Antidiabetic Therapy - Non-Insulin and Oral Antidiabetic Drugs

Non-insulin antidiabetic medications are used to treat type 2 diabetes mellitus. These medications work to overcome insulin resistance and lower blood glucose levels. One of the most used oral antidiabetic medications is metformin, which is classified as a biguanide.

Now, type 2 diabetes mellitus is characterized by insulin resistance, which is when cells have difficulty responding to insulin in order to uptake glucose from the blood. As a result, cells starve because they don't receive adequate energy, despite the blood having high blood glucose levels. Metformin lowers blood glucose by decreasing glucose production in the liver, reducing glucose absorption in the gut, and increasing insulin sensitivity of targeted cells, like those in fat and skeletal muscle. As an added benefit, metformin decreases triglyceride and cholesterol production in the liver, which helps to reduce plasma lipid levels, as well as weight and blood pressure.

Okay, so, because metformin does not stimulate insulin release from pancreatic beta cells like other oral antidiabetic medications do, hypoglycemia is not one of its side effects. However, other side effects are common, including GI disturbances, such as anorexia, nausea, vomiting, and diarrhea. In addition, prolonged use of metformin decreases absorption of vitamin B12 which can lead to peripheral neuropathy.

Metformin also can impair mitochondrial oxidation of lactic acid, so, as a Black Box warning, metformin can lead to lactic acidosis, which is a life-threatening condition characterized by hyperventilation, myalgia, malaise, and drowsiness, and can lead to kidney failure, and shock. So, as far as contraindications go, metformin is contraindicated in patients with hypoglycemia, diabetic ketoacidosis, metabolic acidosis, and severe renal dysfunction. Additionally, metformin should be used cautiously in patients with alcoholism, liver impairment, and heart failure; and it is not indicated for patients with type 1 diabetes mellitus.

Importantly, metformin is considered a high alert medication, meaning that it has an increased risk of causing significant harm if used in error. Regarding interactions, metformin administration should be stopped 48 hours before and after procedures that require the administration of IV contrast dye, since it increases the risk of acute kidney failure and lactic acidosis. Patients should not consume alcohol while taking metformin, since alcohol inhibits the breakdown of lactic acid, which also increases the risk of lactic acidosis.

Okay, when caring for your patient taking metformin, begin by performing a baseline assessment including vital signs. Then, review their most recent laboratory test results, including blood glucose, hemoglobin A1c, and CBC, as well as renal and hepatic function tests. Following administration, assess for common side effects, and evaluate for the effectiveness of oral antidiabetic treatment.

Next, be sure to focus your patient education on safe self-administration. Teach them to take their medication exactly as prescribed and let them know that they can take their medication with food to minimize GI upset. Also be sure to emphasize that they should not abruptly stop taking their medication. Next, advise them to closely monitor their blood glucose levels, and to let their health care provider know if their medication regimen is not keeping their glucose levels within the desired range. Also be sure to encourage your patient to include foods that are high in vitamin B12 in their daily diet, such as fish, meat, poultry, eggs, and dairy products, since metformin can interfere with the absorption of this vitamin; and teach them to let their health care provider know if they experience symptoms of peripheral neuropathy, like numbness or tingling in their hands or feet. In addition, emphasize the importance of avoiding alcohol while taking metformin, since this increases the risk of lactic acidosis; and instruct them to let their health care provider know immediately if they experience symptoms of lactic acidosis like muscle pain or unusual lethargy.

Finally, review common side effects they may experience and remind them to keep all scheduled follow-up appointments.

Alright, as a quick recap.... Metformin is classified as a biguanide, and it's one of the most commonly used oral antidiabetic medications. Metformin works by decreasing glucose production in the liver, reducing glucose absorption in the gut, and increasing the insulin sensitivity of targeted cells.

Common side effects include GI disturbances, and it has a Black Box warning regarding an increased risk of lactic acidosis. Additionally, metformin administration should be stopped 48 hours before and after any procedures that require the use of IV contrast dye administration, since it increases the risk of developing acute kidney failure and lactic acidosis.

Nursing considerations for non-insulin antidiabetic medications include establishing a baseline assessment, monitoring for side effects, evaluating the effectiveness of therapy, and providing teaching for safe self-administration.