Acarbose is an oral diabetes drug that slows the digestion of starch and sugar in the gut. It belongs to the alpha-glucosidase inhibitor class and is approved in the US as an add-on to diet and exercise for adults with type 2 diabetes. Bayer’s brand, Precose, was approved in 1995 and is now listed by the FDA as discontinued, but generic acarbose tablets are still marketed (Drugs@FDA, NDA 020482).
Acarbose has a second audience in longevity circles. In the National Institute on Aging’s Interventions Testing Program (ITP), acarbose added to the diet extended the median lifespan of male mice by up to 22% (Harrison et al., Aging Cell 2014). These are mouse results. No trial has tested whether acarbose extends lifespan or healthspan in people, and the large human trials measured diabetes and heart outcomes instead.
This page summarizes what the FDA label, the major clinical trials and the ITP mouse studies report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Alpha-glucosidase inhibitor; oral antihyperglycemic |
| Brands / approval | Precose (Bayer, NDA 020482, approved September 6, 1995; now discontinued); generic acarbose tablets |
| Route and strengths | Oral tablets, 25 mg, 50 mg and 100 mg |
| Labeled adult dose | Start 25 mg three times daily with the first bite of each main meal; maximum 50 mg three times daily if 60 kg or under, 100 mg three times daily if over 60 kg |
| Absorption | Under 2% of an oral dose is absorbed as active drug; it acts inside the gut |
| Half-life (label) | Plasma elimination half-life of acarbose activity about 2 h |
| Hypoglycemia on its own | Not expected (label); risk rises when combined with a sulfonylurea or insulin |
| US status | Prescription drug; not a controlled substance |
| WADA status | Not named on the 2026 Prohibited List (WADA 2026 Prohibited List) |
What it is
Acarbose is a complex oligosaccharide (a short chain of sugar-like units) made by fermentation of the microorganism Actinoplanes utahensis. Its formula is C₂₅H₄₃NO₁₈ and its molecular weight is 645.6 (acarbose tablets label).
The FDA approved Bayer’s Precose on September 6, 1995 as a new molecular entity. Drugs@FDA now lists all three Precose strengths as discontinued and notes a Federal Register determination that the product was not withdrawn for safety or effectiveness reasons (Drugs@FDA). That determination was published in January 2021 (Federal Register, 86 FR 1516). Under that determination, FDA will not start procedures to withdraw generic (ANDA) approvals that refer to Precose and can continue to approve new ones. DailyMed lists current generic acarbose labels from several manufacturers.
How it works
Most dietary starch and table sugar must be broken down into single sugars before the gut can absorb them. Acarbose blocks the enzymes that do this (acarbose tablets label):
- Pancreatic alpha-amylase, which cuts starch into shorter chains inside the small intestine.
- Intestinal alpha-glucosidases, enzymes on the gut lining that split those shorter chains and sugars such as sucrose into glucose and other simple sugars.
The inhibition is competitive and reversible. Carbohydrate is digested more slowly and further down the gut, so blood glucose rises less after a meal. Unlike sulfonylureas, acarbose does not increase insulin secretion. It does not block lactase, so the label does not expect it to cause lactose intolerance.
Two practical consequences follow from this mechanism:
- Acarbose only acts on carbohydrate eaten around the time of the dose, which is why the label ties each dose to the start of a main meal.
- Undigested carbohydrate reaches the colon, where bacteria ferment it. That fermentation produces the gas and diarrhea that dominate the side-effect profile.
Pharmacokinetics
Acarbose is designed to stay in the gut. The label calls its low systemic absorption “therapeutically desired” (acarbose tablets label).
| Parameter | Label value |
|---|---|
| Absorbed as active drug | Under 2% of an oral dose (study in 6 healthy men) |
| Total drug-related radioactivity absorbed | ≈35%, mostly as metabolites made by gut bacteria and digestive enzymes |
| Peak of active drug in plasma | ≈1 h |
| Metabolism | Only within the gut; at least 13 metabolites found in urine |
| Elimination half-life | ≈2 h; no accumulation with three-times-daily dosing |
| Severe kidney impairment (creatinine clearance under 25 mL/min/1.73 m²) | ≈5 times higher peak levels and 6 times higher AUC (total exposure) |
| Older adults | AUC and peak ≈1.5 times higher than in young volunteers (not statistically significant) |
Because acarbose is not handled by liver enzymes in the usual way, it has few pharmacokinetic interactions. The exceptions noted on the label are digoxin and a small delay in metformin absorption (see Interactions).
