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 Trijardy XR (Boehringer Ingelheim/Lilly), a fixed-dose combination of the sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin, the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin, and extended-release metformin, for oral treatment of type 2 diabetes in adults. Empagliflozin and linagliptin have been available in a fixed-dose combination as Glyxambi since 2015, and both have been available in 2-drug combinations with extended-release metformin for years (see Table 1).

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.

An oral formulation of the glucagon-like peptide-1 (GLP-1) receptor agonist semaglutide (Rybelsus – Novo Nordisk) has been approved by the FDA for once-daily treatment of type 2 diabetes in adults. Semaglutide, which has been available in a subcutaneously-injected formulation (Ozempic) since 2017, is the first GLP-1 receptor agonist to become available for oral administration; the 4 other GLP-1 receptor agonists currently available in the US are administered by subcutaneous (SC) injection.

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.

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 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 oral biguanide metformin (Glucophage, and others) is generally the drug of choice for initial treatment of type 2 diabetes. It has also been used to prevent or at least delay the onset of diabetes in patients considered to be at high risk for the disease. Recent guidelines recommend considering use of metformin in patients with prediabetes (fasting plasma glucose 100-125 mg/dL, 2-hr post-load glucose 140-199 mg/dL, or A1C 5.7-6.4%), especially in those who are <60 years old, have a BMI >35 kg/m², or have a history of gestational diabetes. Metformin has not been approved for such use by the FDA.

The FDA has approved Jentadueto XR (Boehringer Ingelheim/Lilly), a once-daily extended-release formulation of the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin and the biguanide metformin, for oral treatment of type 2 diabetes. Linagliptin and metformin have been available for years in a twice-daily immediate-release combination (Jentadueto). Once-daily extended-release formulations combining metformin with the DPP-4 inhibitors saxagliptin (Kombiglyze XR) and sitagliptin (Janumet XR) are also available.

The FDA has required labeling changes that replace serum creatinine (SCr) with estimated glomerular filtration rate (eGFR) as the parameter used to determine the appropriateness of treatment with the biguanide metformin (Glucophage, and others) in patients with renal impairment. These changes will allow more patients with mild to moderate renal impairment to receive metformin, which is generally the first drug prescribed for treatment of type 2 diabetes.

Metformin was previously contraindicated in women with a SCr level ≥1.4 mg/dL and in men with a SCr level ≥1.5 mg/dL, but use of SCr as a surrogate indicator tends to underestimate renal function in certain populations (e.g., younger patients, men, black patients, patients with greater muscle mass). The calculation of eGFR takes into account age, race, and sex, as well as SCr level, providing a more accurate assessment of kidney function. A literature review summarized in an FDA Drug Safety Communication concluded that, based on eGFR, metformin is safe to use in patients with mild renal impairment and in some patients with moderate renal impairment.1

The eGFR should be calculated before patients begin treatment with metformin and at least annually thereafter. Metformin is now contraindicated in patients with an eGFR <30 mL/min/1.73 m², and starting treatment with the drug in patients with an eGFR between 30 and 45 mL/min/1.73 m² is not recommended. If the eGFR falls below 45 mL/min/1.73 m² in a patient already taking metformin, the benefits and risks of continuing treatment should be assessed. Metformin should be not be administered for 48 hours after an iodinated contrast imaging procedure in patients with an eGFR <60 mL/min/1.73 m² or a history of liver disease, alcoholism, or heart failure, or in those receiving intra-arterial contrast, and the eGFR should be re-evaluated before treatment is restarted.

1. FDA Drug Safety Communication: FDA revises warnings regarding use of the diabetes medicine metformin in certain patients with reduced kidney function. Available at: www.fda.gov. Accessed April 14, 2016.

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The FDA has approved Synjardy (Boehringer Ingelheim/Lilly), a fixed-dose combination of the sodium-glucose co-transporter 2 (SGLT2) inhibitor empagliflozin (Jardiance) and metformin (Glucophage, and others), for treatment of patients with type 2 diabetes not adequately controlled on either of these drugs alone or already being treated with both empagliflozin and metformin. It is the third SGLT2 inhibitor/metformin combination to be approved in the US.

