NR 601 Final Exam Study Guide

Week 5: Glucose metabolism disorders

Types of DM

1. Type 1- severe insulin deficiency resulting in reduction or absence of functioning beta cells in the pancreatic islets of Langerhans.  Autoimmune disorder which immune system attacks beta cells of the pancreas. This leads to hyperglycemia due to altered metabolism of lipids, carbs, and proteins.   Initial s/s of hyperglycemia.  Subjective findings- polyuria, polydipsia, nocturnal enuresis and polyphagia with paradoxical weight loss, visual changes and fatigue.

Objective-dehydration (poor skin turgor and dry mucous), wt loss despite normal/increase appetite, reduction in muscle mass. DKA-fatigue, cramping, abnormal breathing

**3 main ways someone with diabetes will present before diagnosed: Acute, subacute, and asymptomatic.

--Acute- This is the most severe presenting situation and can be life threatening for both type I and type II diabetes. This individual becomes very sick over a relatively short period of time, usually only a couple of days. Now symptoms will include things like nausea, vomiting, and abdominal pain and this often results in severe dehydration, and as such the individual may even become confused or unconscious as a result. In type I diabetes, this is known as diabetic ketoacidosis, or DKA for short. And it is how about 30% of individuals with type I diabetes will initially present before diagnosis. In type II diabetes, the acute presentation has a much longer name. It's known as hyperosmolar nonketotic state, or HHNS for short, and it's much less common than DKA as it's the initial presentation for only about 2% of individuals with type II diabetes. Now the difference between DKA and HHNS has to do with the difference between the underlying mechanisms of type I diabetes and type II diabetes. Now the most important difference is that in DKA the individual will become acidotic due to the production of ketoacids, hence the name diabetic ketoacidosis as opposed to hyperosmolar nonketotic state where ketoacids are not produced. 

--Subacute- mild to moderate presentation that occurs over a period of weeks to months. And these individuals or maybe someone close to them notice that they are generally just not feeling as well as they normally do and they may experience symptoms of fatigue, increased thirst, frequent urination, or even weight loss. Now, once again this can occur with either type I or type II diabetes. And in type I diabetes, this is the most common form of presentation before diagnosis, accounting for about 70% of individuals with type I diabetes. In type II diabetes, this is also common, however the predominant symptoms are a little bit more vague and weight loss is less common.

--Asymptomatic- individuals with diabetes can present is through asymptomatic screening tests. So type II diabetes affects nearly 10% of the population, and due to this high prevalence, potentially severe complications, and the relative ease of treatment, most adults, especially those with the risk factors of type II diabetes should be routinely screened for the disease. And this is the most common means by which type II diabetes is diagnosed. However, it's rare for the diagnosis of type I diabetes as routine screening for type I diabetes is not usually performed.

2. Type 2- Type 2 DM is characterized by the abnormal secretion of insulin, resistance to the action of insulin in the target tissues, and/or an inadequate response at the level of the insulin receptor. in Type II diabetes as well as drug-induced and gestational diabetes, the pancreas continues to secrete insulin. However, it's the cells throughout the body that are unable to adequately respond to it. So in a sense, these mechanisms inhibit the second step in the insulin pathway. And this is known as insulin resistance, which can be thought of as a relative insulin deficiency. A patient may, however, present with pruritus, fatigue, neuropathic complaints such as numbness and tingling, or blurred vision. More likely to have HHNS (Hyperosmolar hyperglycemic nonketotic syndrome) which is similar to DKA.

3. Prediabetic- fasting glucose consistently elevated above the normal range but less than 100-125. Impaired glucose tolerance (IGT) state of hyperglycemia where 2 hr post glucose load glycemic level is 140-199. RANDOM glucose test cannot be used to diagnose pre-diabetes. Needs to be fasting or two-hour glucose tolerance test. A1c greater than 5.7%. Fasting blood glucose greater than 100 but less than 126. OGTT greater than 140 but less than 200.

Diagnostic criteria- Diagnosis is made in combination of BOTH presentation and diagnostic tests. So first, if an individual has symptoms of diabetes, whether acute or subacute, then only one positive test, either the blood glucose or the hemoglobin A1C is necessary for the diagnosis of diabetes mellitus. However, if the individual is asymptomatic, then a diagnosis of diabetes mellitus requires two positive tests that are separated by at least one week of time.

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