Approved medical use
Acarbose is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes. It can be used alone or added to a sulfonylurea, insulin or metformin (acarbose tablets label). It is not approved for preventing diabetes, for weight loss or for any aging-related use.
Labeled dosing:
| Step | Labeled dose |
|---|---|
| Start | 25 mg three times daily, with the first bite of each main meal (or 25 mg once daily, then increased in frequency, to limit GI effects) |
| Titration | Adjust every 4–8 weeks based on 1-hour post-meal glucose or HbA1c and tolerance |
| Maintenance | 50–100 mg three times daily |
| Maximum, body weight 60 kg or under | 50 mg three times daily |
| Maximum, body weight over 60 kg | 100 mg three times daily |
The weight-based cap exists because people with low body weight appear to be at higher risk of liver enzyme elevations.
What the research shows
Glucose lowering in type 2 diabetes
In six pooled fixed-dose, placebo-controlled monotherapy studies (769 acarbose-treated patients), acarbose lowered HbA1c (a measure of average blood glucose over about 3 months) at every dose tested (acarbose tablets label):
| Dose | n | Placebo-subtracted HbA1c change |
|---|---|---|
| 25 mg three times daily | 110 | −0.44% |
| 50 mg three times daily | 131 | −0.77% |
| 100 mg three times daily | 244 | −0.74% |
| 200 mg three times daily | 231 | −0.86% |
| 300 mg three times daily | 53 | −1.00% |
There were no statistically significant differences among doses from 50 to 300 mg three times daily. Doses above 100 mg three times daily are not approved.
The label also reports four US placebo-controlled add-on trials:
| Background therapy | n | HbA1c vs placebo | 1-hour post-meal glucose vs placebo |
|---|---|---|---|
| Diet only | 109 | −0.78% | −74.4 mg/dL |
| Maximum sulfonylurea | 137 | −0.54% | −33.5 mg/dL |
| Maximum metformin | 147 | −0.65% | −34.3 mg/dL |
| Insulin | 145 | −0.69% | −36.0 mg/dL |
A Cochrane meta-analysis of 41 studies found that acarbose lowered glycated hemoglobin by 0.77% versus placebo, with no added benefit above 50 mg three times daily but more side effects. It found no evidence of an effect on mortality or morbidity and no effect on blood lipids. BMI fell by 0.17 kg/m² (95% CI 0.08–0.26) (van de Laar et al., Diabetes Care 2005).
STOP-NIDDM: delaying type 2 diabetes
STOP-NIDDM randomized 1,429 people with impaired glucose tolerance (prediabetes detected on an oral glucose tolerance test) to acarbose 100 mg three times daily or placebo (Chiasson et al., Lancet 2002):
| Outcome | Acarbose | Placebo |
|---|---|---|
| Developed diabetes | 221 (32%) | 285 (42%) |
| Relative hazard | 0.75 (95% CI 0.63–0.90) | — |
| Stopped treatment early | 211 of 682 (31%) | 130 of 686 (19%) |
Acarbose also increased reversion to normal glucose tolerance. Three months of placebo after the study ended was associated with more conversion to diabetes, suggesting the effect depends on continued treatment. Flatulence and diarrhea were the most frequent side effects.
A follow-up report from the same trial (mean follow-up 3.3 years) found fewer cardiovascular events with acarbose: hazard ratio 0.51 (95% CI 0.28–0.95), a 2.5% absolute risk reduction. New hypertension was also less frequent: HR 0.66 (95% CI 0.49–0.89) (Chiasson et al., JAMA 2003). These were secondary outcomes based on a small number of events, and the ACE trial below did not confirm a heart benefit.
