The most widely prescribed diabetes medications fall into several distinct classes, each lowering blood sugar through a different mechanism. Metformin remains the standard first-line treatment for type 2 diabetes, but the list of effective options has grown significantly. Here are ten of the most commonly prescribed diabetes medications, what they do, and what to expect from each.
1. Metformin
Metformin is the default starting medication for type 2 diabetes in nearly every treatment guideline worldwide. It works by reducing the amount of sugar your liver releases into your bloodstream and by helping your cells respond better to insulin. On average, it lowers A1c by about 1.5 percentage points.
Most people start at 500 mg once daily with dinner and gradually increase over several weeks to a maximum of 2,000 mg per day, split between breakfast and dinner. The slow ramp-up exists for a reason: stomach upset, nausea, and diarrhea are common early on but tend to fade as your body adjusts. Metformin doesn’t cause low blood sugar on its own and is weight-neutral or slightly weight-friendly, which is partly why it’s held the top spot for decades.
2. Semaglutide (Ozempic, Rybelsus)
Semaglutide belongs to the GLP-1 receptor agonist class, which mimics a gut hormone that triggers insulin release after meals and slows stomach emptying. Ozempic is the injectable version given once weekly; Rybelsus is a daily oral tablet. Both produce significant A1c reductions, often in the range of 1.5 to 2 percentage points, and most people lose a noticeable amount of weight on them.
Nausea is the most common side effect, especially in the first few weeks. Doses are increased gradually to minimize this. GLP-1 drugs have also shown cardiovascular benefits in clinical trials, making them a preferred second-line choice for people with heart disease or at high risk for it.
3. Empagliflozin (Jardiance)
Empagliflozin is an SGLT2 inhibitor, a class that works by blocking your kidneys from reabsorbing sugar back into your blood. The excess sugar leaves through urine instead, which also means you lose some calories and water along with it. Most people experience modest weight loss and lower blood pressure as side effects of this mechanism.
What sets Jardiance apart is its track record for protecting the heart and kidneys. In large clinical trials, it reduced the combined risk of cardiovascular death and heart failure hospitalization by about 21% in people with reduced heart function, and by about 21% in those with preserved heart function as well. Urinary tract infections and yeast infections are the main downsides, since sugar in the urinary tract creates a more hospitable environment for bacteria and fungi.
4. Dapagliflozin (Farxiga)
Farxiga is another SGLT2 inhibitor with a similar mechanism to Jardiance. It has particularly strong evidence for kidney protection: in one major trial, it reduced the risk of serious kidney disease progression by 39%. It also cut the combined risk of cardiovascular death or heart failure hospitalization by 26% in people with heart failure.
The side effect profile mirrors Jardiance closely. Genital yeast infections and urinary tract infections are the most frequent complaints. Dehydration can also be a concern since the drug increases urination, so staying well-hydrated matters. Both SGLT2 inhibitors are now prescribed not just for blood sugar control but specifically to protect the heart and kidneys, even in some people who don’t have diabetes at all.
5. Sitagliptin (Januvia)
Sitagliptin is a DPP-4 inhibitor. This class works by blocking an enzyme that normally breaks down incretin hormones, the same gut hormones that GLP-1 drugs mimic. The result is a modest, meal-triggered boost in insulin production. DPP-4 inhibitors are less potent than GLP-1 drugs but come with fewer side effects and are taken as a simple once-daily pill.
Sitagliptin is considered weight-neutral and carries a low risk of hypoglycemia. Side effects in clinical studies were mild, mostly limited to occasional gastrointestinal discomfort and upper respiratory symptoms. Long-term cardiovascular safety studies have shown sitagliptin to be neutral on heart outcomes, neither helping nor harming.
