How Do You Know Which Diabetes Drug Is Best for You?

The incidence of type 2 diabetes is rapidly rising, as has been well publicized in recent years. An estimated 30 million people in the US, or about 9.4% of the population, have it. That’s up from 2.5% in 1980. Some 1.5 million adults are newly diagnosed every year. An increasing number are younger than 40.

But, shockingly, despite widespread attention to the increase in diabetes, 1 in 3 people who have it have not been diagnosed. And many who have been diagnosed don’t get adequate treatment, according to numerous studies over the past decade.

That includes not being prescribed the right drug at the right dose. It also includes people who experience adverse effects from a diabetes drug and, as a result, stop taking it. On average, 10 to 20% of people with diabetes stop taking their pills due to side effects.

This article focuses on the pros and cons of the oral diabetes drugs. Almost all people with diabetes are candidates for one or more of these medicines — but with so many kinds of diabetes drugs on the market, the choice can be difficult and confusing (even for doctors). The list is available here; click on the “medication basics” tab.

This article is based on a Consumer Reports Best Buy Drugs report, written by me and other CR staffers, with input and advice from CR’s medical consultants and 3 external physician reviewers. The full report has background and other information and advice on diabetes and its treatment.

The Best Buy Drug diabetes report was, in turn, based on a review of the scientific evidence on the effectiveness, safety and adverse effects of diabetes drugs conducted by the Johns Hopkins Evidence-Based Practice Center. That review — involving some 200 studies — was sponsored by the federal Agency for Healthcare Research and Quality (AHRQ). The advice herein, however, is solely attributable to Consumer Reports Best Buy Drugs and not to Johns Hopkins, AHRQ or the US Department of Health and Human Services.

This article doesn’t evaluate insulin since it’s rarely used as an initial or ongoing treatment for people with type 2 diabetes.

Why Diabetes Is So Bad

  • Diabetes more than doubles the risk of developing and dying prematurely of heart disease and other problems.
  • Diabetes significantly raises the risk of stroke; nerve, kidney and eye damage; blindness; impotence; decreased circulation in the legs and feet; and susceptibility to infections that can lead to amputations of toes, feet or part of a leg.
  • Diabetes is the seventh leading cause of death in the United States and a leading cause of disability.
  • In the early stages of diabetes, most people don’t experience symptoms. Yet, the damage to organs occurs even in the absence of symptoms. That’s why it’s critical for people to get their blood sugar checked periodically. Also, symptoms can be mild and intermittent for years, also delaying diagnosis. These include fatigue, blurred vision, frequent urination, numbness or tingling in hands or feet, weight loss and increased thirst and hunger.

The Good News

Proper treatment can keep people with diabetes healthy. People with diabetes who receive good and consistent care can live a normal life.

The aim of treatment, with both lifestyle changes and medications, is to lower your blood sugar (as represented by your hemoglobin A1c level) and keep it low, reduce symptoms, and reduce the risk of diabetes complications.

Managing diabetes is complex, but studies are now quite clear: Lifestyle changes matter and even small changes — such as losing 10 to 15 pounds or exercising just 20 to 30 minutes several days a week — can help. Both yield solid benefits, and enable some people with diabetes to stop taking their medicines.

The 8 Types of Diabetes Meds

The 8 types of diabetes medicines work in quite different ways. But all lower blood sugar, help improve the body’s use of glucose, and decrease symptoms.

None of the 8 kinds of drugs are problem-free; all can fail to control blood sugar adequately over time in some people who take them. As a result, the different types of drugs are often used in combination, and your doctor may switch you from one type of drug to another.

About half of people with diabetes who start taking one type of medicine will need another type (or insulin) within 3 years.

Side Effects and Safety

Side effects are a serious problem with diabetes medicines. They vary from drug class to drug class and medicine to medicine.

Since many people with diabetes are trying to lose weight, the weight gain that can occur with some drugs can be especially frustrating. Here’s an overall assessment:

Common Side Effects

  • Weight gain
  • Gastrointestinal side effects (abdominal pain, nausea, vomiting, diarrhea, gassiness and bloating)
  • Edema (fluid in legs and ankles)


  • Hypoglycemia or low blood sugar (usually minor if caught in time, but can be serious or fatal if not treated; symptoms include profuse sweating, tremor, shakiness, dizziness, hunger.
  • When serious, includes mental confusion, coma, and risk of stroke or death)
  • Congestive heart failure
  • Anemia (low red blood cell count)
  • Allergic reactions
  • Urine infections
  • Yeast infections
  • Hip and non-hip fractures

Very Rare

  • Lactic acidosis (buildup of acid in the blood)
  • Macular edema (eye problems)
  • Liver disease/liver failure
  • Pancreatitis (inflamed pancreas)
  • Cancer

Overall Pros and Cons

With the very important caveat that studies do not reveal how a specific person will respond to any particular diabetes drug, our evaluation leads to the following overall conclusions:

Metformin is a good initial choice for most people.

Taking 2 diabetes drugs can have a positive additive effect on reducing HbA1c. This is a net plus for people whose blood glucose is not well controlled by taking just one drug. The downside is that taking 2 drugs poses a higher risk of side effects. Taking lower doses of each drug can reduce that risk.

Blood sugar (HbA1c) reduction is similar across all the classes of diabetes drugs, except dipeptidyl peptidase-4 inhibitors and alpha-glucosidase inhibitors, which have a somewhat smaller effect.

Diabetes drugs have differing effects on weight. It’s important to discuss this effect with your doctor. In short-term studies, the largest weight loss occurred among people taking a glucagon-like peptide 1 receptor agonist or a sodium-glucose co-transporter-2 inhibitor. Weight increased with sulfonylureas, thiazolidinediones and meglitinides.

The diabetes drugs have distinctly different “safety profiles.” Less is known about the safety of newer medications. This factor may be one of the primary drivers of your and your doctor’s decision for initial and ongoing treatment.

Minor but annoying side effects may also play a role in your and your doctor’s choice of a diabetes medicine or medicines. For example, gastrointestinal side effects — including bloating, gas, nausea, vomiting and diarrhea — are very frequent with acarbose and glucagon-like peptide-1 receptor agonists. They occur less with metformin.

What is Pre-Diabetes?

Many Americans have blood sugar levels above normal, but less than the level that warrants a diagnosis of type 2 diabetes. The most recent estimate from the CDC (Centers for Disease Control and Prevention) indicates that 34% of adults 20 and older — 84 million people — have blood glucose levels in this “pre-diabetes” or “borderline diabetes” range.

A growing body of research shows that people with pre-diabetes have both a high risk of developing diabetes, and an elevated risk of heart disease and stroke even if their blood sugar levels never rise into the full diabetes range. In one study involving 10,428 people in Australia, for example, those with pre-diabetes were found to have 2.5 times the risk of dying prematurely from heart disease over a 5-year period compared to people whose blood sugar was normal.

This has led doctors to intensify efforts to identify and treat people with pre-diabetes. But most doctors agree, and research backs them up, that dietary and lifestyle changes — with the main goal being losing weight — can be very effective at keeping pre-diabetes under control, and before any medication needs to be prescribed.

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