Adults with a body mass index (BMI) between 25 and 29.9 kg/m² are considered overweight. Those with a BMI ≥30 are considered obese. Losing even a small amount of weight and increasing physical activity can prevent some of the complications of obesity, particularly type 2 diabetes. Diet and exercise are the preferred methods for losing weight, but long-term failure rates are high. Several drugs have been approved by the FDA for weight reduction, but adherence is poor, adverse effects are common, and patients usually regain the lost weight when the drug is stopped. Bariatric surgery can produce substantial weight loss and significantly reduce obesity-related comorbidities; long-term data on its safety are encouraging, but still limited. Guidelines for the management of overweight or obese adults have recently been published.

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.

Linagliptin (Tradjenta) and metformin (Glucophage, and others) are now available as a fixed-dose combination (Jentadueto – Boehringer Ingelheim/Lilly) for oral treatment of type 2 diabetes in adults. Metformin is generally the preferred first-line agent for treatment of type 2 diabetes, but most patients eventually require treatment with multiple drugs. Linagliptin is a dipeptidyl peptidase-4 (DDP-4) inhibitor like sitagliptin (Januvia) and saxagliptin (Onglyza). Both sitagliptin and saxagliptin are also available in fixed-dose combinations with metformin.

The FDA has approved Juvisync (Merck), a fixed-dose combination of the antihyperglycemic DPP-4 inhibitor sitagliptin (Januvia) and the HMG-CoA reductase inhibitor simvastatin (Zocor, and others).

Infertility occurs in about 15% of couples. About one-third of cases are due to problems with ovulation or other female factors, another third are due to a male infertility factor, and the remaining third are unexplained. In older women, unexplained infertility is probably caused by diminished quality and quantity of oocytes. The first approach to treatment of female-factor infertility generally is the use of drugs that stimulate oocyte production.

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.

Liraglutide (Victoza – Novo Nordisk), a glucagon-like peptide-1 (GLP-1) receptor agonist given by subcutaneous injection, has been approved by the FDA for treatment of patients with type 2 diabetes. It can be used alone or in addition to oral antidiabetic drugs such as metformin (Glucophage, and others) or glimepiride (Amaryl, and others). Liraglutide is not recommended for first-line therapy and is not approved for use with insulin.

The cardiovascular safety of the thiazolidinedione rosiglitazone (Avandia – GlaxoSmithKline) is in the news again, with some authorities calling for its removal from the market (New York Times, February 19, 2010).

Saxagliptin (Onglyza - Bristol-Myers Squibb), the second oral dipeptidyl peptidase-4 (DPP-4) inhibitor to be marketed in the US, has been approved by the FDA for treatment of adults with type 2 diabetes.

A new fixed-dose tablet (PrandiMet - Novo Nordisk) combining metformin (Glucophage, and others) and repaglinide (Prandin) has been approved by the FDA for treatment of type 2 diabetes in patients already taking both metformin and repaglinide, or for patients not adequately controlled on either drug alone.

The development of hyperglycemia in type 2 diabetes results from a combination of metabolic abnormalities including 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.

Colesevelam (Welchol - Daiichi Sankyo - Med Lett Drugs Ther 2000; 42:102), a bile-acid sequestrant used to lower LDL cholesterol, has been approved by the FDA as an adjunct to diet and exercise in the treatment of type 2 diabetes. In unpublished studies summarized in the package insert, patients with type 2 diabetes taking metformin (Glucophage, and others), a sulfonylurea or insulin (each as either monotherapy or in combination with other anti-diabetic agents) were given colesevelam 3800 mg per day or placebo; colesevelam significantly reduced glycosylated hemoglobin (A1c) by about 0.5% more than placebo in all three trials. The mechanism is unclear.

Colesevelam can cause constipation, nausea and dyspepsia, increase serum triglyceride concentrations, and interfere with absorption of other oral drugs. One month's treatment with Welchol obtained from drugstore.com would cost about $200. Medical Letter consultants are not enthusiastic about prescribing it for this indication.

