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Type 2 diabetes mellitus (T2DM) is characterized by a progressive failure of pancreatic β-cell function (BCF) with insulin resistance. Once insulin over-secretion can no longer compensate for the degree of insulin resistance, hyperglycemia becomes clinically significant and deterioration of residual β-cell reserve accelerates. This pathophysiology has important therapeutic implications. Ideally, therapy should address the underlying pathology and should be started early along the spectrum of decreasing glucose tolerance in order to prevent or slow β-cell failure and reverse insulin resistance. The development of an optimal treatment strategy for each patient requires accurate diagnostic tools for evaluating the underlying state of glucose tolerance. This review focuses on the most widely used methods for measuring BCF within the context of insulin resistance and includes examples of their use in prediabetes and T2DM, with an emphasis on the most recent therapeutic options (dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists). Methods of BCF measurement include the homeostasis model assessment (HOMA); oral glucose tolerance tests, intravenous glucose tolerance tests (IVGTT), and meal tolerance tests; and the hyperglycemic clamp procedure. To provide a meaningful evaluation of BCF, it is necessary to interpret all observations within the context of insulin resistance. Therefore, this review also discusses methods utilized to quantitate insulin-dependent glucose metabolism, such as the IVGTT and the euglycemic-hyperinsulinemic clamp procedures. In addition, an example is presented of a mathematical modeling approach that can use data from BCF measurements to develop a better understanding of BCF behavior and the overall status of glucose tolerance.

Purpose: The purpose of this article is to review clinical issues related to the management of hyperglycemia in older patients with diabetes of long duration., Conclusion: Older adults represent an extensive proportion of patients with type 2 diabetes. Treatment goals need to be individualized to take into account comorbid conditions, life expectancy, diabetes complications, and the benefits of glycemic control. For both older patients and especially those with chronic renal insufficiency, the most important drug-related adverse effect to avoid is hypoglycemia, and avoidance of any severe hypoglycemia should be paramount. Patients with long duration of diabetes are often treated with insulin. Recent data show that glucagon-like peptide-1 receptor agonists may be used in combination with insulin for patients not achieving glycemic goals, with reductions in the doses of insulin used and with a low risk of hypoglycemia and possible weight loss.

The prevalence of diabetes mellitus (DM) increased by 49% between 1990 and 2000, reaching nearly epidemic proportions. In 2010, DM (type 1 or 2) was estimated to affect nearly 30% (10.9 million) of people 65 years and older and 215,000 of those younger than 20 years. Macrovascular and microvascular complications can occur; DM is a major cause of heart disease and stroke, and is the seventh leading cause of death in the United States. Based on 2007 data, the economic impact of DM is considerable, with total costs, direct medical costs, and indirect costs estimated at $174 billion, $116 billion, and $58 billion, respectively. Normal glucose regulation is maintained by an intricate interaction between pancreatic β-cells (insulin/amylin), pancreatic α-cells (glucagon), and associated organs (eg, intestines, liver, skeletal muscle, adipose tissue). Newly elucidated mechanisms include the involvement of the kidneys in glucose regulation, as well as central glucose regulation by the brain. The central defects in type 2 diabetes mellitus (T2DM) are decreased insulin secretion, glucoregulatory hormone deficiency/resistance, and insulin resistance, resulting in abnormal glucose homeostasis. This article provides an extensive review of mechanisms involved in physiologic blood glucose regulation and imbalances in glucose homeostasis.

While not traditionally discussed, the kidneys' contributions to maintaining glucose homeostasis are significant and include such functions as release of glucose into the circulation via gluconeogenesis, uptake of glucose from the circulation to satisfy their energy needs, and reabsorption of glucose at the level of the proximal tubule. Renal release of glucose into the circulation is the result of glycogenolysis and gluconeogenesis, respectively involving the breaking down and formation of glucose-6-phosphate from precursors (eg, lactate, glycerol, amino acids). With regard to renal reabsorption of glucose, the kidneys normally retrieve as much glucose as possible, rendering the urine virtually glucose free. The glomeruli filter from plasma approximately 180 grams of D-glucose per day, all of which is reabsorbed through glucose transporter proteins that are present in cell membranes within the proximal tubules. If the capacity of these transporters is exceeded, glucose appears in the urine. The process of renal glucose reabsorption is mediated by active (sodium-coupled glucose cotransporters) and passive (glucose transporters) transporters. In hyperglycemia, the kidneys may play an exacerbating role by reabsorbing excess glucose, ultimately contributing to chronic hyperglycemia, which in turn contributes to chronic glycemic burden and the risk of microvascular consequences. This article provides an extensive review of the kidneys' role in normal human physiology, the mechanisms by which they contribute to glucose regulation, and the potential impact of glucose imbalance on the kidneys.