6. Saxagliptin (Onglyza)
Onglyza works through the same DPP-4 mechanism as Januvia and offers similar blood sugar lowering. The important distinction is a safety signal: in its large cardiovascular outcomes trial, saxagliptin was associated with a significant increase in hospitalizations for heart failure. This doesn’t mean it causes heart failure outright, but it has made many prescribers more cautious about using it in people who already have heart problems or are at elevated risk for them.
If you’re on Onglyza and have no heart failure risk factors, there’s no reason to panic. But if you have a history of heart failure or notice unusual swelling in your legs or shortness of breath, that’s worth bringing up with your prescriber.
7. Glipizide
Glipizide is a sulfonylurea, one of the oldest classes of diabetes drugs still in regular use. Sulfonylureas stimulate your pancreas to release more insulin regardless of your blood sugar level, which makes them effective but also explains their main risk: hypoglycemia. They lower A1c by roughly 1 to 2 percentage points and are very inexpensive, which keeps them popular despite newer alternatives.
Glipizide has a shorter duration of action compared to other sulfonylureas, which gives it a slightly lower hypoglycemia risk. Weight gain of a few pounds is typical. These drugs work best when your pancreas still has meaningful insulin-producing capacity, so they tend to become less effective over time as type 2 diabetes progresses.
8. Glimepiride
Glimepiride is another sulfonylurea, often chosen because it can be dosed once daily. It delivers A1c reductions of 1 to 2 percentage points, similar to glipizide. However, glimepiride has the longest half-life of the commonly used sulfonylureas, which may contribute to a somewhat higher rate of hypoglycemia.
Like all sulfonylureas, glimepiride is a poor choice for people with significantly reduced kidney function. Some of its byproducts are cleared through the kidneys, and impaired clearance can lead to drug accumulation, amplifying the blood sugar lowering effect and raising hypoglycemia risk. If you’re on glimepiride and your kidney function declines over time, your prescriber will likely switch you to something else.
9. Pioglitazone (Actos)
Pioglitazone belongs to the thiazolidinedione class, which works by making fat and muscle cells more sensitive to insulin. It’s effective for blood sugar control and has some evidence for reducing fatty liver disease, a condition that commonly coexists with type 2 diabetes.
The trade-offs are significant, though. Fluid retention is a well-known side effect, and it can worsen or trigger heart failure in susceptible people. Rapid weight gain or excessive swelling in the hands, ankles, or feet are warning signs that need immediate medical attention. Pioglitazone also increases the risk of bone fractures in women. These concerns have pushed it lower on most prescribing hierarchies, but it remains useful for specific patients who can’t tolerate other options.
10. Insulin Glargine (Lantus)
Insulin glargine is the most widely prescribed basal (long-acting) insulin. It’s used in type 2 diabetes when oral medications and other injectables can no longer keep blood sugar in range, and it’s also a mainstay for type 1 diabetes. After injection, it takes about 3 to 4 hours to start working, has no pronounced peak, and provides a steady background level of insulin for approximately 24 hours. That peakless profile is what makes it safer than older insulin formulations, which could cause unpredictable drops in blood sugar.
Two other basal insulins are worth knowing about. Detemir (Levemir) starts working faster, within 1 to 2 hours, but its duration ranges from 14 to 24 hours, so some people need twice-daily injections. Degludec (Tresiba) also kicks in within 1 to 2 hours but lasts over 40 hours, which allows more flexibility in injection timing and tends to produce even fewer low blood sugar episodes.
Combination Medications
Many of the drugs above are also available as fixed-dose combinations that merge two medications into a single pill. Janumet combines sitagliptin with metformin. Glyxambi pairs empagliflozin with the DPP-4 inhibitor linagliptin. These combination pills don’t offer anything pharmacologically new, but they reduce the number of pills you take each day, which can make it easier to stick with treatment.
The downside is less flexibility. If you need to adjust the dose of one component, you may have to switch back to individual pills. Cost can also vary, since a brand-name combination pill is sometimes more expensive than taking the two generic components separately. Your pharmacist can often tell you which approach is cheaper with your specific insurance.