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Losing even a small amount of weight and increasing physical activity can prevent some of the complications of obesity, particularly type 2 diabetes. Diet and exercise are the preferred methods for losing weight but are associated with high long-term failure rates. Drugs may help some patients, but all currently available drugs for weight reduction have drawbacks. Gastric surgery can produce marked weight loss in the severely obese, but long-term data on safety are limited.

Sitagliptin (Januvia) and metformin (Glucophage, and others) are now available in a single tablet (Janumet - Merck) for treatment of type 2 diabetes. The combination is approved by the FDA for use in patients not adequately controlled by sitagliptin or meformin alone or in those already taking both drugs. Metformin is also available in combination with the thiazolidinediones pioglitazone and rosiglitazone and with the sulfonylureas glipizide and glyburide.

For patients with diabetes poorly controlled with a single oral drug, addition of a second drug with a different mechanism can be helpful. A fixed-dose combination (Actoplus met - Takeda) of two widely used antihyperglycemic drugs, the thiazolidinedione pioglitazone (Actos) and the biguanide metformin (Glucophage, and others), has been approved by the FDA for management of type 2 diabetes. It is indicated for patients already being treated with both pioglitazone and metformin or as second-line therapy for those not adequately controlled with either metformin or pioglitazone alone. Rosiglitazone, another thiazolidinedione, is also available in a fixed-dose combination with metformin (Avandamet).

The development of hyperglycemia in type 2 diabetes results from a combination of metabolic abnormalities including insulin resistance, excess hepatic glucose production and diminished insulin secretion. In many patients, diet and regular exercise can improve glucose control. Most drugs currently available for management of type 2 diabetes increase insulin supply (sulfonylureas, other secretagogues and insulin itself), decrease insulin resistance (thiazolidinediones) or improve the effectiveness of insulin (biguanides). Alpha-glucosidase inhibitors reduce the rate of glucose absorption. Newer agents such as pramlintide (Symlin) and exenatide (Byetta) have multiple effects to increase satiety and reduce postprandial hyperglycemia.

Exenatide injection (Byetta - Amylin/Lilly), a synthetic peptide that stimulates release of insulin from pancreatic beta cells, has been approved by the FDA as adjunctive therapy for patients with type 2 diabetes who have not achieved optimal glycemic control on metformin (Glucophage, and others), a sulfonylurea, such as glyburide (DiaBeta, and others), or both. Exenatide is not indicated for use with insulin.

Trospium chloride (Sanctura - Indevus/Odyssey) has been approved by the FDA for treatment of overactive bladder with symptoms of urge urinary incontinence, urgency and urinary frequency. It has been available in Europe for many years.

The latest definitions of overweight and obesity are based on body mass index (BMI). The BMI is calculated by dividing the weight in kilograms by the square of the height in meters (kg/m²). More than half of American adults are considered overweight with a BMI of ≥25, and about one third are obese with a BMI of ≥30. All ages seem to be affected; the proportion of children and adolescents who are overweight has more than doubled in the past 25 years. There is no lack of effort to treat obesity: drugs, diets and programs to change lifestyle are the basis for a large and flourishing industry. The frequent failure of diet and drug treatment sometimes leads to recommendations for surgery, usually restricted to those with a BMI ≥40.

Infertility occurs in about 15% of couples. About one third of infertility is due to problems with ovulation or an anatomic abnormality of the fallopian tube or peritoneum, such as scarring, adhesions or endometriosis. Another third is due to a male infertility factor, most commonly insufficient sperm production or abnormal motility or morphology. The remaining third is unexplained. In older women unexplained infertility is probably caused by diminished quality and quantity of oocytes, decreased implantation and spontaneous pregnancy wastage.

Polycystic ovary syndrome (PCOS), an endocrine abnormality characterized by hyperandrogenism and anovulation, affects 5-10% of women of reproductive age in the US. It is often accompanied by obesity and insulin resistance. In recent years, antidiabetic drugs, although not approved for such use by the FDA, have been tried for treatment of this disorder. This review describes the effectiveness of metformin and the thiazolidinediones in women with PCOS. Also included is a dosage and cost table for some insulin-sensitizing drugs.

