Diabetes Forecast

Wait Times: How Long Until Your Med Begins Working

Photography by Mike Watson Images/Thinkstock

There are many type 2 medications, and each drug class works in the body in a different way. Here’s a quick guide to help you understand how long each drug will generally take to work:

Alpha Glucosidase Inhibitors

acarbose, miglitol

These short-acting oral medications, taken with meals, block the breakdown of complex sugars into simple sugars in the gastrointestinal (GI) tract. “Simple sugars are more easily absorbed and cause the blood sugar to ultimately go up,” Sam Ellis, PharmD, BCPS, CDE, associate professor in the Department of Clinical Pharmacy at the University of Colorado says. These drugs are minimally absorbed into the blood, so a certain blood level concentration is not necessary for them to work. You will see the effect immediately with the first dose. “You take it before a meal, and with that meal you see the effect,” says George Grunberger, MD, FACP, FACE, President of the American Association of Clinical Endocrinologists.

Bile Acid Sequestrants

cholestyramine, colesevelam, colestipol

While researchers aren’t exactly sure how these oral medications work, it’s likely that the meds block some absorption of glucose in the GI tract. “You’ll see most of the effect in the first week with these drugs,” says Ellis.

DPP-4 Inhibitors

alogliptin, linagliptin, saxagliptin, sitagliptin

These drugs work to block the enzyme responsible for the breakdown of a specific gut hormone that helps the body produce more insulin when blood glucose is high and reduces the amount of glucose produced by the liver. Take a DPP-4 inhibitor (they come in pill form) and it’ll work pretty fast—you’ll see the full effect in about a week. “It’s blocking that enzyme after the first dose a little bit, but by the time you get out to dose five, you’re blocking the majority of that enzyme,” Ellis says.

GLP-1 Receptor Agonists

albiglutide, dulaglutide, exenatide, exenatide extended release, liraglutide 

These drugs are injected, but unlike insulin they mimic a peptide in the body that lowers blood glucose and glucagon levels. (Glucagon is a peptide responsible for raising the concentration of glucose in the blood.) GLP-1 medications also reduce appetite, which can lead to weight loss. There are several formulations on the market, all of which release the medication differently. The rapid-acting, twice-a-day exenatide injection, for example, takes effect immediately. “This is like rapid-acting insulin,” says Grunberger. “When you inject at a meal, you will see the effect immediately.” The once-a-day formulation, liraglutide, is similar to basal insulin and will take 24 hours to affect blood glucose. Three once-weekly formulations also exist, but because of their dissimilar molecular structures, they take effect at different times. People typically experience full blood glucose–lowering effects after two to four weeks of dulaglutide, four to five weeks of albiglutide, and six to seven weeks of exenatide extended release. Keep in mind: If you switch from a twice-a-day or once-a-day formulation to a weekly dose, you may not see the effect of the new drug immediately. “[You] may potentially lose blood glucose control for a short period of time,” says Ellis.


nateglinide, repaglinide

These drugs, taken orally three times daily with meals, stimulate the release of insulin from the pancreas. “They get absorbed very quickly, and they get eliminated very quickly,” says Ellis. Meglitinides will start working with the first dose. Bonus: They don’t have to build up in the system before hitting their maximum blood glucose–lowering effect like some other drugs.


Metformin works in a few ways. It helps your body properly respond to its insulin, reduces glucose production in the liver, and helps block glucose absorption in your intestines. Metformin is a quick-acting oral medication—you will typically see some effect within 48 hours of starting the medication. Maximum effect will take about four to five days, but that depends on the dose. There’s a good chance you’ll start with a small metformin dose—500 milligrams once a day—and build up over a few weeks until you’re taking at least 1,500 milligrams daily. This slow start method can help you avoid side effects such as upset stomach, but it also changes how quickly you’ll see results. “Patients won’t notice a big change in their blood glucose when they start [a low dose],” says Ellis. “We really need to get at least 1,500 milligrams a day before we start to see that drug have much effect on blood sugars.”

SGLT-2 Inhibitors

canagliflozin, dapagliflozin, empagliflozin

SGLT-2 inhibitors, which are taken orally, block a transporter in the kidneys responsible for reabsorbing glucose. This causes glucose to be lost in the urine, which results in lower glucose levels in the body. As with DPP-4s, you’ll see some response from your first dose of an SGLT-2 drug, but it may take a week to see the full response. “Once you get to steady state, you could start to see some of the [side effects],” Ellis says. Those include an increased risk for genital yeast infections.


chlorpropamide, glimepiride, glipizide, glyburide, tolazamide, tolbutamide

In large part, these oral medications work very quickly because they stimulate the pancreas’ release of insulin. “You see a response starting with the first dose,” says Evan Sisson, PharmD, MHA, CDE, associate professor in the Department of Pharmacotherapy and Outcomes Science at Virginia Commonwealth University. That said, the maximum effect won’t be seen for a few more days, up to two weeks.


pioglitazone, rosiglitazone

For thiazolidinediones to work, they must enter the cells to increase a glucose transporter, a process that takes quite a while. While you may see some effect after two weeks, it could take 18 to 20 weeks before you see the maximal effect. These meds are taken orally.

Insulin Informed

Insulin is pretty straightforward in terms of how long it will take to see the effects. Formulations for different absorption rates are available and will be consistent based on which kind you use.

  • Rapid Acting Expect this to begin to work 15 to 20 minutes after injection, peak at about 90 minutes, and last two to four hours.
  • Regular or Short Acting You will start to see the effects after 30 minutes. Regular insulin peaks about two to three hours after injection and is effective for about three to six hours.
  • Intermediate Acting This reaches the bloodstream about two to four hours after injection, peaks at four to 12 hours, and is effective for 12 to 18 hours.
  • Long Acting You’ll see this start to work an hour after injection. There is no peak, and it will keep blood glucose even for 24 hours.
  • Ultra Long Acting While this type will start working after six hours, there is no peak. The effects will last for 36 hours.

For an at-a-glance look at medication start times, check out our handy chart.

Click here for more about type 2 medications and what it takes for them to work.

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