ACE: cardiovascular outcomes
The Acarbose Cardiovascular Evaluation (ACE) trial was a much larger randomized, double-blind, placebo-controlled trial in 6,522 Chinese patients with coronary heart disease and impaired glucose tolerance. Patients took acarbose 50 mg three times daily or placebo on top of standard heart treatment, with a median follow-up of 5.0 years (Holman et al., Lancet Diabetes Endocrinol 2017).
| Outcome | Acarbose (n = 3,272) | Placebo (n = 3,250) | Result |
|---|---|---|---|
| Five-point major cardiovascular composite | 470 (14%) | 479 (15%) | HR 0.98 (95% CI 0.86–1.11), p = 0.73 |
| New diabetes | 436 (13%) | 513 (16%) | Rate ratio 0.82 (95% CI 0.71–0.94), p = 0.005 |
| GI events leading to stopping or dose change | 215 of 3,263 (7%) | 150 of 3,241 (5%) | p = 0.0007 |
Acarbose did not reduce heart attacks, strokes, cardiovascular death or death from any cause. It did reduce new diabetes. The current label states that no clinical studies have established conclusive evidence of macrovascular (large blood vessel) risk reduction with acarbose.
A 2018 Cochrane review pooled the prevention trials. Acarbose reduced new type 2 diabetes versus placebo (16.7% vs 20.3%; RR 0.82, 95% CI 0.75–0.89; moderate-certainty evidence) but did not change all-cause mortality (RR 0.98, 95% CI 0.82–1.18) or cardiovascular mortality (RR 0.88, 95% CI 0.71–1.10). The authors found no firm evidence of a cardiovascular benefit (Moelands et al., Cochrane 2018).
Longevity: the NIA Interventions Testing Program (mouse data)
The ITP tests candidate anti-aging drugs in genetically diverse mice (UM-HET3) at three sites in parallel and publishes all results. Acarbose has extended lifespan in three separate ITP studies. All results below are from mice.
| ITP study | Diet dose and start age | Males | Females |
|---|---|---|---|
| Harrison et al., Aging Cell 2014 | 1,000 ppm from 4 months | Median lifespan +22%; 90th-percentile lifespan +11% | Median +5%; 90th percentile +9% |
| Strong et al., Aging Cell 2016 | 1,000 ppm from 16 months | Median +6%; maximal +12% | Median +2% (not significant, p = 0.07); maximal +6% |
| Harrison et al., Aging Cell 2019 | 400, 1,000 or 2,500 ppm from 8 months | Median +11%, +17% and +16%; 90th percentile +8% to +11% at each dose | Median +4% to +5% at the two higher doses; 90th percentile +3% only at 1,000 ppm |
Key points from these papers:
- Strong sex difference. The benefit was consistently larger in males. It was not explained by weight loss, which was greater in treated females.
- Starting earlier worked better. Starting at 16 months still extended male median lifespan, but by less than starting at 4 months.
- Some of the 2014 gain came from fewer early deaths. Excluding males that died before 600 days reduced the median gain from 22% to 13%, although the effect stayed statistically significant.
- Other findings in mice. In the 2019 study, acarbose at 1,000 ppm reduced lung tumors in males and liver degeneration in both sexes, and improved rotarod (balance and coordination) performance in aging females.
The ITP investigators have proposed that the benefit comes from blunting post-meal glucose peaks; this has not been proven. A separate ITP study found that canagliflozin, an SGLT2 inhibitor that lowers glucose through the kidneys, also extended median male lifespan (by 14%) but not female lifespan. The authors noted the parallel with acarbose (Miller et al., JCI Insight 2020); see the SGLT2 inhibitors page. In a mouse model of intestinal polyps (Apc+/Min mice), acarbose also improved median survival (Dodds et al., Aging Cell 2020).
For context, the 2016 ITP paper found that metformin alone (0.1% of the diet) did not significantly extend mouse lifespan, while metformin combined with rapamycin did (Strong et al., Aging Cell 2016).
Human aging studies
Human data on acarbose and aging are very limited. Two small trials are registered on ClinicalTrials.gov:
- A single-arm pilot study in 8 non-diabetic adults aged 70–95, with change in the gut microbiome as the outcome (NCT02865499).