Two new fixed-dose combinations are now available for management of type 2 diabetes. Metaglip (Bristol-Myers Squibb), a combination of metformin and glipizide, is approved for initial therapy or as second-line treatment when control is not adequate on metformin or a sulfonylurea alone. Avandamet (GlaxoSmithKline), a combination of metformin and rosiglitazone, is approved by the FDA only as second-line therapy for patients who are not well controlled on metformin alone, or are already taking both metformin and rosiglitazone. Glucovance (Bristol-Myers Squibb), a combination of metformin and glyburide, a sulfonylurea similar to glipizide, has been available since 2000 (Medical Letter 2000; 42:105).

The development of hyperglycemia in type 2 diabetes results from a combination of metabolic abnormalities including insulin resistance, excess hepatic glucose production and diminished insulin secretion. Most drugs currently available for management of type 2 diabetes fall into 2 categories: those that increase insulin supply (sulfonylureas, other secretagogues and insulin itself) and those that decrease insulin resistance or improve its effectiveness (biguanides, thiazolidinediones). Alpha-glucosidase inhibitors reduce the rate of glucose absorption.

Nateglinide (Starlix), a new meglitinide oral glucose-lowering agent, has been approved by the FDA.

A fixed-dose combination of two antihyperglycemic drugs, glyburide and metformin, has been approved by the US FDA for initial treatment of type 2 diabetes or when glucose control is unsatisfactory with either drug alone

Bexarotene, a retinoid analog, has been approved by the US Food and Drug Administration for oral treatment of dermatologic manifestations of refractory cutaneous T-cell lymphoma.

Pioglitazone is the third thiazolidinedione ("glitazone") to be marketed in the USA for treatment of type 2 diabetes. Thiazolidinediones decrease resistance to insulin.

Rosiglitazone, the second thiazolidinedione derivative to be marketed in the USA for treatment of type 2 diabetes, has been approved by the FDA for use either alone or combined with meformin.

Miglitol, an oral alpha-glucosidase inhibitor similar to acarbase, is now available for treatment of type 2 diabetes.

Repaglinide (Prandin - Novo Nordisk) is a new oral glucose-lowering agent for treating type 2 diabetes (formerly called non-insulin-dependent diabetes mellitus or NIDDM). It has been approved by the FDA for monotherapy or for use in combination with metformin.

Midodrine hydrochloride (ProAmatine - Roberts), an alpha1-selective adrenergic agonist, is now available for treatment of severe symptomatic orthostatic hypotension. Other treatments for this condition include other sympathomimetics, constrictive garments, erythropoietin (Epogen; Procrit) and fludrocortisone with salt (D Robertson and TL Davis, Neurology, 45 suppl 5: S26, 1995).

Troglitazone (Rezulin - Parke-Davis), the first of a new class of thiazolidinedione derivatives ('glitazones') for diabetes, has been marketed for oral treatment of noninsulin- dependent diabetes mellitus (NIDDM) in patients who take more than 30 units of insulin daily and still have a glycosylated hemoglobin concentration (HbA1c) of 8.5% or higher.

Glimepiride (Amaryl - Hoechst Marion Roussel), a new sulfonylurea similar to glyburide and glipizide (Medical Letter, 26:79, 1984), was recently marketed for treatment of patients with non-insulin-dependent diabetes mellitus (NIDDM) not controlled by diet and exercise. The new drug is the first sulfonylurea approved by the US Food and Drug Administration (FDA) for use concurrently with insulin.

Acarbose (Precose -Bayer), an oral alpha-glucosidase inhibitor that has been available in Europe for several years, was recently approved by the US Food and Drug Administration (FDA) for treatment of non-insulin-dependent diabetes mellitus (NIDDM).

Metformin (Glucophage - Bristol-Myers Squibb), a hypoglycemic agent, was recently marketed in the USA for oral treatment of patients with non-insulin-dependent diabetes mellitus (NIDDM) not adequately controlled by diet alone. Previously marketed in more than ninety countries, including Canada, metformin (dimethylbiguanide) is chemically related to phenformin (phenylethylbiguanide), which was withdrawn from the US market in 1976 because it caused a high incidence of lactic acidosis. In approving metformin, the US Food and Drug Administration stipulated that a post-marketing controlled trial of 10,000 patients be conducted to determine the incidence of lactic acidosis.