Diabetes mellitus – the most common endocrine disorder – affects more than 25 million people in the U.S., which equates to 7 percent of the population.1,2 While this may not sound like a strikingly high number to some, nurses should emphasize to patients that diabetes is a major cause of heart disease – the No. 1 cause of death in the U.S.
Type 2 diabetes is the most common form of diabetes; the other two forms are type 1 and gestational. It’s believed that with type 2 diabetes, cells become resistant to the effects of insulin, leading to a rise in blood glucose levels.
Obese people have a greater risk of developing type 2 diabetes. Thus, along with the increase in childhood obesity, there also has been a rise in individuals under age 20 with diabetes. In 2010, the number grew close to 2 million.2 Weight reduction and exercise are the first-line treatment for obese patients with diabetes.3
Some lay people refer to diabetes as “sugar diabetes.” While this reference may sound sweet, the complications associated with diabetes are not. Individuals with diabetes have a greater risk of going blind, developing renal failure or neuropathy, or needing a lower-limb amputation. Studies have shown that greater control of blood sugar levels could help prevent potential complications related to diabetes.4
Patient education is key to achieving glycemic control and preventing diabetes-related complications. Nurses should have a strong knowledge base regarding treatment strategies for diabetes and associated risks in order to effectively educate patients and improve clinical outcomes.
If HbA1c levels indicate type 2 diabetes has not been controlled with diet and exercise alone, medications may be added to a patient’s treatment regimen. Although pharmacotherapy for diabetes includes various types of insulin, this article will focus on the oral medications used to treat type 2 diabetes.
Currently, there are six classifications of oral anti-diabetic medications used to manage type 2 diabetes: alpha-glucosidase inhibitors, biguanides, dipeptidyl peptidase-4 inhibitors, meglitinides, sulfonylureas and thiazolidinediones. These drugs could help normalize blood glucose levels and decrease diabetes-related complications.
However, these drugs may not be safe to use in some individuals and could cause harmful side effects. Nurses should be knowledgeable regarding the risks and benefits associated with anti-diabetic medications and comfortable with sharing this information with patients.
People with type 2 diabetes may observe that after eating their post-prandial blood sugar level rises significantly. That’s because alpha-glucosidase, an intestinal enzyme, breaks down complex carbohydrates into simple sugars such as glucose. Glucose, a monosaccharide, is then readily absorbed into the blood stream. With insulin resistance, glucose levels are able to rise significantly following a meal.
To help lower post-prandial blood sugar levels, some patients are prescribed alpha-glucosidase inhibitors such as acarbose (Precose) or miglitol (Glyset). Patients take these drugs with the first bite of a meal. This class of drugs delays carbohydrate digestion and decreases the amount of glucose absorbed into the blood stream following a meal. Prior to administering this drug, nurses should confirm patients do not have a history of bowel, renal or liver disease. If the patient does, the prescriber should be notified.
Patients taking alpha-glucosidase inhibitors should be instructed on potential adverse effects. Since this medication doesn’t enhance insulin secretion, it shouldn’t cause hypoglycemia alone. However, it may be combined with a medication like a sulfonylurea that does. Therefore, it is imperative nurses inform patients of the risk for hypoglycemia.
In addition, patients should know if they experience hypoglycemia, glucose gel or tablets are needed to quickly raise their blood sugar. Sucrose or table sugar, a disaccharide, may not work as quickly since the mechanism of alpha-glucosidase inhibitors is to slow the breakdown of this type of carbohydrate.
Besides monitoring blood sugar levels, routine monitoring of serum transaminases (alanine transaminase [ALT] and aspartate transaminase [AST]) is indicated as well. That’s because these drugs could potentially affect the liver. When taking this class of medication, patients may complain of side effects such as stomach pain, diarrhea and bloating even if they follow a diabetic diet. If symptoms are distressing, patients may have to temporarily hold or discontinue the medication. Nurses should stress to patients the importance of keeping their follow-up appointments with healthcare providers.
Nurses may observe many people with type 2 diabetes are taking biguanides. That’s because the American Diabetes Association recommends this drug as a first-line agent when diet and exercise fail to control blood sugar levels.3
The only biguanide available in the U.S. is metformin, which comes in a tablet form (Glucophage) or an oral solution (Riomet). It’s believed metformin lowers blood glucose levels by decreasing hepatic gluconeogenesis and increasing insulin uptake by peripheral tissue. Patients may like that this medication also could improve cholesterol levels and help them lose weight.
Like alpha-glucosidase inhibitors, metformin does not increase insulin secretion. Therefore, it shouldn’t cause hypoglycemia alone. However, when combined with medications that increase insulin secretion, the risk of hypoglycemia is heightened.
Prior to administering metformin, nurses should be aware of potential adverse effects and instruct patients of the same. Patients may verbalize common gastrointestinal complaints such as nausea, bloating and diarrhea. However, more serious side effects such as lactic acidosis could occur.5
Metformin is excreted by the kidneys and patients with renal insufficiency could experience drug accumulation. When drug levels rise, hepatic metabolism of lactate may be impaired; this increases the risk of lactic acidosis. Prior to administration, nurses should be aware of the patient’s creatinine level, and should question patients regarding metformin use prior to surgery or procedures requiring contrast agents. Patients who take metformin have an increased risk of lactic acidosis in the setting of impaired tissue perfusion or with the use of intravenous radiologic contrast agents. Metformin should be stopped for 48 hours following the use of iodinated contrast material.5
In addition, patients should be aware of signs of acidosis such as dizziness, tachycardia, palpitations, nausea, vomiting and hyperventilation, and understand they should seek medical attention if these symptoms occur. The use of alcohol should be avoided when taking metformin.
