sites and key regulators of vitamin D hydroxylation, and transport of vitamin D metabolites in the blood.
4.
List the target organs of PTH and describe its effects on calcium and phosphate mobilization or handling at each of these sites.
5.