- A placebo-controlled crossover study of muscle and fat gene expression in adults aged 60 and over, which enrolled 28 participants and was terminated early for lack of funding (NCT02953093).
Neither measured lifespan, frailty or disease outcomes. The large human outcome trials (STOP-NIDDM, ACE and the Cochrane pooled data) found no reduction in all-cause mortality.
Side effects and risks
Gastrointestinal effects
GI symptoms are the most common reaction and follow directly from the mechanism. In US placebo-controlled trials (acarbose tablets label):
| Symptom | Acarbose 50–300 mg three times daily (n = 1,255) | Placebo (n = 999) |
|---|---|---|
| Flatulence | 74% | 29% |
| Diarrhea | 31% | 12% |
| Abdominal pain | 19% | 9% |
In a one-year diary study, abdominal pain and diarrhea tended to return to pretreatment levels and flatulence eased over time. The label notes that side effects get worse if the prescribed diet is not followed. GI effects also drive dropouts: 31% of acarbose patients vs 19% on placebo stopped early in STOP-NIDDM.
A rare but serious postmarketing report is pneumatosis cystoides intestinalis (gas cysts in the bowel wall). Complications can include bowel obstruction, bleeding and perforation. The label says to stop acarbose and image the abdomen if it is suspected.
Liver enzymes
In US studies of up to 12 months that included doses up to 300 mg three times daily, transaminase (ALT/AST) elevations occurred more often on acarbose:
| Elevation | Acarbose | Placebo |
|---|---|---|
| Above the upper limit of normal | 14% | 7% |
| Over 1.8 times the upper limit | 6% | 2% |
| Over 3 times the upper limit | 3% | 1% |
These rises were dose related, asymptomatic, reversible and more common in women. At doses up to the approved maximum of 100 mg three times daily, elevations were similar to placebo. Postmarketing reports include 62 cases of transaminases over 500 IU/L (29 with jaundice) in about 3 million patient-years, and rare fatal fulminant hepatitis with an unclear relationship to acarbose. The label recommends checking transaminases every 3 months during the first year.
Hypoglycemia
Acarbose alone should not cause low blood sugar. Added to a sulfonylurea or insulin, it can increase the risk. Because acarbose blocks sucrose breakdown, the label says mild to moderate hypoglycemia should be treated with glucose (dextrose), not table sugar.
Who should not use it
The label lists these contraindications:
- known hypersensitivity to acarbose;
- diabetic ketoacidosis or cirrhosis;
- inflammatory bowel disease, colonic ulceration, partial intestinal obstruction, or a predisposition to obstruction;
- chronic intestinal diseases with marked disorders of digestion or absorption, or conditions that may worsen with increased intestinal gas.
Use is not recommended with significant kidney dysfunction (serum creatinine over 2.0 mg/dL), because it has not been studied. Safety in pregnancy and in children has not been established, and the label says it should not be given to nursing mothers.
Interactions
- Digoxin: acarbose may lower digoxin levels (mean peak level down 26%), which may require dose adjustment.
- Metformin: total metformin absorption is unchanged, but peak level falls by about 20%; the label calls the interaction of little if any clinical significance.
- Sulfonylureas and insulin: additive glucose lowering and a higher risk of hypoglycemia.
- Intestinal adsorbents and digestive enzymes: charcoal, and enzyme products containing amylase or pancreatin, may reduce the effect of acarbose.
- Drugs that raise glucose (thiazides, corticosteroids, thyroid products, estrogens, oral contraceptives and others) may cause loss of glucose control.
Lab testing
The 1,5-anhydroglucitol (1,5-AG) assay is unreliable in people taking acarbose. The label advises using other methods, such as HbA1c, to monitor glucose control.
Key takeaways
- A gut-acting carbohydrate blocker. Acarbose inhibits the enzymes that break down starch and sucrose, so less than 2% of a dose reaches the blood as active drug and post-meal glucose rises less.
- Brand gone, generics remain. Precose is listed as discontinued at FDA, not for safety or effectiveness reasons; generic acarbose tablets are still on the market for type 2 diabetes.