Dipeptidyl peptidase-4 inhibitors, commonly referred to as DPP-4 inhibitors, are another class of drugs used to improve glycemic control in patients with type 2 diabetes. Drugs in this category include sitagliptin (Januvia), saxagliptin (Onglyza) and linagliptin (Tradjenta).
In response to food intake, the body’s concentration of incretin hormones increases. Incretin hormones increase the release of insulin from pancreatic beta-cells, which helps lower blood glucose levels. However, incretin hormones are inactivated by DPP-4 enzymes. DPP-4 inhibitors work by slowing the inactivation of incretin hormones. This results in an increased concentration of incretin, which leads to increased glucose-dependent insulin secretion and a reduction in fasting and postprandial serum glucose levels.
Potential adverse effects associated with DPP-4 inhibitors include acute pancreatitis and hypersensitivity reactions.5 Patients should be assessed for abdominal pain and signs of anaphylactic reactions, and instructed to seek medical attention should these adverse effects occur. Nurses should hold the medication if any adverse effects are suspected.
When used alone, DPP-4 inhibitors may not cause hypoglycemia. However, when combined with a sulfonylurea, patients have a greater risk of developing hypoglycemia.
Meglitinides are a class of medications that also help to lower blood sugar in type 2 diabetes. Repaglinide (Prandin) and nateglinide (Starlix) are the only meglitinides available in the U.S. Following a meal, these drugs promote beta-cell secretion of insulin and increase insulin levels. Thus, these drugs could lower glucose levels and result in hypoglycemia.
While the amount of insulin released when meglitinides is used depends on the patient’s glucose level, nurses should still confirm that those taking these drugs can verbalize the signs. To help reduce the risk of hypoglycemia, patients should be instructed to take these medications within 30 minutes of a meal, and if they skip a meal, they should skip this medication as well.5 Patients should be reminded that drinking alcohol or engaging in strenuous physical exercise also could increase their risk of developing hypoglycemia. In addition, they should be instructed to have glucose readily accessible in case they experience signs of hypoglycemia such as dizziness, palpitations, trembling, diaphoresis, nausea or weakness.
Sulfonylureas have been available longer than all the other drug classes mentioned so far. While the first generation of these medications may not be as widely used as the second generation, nurses may find that this class of drugs is commonly prescribed to achieve glycemic control.
First-generation sulfonylureas consist of chlorpropamide (Diabinese), tolbutamide and tolazamide. Second-generation medications include glimepiride (Amaryl), glipizide (Glucotrol) and glyburide (Micronase, DiaBeta and Glynase).
Sulfonylureas increase the endogenous release of insulin. Therefore, these medications can increase a patient’s risk of hypoglycemia and as a result have been termed oral hypoglycemic agents. Since these drugs increase insulin secretion and insulin is lipogenic, this class of medications may contribute to weight gain. Nurses also should note that over time these medications may fail to maintain adequate glucose levels despite drug compliance because of a decline in beta-cell function. This necessitates the addition of a second anti-diabetic agent.
The dose of sulfonylureas may have to be reduced in patients with liver disease. Patients should be instructed to report abdominal discomfort, dark urine or light-colored stools or rash.5 In addition, although the second generation of sulfonylureas could carry less of a risk for causing disulfiram-like (Antabuse) reactions, certain agents like sulfonamides and salicylates could increase this risk. Patients should be instructed to avoid alcohol and inform their healthcare provider if they experience a disulfiram reaction. Symptoms include flushing, dizziness and tachycardia.
The last class of oral anti-diabetic medications, thiazolidinediones consist of pioglitazone (Actos) and rosiglitazone (Avandia). These drugs, also referred to as TZDs, work by improving insulin sensitivity in peripheral tissues. They increase glucose uptake and decrease glucose production by the liver, which helps improve blood glucose levels.
In the past two years, the Food and Drug Administration has added a “black box warning” to each of these medications. Patients should be informed of the increased risk of bladder cancer associated with using Actos for more than 1 year.6 Actos should not be used in patients being treated for bladder cancer. Avandia has been linked to increased risk of heart attacks and strokes, and is no longer available through retail pharmacies. Patients on Avandia now must be enrolled in a special program.6
Although these medications are associated with serious side effects, nurses may still encounter patients taking one of these drugs and they should be prepared to educate them accordingly.
Thiazolidinediones could cause liver complications and worsen heart failure.5 Before administering this medication, nurses should consider the patient’s ALT and AST levels and assess the person’s liver and heart. Patients should be instructed to seek medical attention if they notice signs of liver impairment such as nausea, vomiting, anorexia, dark-colored urine or stomach pain. Patients with heart failure should report any increase in shortness of breath, edema, cough or fatigue.
Risks & Benefits
Nurses should emphasize that dietary adherence and exercise play an important role in achieving glycemic control. However, when blood sugar levels are less than optimal or HbA1c levels are greater than 7 percent in spite of diet and exercise, patients have a greater risk for developing complications such as retinopathy, nephropathy, neuropathy and heart disease. To help reduce the risk of these life-altering complications, medications are available.
Nurses should be aware that although medications could potentially help patients achieve target blood sugar levels, inherent risks come with these drugs as well. To promote favorable outcomes, nurses should be prepared to assess patients’ level of knowledge regarding drug therapy and educate them accordingly so they can reach their targeted HbA1c level safely.
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