Antidiabetic Therapy - Insulin

Insulin is a medication most often used to treat type 1 diabetes mellitus but can also be used to treat type 2 diabetes mellitus during periods of stress, illness, or hospitalization, or when measures, like lifestyle changes and oral antidiabetic medications, fail to provide adequate glycemic control.

Now, there are 4 main types of insulin, which are classified based on their onset of action and duration of effect. These include rapid-acting; short-acting or regular; intermediate-acting; and long-acting insulins.

Additionally, there are various combinations of insulin, like a short-acting insulin combined with an intermediate-acting insulin.

Insulin can be administered as a basal dose to supply the insulin needed for basic metabolic functions, typically with an intermediate- or long-acting insulin. It can also be given as a bolus, like with a meal to cover the postprandial rise in glucose, usually with a rapid- or short-acting insulin. And it can be given as a correctional dose for acute episodes of hyperglycemia, typically with a rapid- or short-acting insulin.

Insulin is usually administered either subcutaneously or intravenously, but it also comes in a powdered form that can be inhaled.

Alright now, glucose is the body's essential energy source and is controlled by insulin, a hormone which is released from the beta cells in the pancreas in response to a rise of glucose. Type 1 diabetes occurs when the beta cells in the pancreas are unable to produce insulin; whereas type 2 occurs when there's insulin resistance, meaning cells have trouble responding to the insulin that is produced, so they aren't able use the available glucose from the blood, leading to cell starvation, despite a high circulating glucose level.

When administered, insulin binds to receptors on insulin-responsive tissues, mostly muscle and fat tissue, and facilitates the uptake of glucose from the blood. It also acts on the liver and muscles causing glycogenesis, or the storage of glucose as glycogen. In the liver and adipose tissue, insulin stimulates lipogenesis, or the synthesis of fatty acids; while in muscles, it promotes amino acid uptake and protein synthesis.

Now, the main side effect of insulin therapy is hypoglycemia, which can manifest as headache, dizziness, sweating, hunger, and weakness. Additionally, localized side effects from subcutaneous injections include redness, swelling, and itching. Repeated injections in the same site can also result in lipohypertrophy or an accumulation of subcutaneous fat, forming a raised lump; or lipoatrophy, where there's atrophy of the subcutaneous tissue that causes a depression in the skin.

Regarding interactions, certain medications like glucocorticoids can increase glucose levels, which could increase the need for additional insulin to control blood glucose. Conversely, beta blockers, like propranolol, impair glycogenolysis, so they can worsen insulin-induced hypoglycemia; and they can mask the signs associated with hypoglycemia.

Alright, insulin is contraindicated in patients with hypoglycemia, and precautions should be taken when administering insulin to patients with a high risk of hypoglycemia, such as a patient who's ordered to have nothing by mouth or has persistent vomiting. It should also be used with caution in patients with hepatic or renal disease.

Insulin that's administered intravenously can easily produce hypokalemia, as potassium shifts from the extracellular to the intracellular space, so patients at risk for hypokalemia, such as those also taking medications like loop diuretics, should be monitored closely.

Lastly, all insulin preparations are considered high alert medications, meaning they have an increased risk of causing significant harm if used in error.

Now, before administering insulin to your patient, be sure to obtain baseline vital signs and assess for indications of hypoglycemia. Then, review their recent laboratory test results, including their current blood glucose level, hemoglobin A1C, as well as their renal and hepatic function tests. If your patient will be receiving IV insulin, be sure to check their potassium level. While your patient is receiving insulin, assess for side effects, and evaluate the effectiveness of insulin therapy.

When educating your patient about insulin therapy, focus your teaching on safe self-administration. Review with your patient how to use their glucometer to check their blood glucose, and how to draw up their insulin or prepare their insulin pen. Show them the preferred injection sites and advise them to rotate the site regularly. Remind them to check their blood glucose before meals and at bedtime, and whenever they feel their glucose may be too high or too low. Be sure to instruct them to let their health care provider know if their medication regimen is not keeping their glucose level within the desired range. Finally, explain how to recognize signs and symptoms of hypoglycemia and hyperglycemia and how to respond.

Lastly, let your patient know that, in addition to their insulin, they should implement lifestyle changes to help manage their blood glucose, including regular exercise and following a diabetic diet that's low in carbohydrates and high in fiber.

Alright, as a quick recap…. Insulin is used to treat diabetes mellitus by binding to receptors on insulin-responsive tissues, mostly muscle and fat tissue, and facilitating the uptake of glucose from the blood. The main side effect of insulin is hypoglycemia. Nursing considerations for insulin therapy include establishing a baseline assessment, monitoring for side effects, evaluating the effectiveness of therapy, and providing teaching for safe self-administration.