- Modest glucose effect. In label trials HbA1c fell by about 0.4–1.0% versus placebo, and a Cochrane review found no extra benefit above 50 mg three times daily.
- Fewer new diabetes cases, no proven heart benefit. STOP-NIDDM and ACE both showed less progression to diabetes, but the large ACE trial found no reduction in cardiovascular events or deaths.
- Lifespan data are from mice. In the NIA ITP, acarbose extended male mouse median lifespan by 6–22% depending on start age and dose, with much smaller effects in females. No human study has tested lifespan or aging outcomes.
- Gas and diarrhea are the main cost. Flatulence affected 74% of patients in US trials, and GI effects are the main reason people stop the drug.
Sources
- Food and Drug Administration. Drugs@FDA: NDA 020482, Precose (acarbose) tablets, Bayer HealthCare. FDA.
- Strides Pharma Science Limited. Acarbose tablets prescribing information, revised 08/2025. DailyMed.
- Food and Drug Administration. Determination that ARALEN (chloroquine phosphate) oral tablets, 500 milligrams, and other drug products were not withdrawn from sale for reasons of safety or effectiveness. Federal Register. January 8, 2021;86:1516 (FR Doc 2021-00118). Federal Register.
- van de Laar FA, Lucassen PL, Akkermans RP, et al. Alpha-glucosidase inhibitors for patients with type 2 diabetes: results from a Cochrane systematic review and meta-analysis. Diabetes Care. 2005;28(1):154–163. PubMed.
- Chiasson JL, Josse RG, Gomis R, et al. Acarbose for prevention of type 2 diabetes mellitus: the STOP-NIDDM randomised trial. Lancet. 2002;359(9323):2072–2077. PubMed.
- Chiasson JL, Josse RG, Gomis R, et al. Acarbose treatment and the risk of cardiovascular disease and hypertension in patients with impaired glucose tolerance: the STOP-NIDDM trial. JAMA. 2003;290(4):486–494. PubMed.
- Holman RR, Coleman RL, Chan JCN, et al. Effects of acarbose on cardiovascular and diabetes outcomes in patients with coronary heart disease and impaired glucose tolerance (ACE): a randomised, double-blind, placebo-controlled trial. Lancet Diabetes Endocrinol. 2017;5(11):877–886. PubMed.
- Moelands SV, Lucassen PL, Akkermans RP, et al. Alpha-glucosidase inhibitors for prevention or delay of type 2 diabetes mellitus and its associated complications in people at increased risk of developing type 2 diabetes mellitus. Cochrane Database Syst Rev. 2018;12(12):CD005061. PubMed.
- Harrison DE, Strong R, Allison DB, et al. Acarbose, 17-α-estradiol, and nordihydroguaiaretic acid extend mouse lifespan preferentially in males. Aging Cell. 2014;13(2):273–282. PubMed; PMC.
- Strong R, Miller RA, Antebi A, et al. Longer lifespan in male mice treated with a weakly estrogenic agonist, an antioxidant, an α-glucosidase inhibitor or a Nrf2-inducer. Aging Cell. 2016;15(5):872–884. PubMed; PMC.
- Harrison DE, Strong R, Alavez S, et al. Acarbose improves health and lifespan in aging HET3 mice. Aging Cell. 2019;18(2):e12898. PubMed; PMC.
- Miller RA, Harrison DE, Allison DB, et al. Canagliflozin extends life span in genetically heterogeneous male but not female mice. JCI Insight. 2020;5(21):e140019. PubMed.
- Dodds SG, Parihar M, Javors M, et al. Acarbose improved survival for Apc(+/Min) mice. Aging Cell. 2020;19(2):e13088. PubMed.
- University of Texas Health Science Center at San Antonio. Acarbose as a safe effective modulator of aging deficits in geriatric subjects. ClinicalTrials.gov NCT02865499. ClinicalTrials.gov.
- Montefiore Medical Center. Study of changes in muscle and fat gene transcription with acarbose treatment: a crossover study. ClinicalTrials.gov NCT02953093. ClinicalTrials.gov.
- World Anti-Doping Agency. The 2026 Prohibited List. WADA 2026 Prohibited List.