View the Table: GLP-1 and GIP/GLP-1 Receptor Agonists for Type 2 Diabetes

The injectable glucagon-like peptide-1 (GLP-1) receptor agonist semaglutide (Wegovy) has been approved by the FDA to reduce the risk of major adverse cardiovascular events (MACE) in adults with established cardiovascular disease (CVD) and either obesity or overweight. Semaglutide is the first drug to be approved for cardiovascular risk reduction in this population. It is also approved in a lower-dose injectable formulation as Ozempic and in an oral formulation as Rybelsus (see Table 1).

Glucagon-like peptide-1 (GLP-1) receptor agonists and the dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonist tirzepatide (Mounjaro) are widely prescribed for treatment of type 2 diabetes and weight management (see Table 1), but they delay gastric emptying and commonly cause nausea and vomiting. Gastroparesis and bowel obstruction (ileus) have also been reported with their use.

The sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin has been available for years alone (Jardiance – Boehringer Ingelheim) and in combination with metformin (Synjardy) to improve glycemic control in adults with type 2 diabetes. Both products have now been approved for use in children ≥10 years old. Empagliflozin is the second oral drug to become available in the US for treatment of type 2 diabetes in children; metformin has been available since 2000 for this indication. The injectable glucagon-like peptide-1 (GLP-1) receptor agonists liraglutide (Victoza) and extended-release exenatide (Bydureon BCise) are also approved for use in children ≥10 years old.

Diet, exercise, and weight loss can improve glycemic control, but almost all patients with type 2 diabetes require antihyperglycemic drug therapy. Treating to a target A1C of <7% while minimizing hypoglycemia is recommended to prevent microvascular complications of diabetes (retinopathy, nephropathy, and neuropathy). An A1C target of <8% may be appropriate for some older patients.

The FDA has approved tirzepatide (Mounjaro – Lilly), a peptide hormone with activity at both glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors, to improve glycemic control in adults with type 2 diabetes. Tirzepatide, which is injected subcutaneously once weekly, is the first dual GIP/GLP-1 receptor agonist to become available in the US. Selective GIP receptor agonists are not available in the US; GLP-1 receptor agonists have been available for years.

Diet, exercise, and weight loss can improve glycemic control, but almost all patients with type 2 diabetes eventually require drug therapy. Treating to a glycated hemoglobin (A1C) concentration of <7% can prevent microvascular complications (retinopathy, nephropathy, and neuropathy), but whether it prevents macrovascular complications and death is unclear. An A1C target of <8% may be appropriate for older patients and those with underlying cardiovascular disease (CVD), a history of severe hypoglycemia, diabetes-related complications, a limited life expectancy, or a long duration of disease.

Since 2008, because of safety concerns, the FDA has mandated that long-term cardiovascular outcomes trials be conducted for all new drugs for type 2 diabetes. Reductions in the incidence of macrovascular complications in these trials with some sodium-glucose co-transporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists in patients at risk for cardiovascular disease (see Table 1) have led to new recommendations.

The FDA has approved semaglutide (Ozempic – Novo Nordisk), a long-acting injectable GLP-1 (glucagon-like peptide-1) receptor agonist, for once-weekly treatment of adults with type 2 diabetes. It is the sixth GLP-1 receptor agonist to be approved in the US.

The FDA has approved Xultophy 100/3.6 (Novo Nordisk), a fixed-ratio combination of insulin degludec and the GLP-1 (glucagon-like peptide-1) receptor agonist liraglutide, for once-daily treatment of adults with type 2 diabetes inadequately controlled on basal insulin (<50 units daily) or liraglutide (≤1.8 mg daily).

For many years, the goal of drug therapy for most patients with type 2 diabetes has been to achieve and maintain an A1C of <7%. Achieving that goal can prevent microvascular complications (diabetic retinopathy, nephropathy, neuropathy), but whether it prevents macrovascular complications (myocardial infarction [MI], stroke) has been less clear. The FDA now requires that cardiovascular safety studies be performed for all new drugs for type 2 diabetes.1 Recent findings that some of the newer second-line drugs for type 2 diabetes have cardiovascular benefits have led to new interest in the cardiovascular efficacy and safety of all antidiabetic drugs.

The FDA has approved lixisenatide (Sanofi), a short-acting injectable GLP-1 (glucagon-like peptide-1) receptor agonist, for once-daily treatment of adults with type 2 diabetes, both alone (Adlyxin) and in a fixed-ratio combination with insulin glargine (Soliqua 100/33). Lixisenatide has been available since 2013 in many other countries as Lyxumia. It is the fifth GLP-1 receptor agonist to be approved in the US.

The goal of drug therapy for type 2 diabetes is to achieve and maintain a near-normal glycated hemoglobin (A1C) concentration without inducing hypoglycemia; the target is generally an A1C of ≤7%. Treating to this target has been shown to prevent microvascular complications (retinopathy, nephropathy, and neuropathy), but whether it prevents macrovascular outcomes is unclear. An A1C target of <8% may be appropriate for older patients and those with underlying cardiovascular disease, a history of severe hypoglycemia, diabetes-related complications or comorbidities, or a long duration of disease.

The injectable glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide, previously approved by the FDA for treatment of type 2 diabetes as Victoza, has now also been approved at a higher dose as Saxenda (Novo Nordisk) for chronic weight management in adults with a BMI ≥30, or a BMI ≥27 with a weight-related comorbidity such as hypertension, dyslipidemia, or diabetes.

Two new injectable GLP-1 (glucagon-like peptide-1) receptor agonists, dulaglutide (Trulicity [trū li si tee] – Lilly) and albiglutide (Tanzeum [tan' zee um] – GSK), have been approved by the FDA for once-weekly treatment of type 2 diabetes. Other available GLP-1 receptor agonists include exenatide, which is approved for injection twice daily (Byetta) or once weekly (Bydureon), and liraglutide (Victoza), which is injected once daily.

The goal of drug therapy for type 2 diabetes is to achieve and maintain a near-normal A1C concentration without inducing hypoglycemia; the target is generally an A1C of <7.0%. Treating to this target has been shown to prevent the microvascular complications of retinopathy and nephropathy, but whether it prevents macrovascular outcomes remains unclear. Three large trials found that intensive glucose control did not reduce the incidence of macrovascular events. One of these trials (ACCORD) in >10,000 patients with type 2 diabetes, with or at high-risk for cardiovascular disease, found that treating patients intensively with antihyperglycemic drugs to an A1C target of 6.0% for a mean of 3.7 years did not significantly reduce the incidence of major cardiovascular events (the primary endpoint) and was associated with increased all-cause mortality compared to patients treated to an A1C target of 7.0-7.9%. An A1C target of 7-8% may be prudent in older patients and in those with underlying cardiovascular disease, severe hypoglycemia, or multiple diabetes-related complications or co-morbidities.

Canagliflozin (kan" a gli floe' zin; Invokana – Janssen), a sodium-glucose co-transporter 2 (SGLT2) inhibitor, has been approved by the FDA for oral treatment of type 2 diabetes.

Most experts agree that lifestyle modifications and metformin (Glucophage, and others) should be used first to treat patients with type 2 diabetes. If metformin alone fails to control hyperglycemia, there is no general agreement on which drug should be added next. A recent article in The Medical Letter offered some support for a sulfonylurea. Three recent trials published in The Lancet favored the long-acting basal insulin glargine, the glucagon-like peptide (GLP-1) analog exenatide, and the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin, respectively. Some of the advantages and disadvantages of these and other available agents are listed in Table 1 on the opposite page.

The FDA has approved a once-weekly extendedrelease formulation of exenatide (Bydureon – Amylin), an injectable glucagon-like peptide-1 (GLP-1) receptor agonist, for treatment of type 2 diabetes.

The development of hyperglycemia in type 2 diabetes results from a combination of metabolic abnormalities that includes insulin resistance, diminished insulin secretion and excess hepatic glucose production. Diet, exercise and weight loss are helpful in improving glucose control, but most patients ultimately require drug therapy.

Adults with a body mass index (BMI=kg/m²) of 25-<30 are considered overweight; those with a BMI of ≥30 are considered obese.