What Is A1C Reduction in GLP-1 Studies? Verified 2026 Trial Data
Published:
·Last verified: May 19, 2026.What is A1C reduction in GLP-1 studies? It’s the average drop in A1C — a blood test that tracks your average blood sugar over about three months — that researchers measured when they tested a GLP-1 medication in a clinical trial. Across the FDA-label trial tables reviewed for this page, GLP-1 and GLP-1-related medications lowered A1C by roughly 0.7 to 2.4 percentage points in treatment-regimen data, with some published efficacy-estimand analyses of tirzepatide reaching about 2.6 points.
The largest mean A1C reductions in published trials belong to tirzepatide (Mounjaro), a dual GIP/GLP-1 medication. The largest reductions from a single-receptor GLP-1 come from semaglutide (Ozempic, Wegovy, Rybelsus). The newest GLP-1 — orforglipron, sold as Foundayo — was FDA-approved on April 1, 2026 for chronic weight management; its type 2 diabetes data from the ACHIEVE trial program is strong but the diabetes indication has not yet been approved.
What we actually verified.
Where the FDA prescribing label includes a trial table, we use those values (typically the treatment-regimen estimand). Where it does not, we use the primary peer-reviewed publication and label the estimand. A small number of rows for the newest 2026 readouts come from manufacturer topline announcements pending full publication — those are clearly marked. We do not present unverified figures. Last verified May 19, 2026.
What A1C is, in plain English
The American Diabetes Association uses these thresholds:
| A1C level | Category | Notes |
|---|---|---|
| Below 5.7% | Normal | No diagnosis |
| 5.7% – 6.4% | Prediabetes | Lifestyle intervention recommended |
| 6.5% or higher | Diabetes | Confirmed with repeat testing |
| Below 7.0% | Typical T2D target | Individualized by age, hypoglycemia risk, other conditions |
Source: American Diabetes Association Standards of Care 2026. Targets are individualized; older adults or those with serious comorbidities may have higher targets (7.5%–8.0%). Younger people without complications may aim for below 6.5%.
Percentage points vs percent — the trap that confuses everyone
The most important thing to understand before reading any trial number:
When a GLP-1 study says “A1C reduced by 1.5%,” it almost always means a 1.5 percentage-point drop — going from 8.5% to 7.0% — not a 1.5% relative improvement.
What trials mean
8.5% → 7.0%
1.5 percentage-point drop
What it is NOT
17.6% relative drop
(1.5 ÷ 8.5) × 100 — nobody uses this in diabetes care
Clinical significance
Uncontrolled → ADA target
A 1.5-point drop from 8.5% is the difference that matters
From this point on, when this page says “A1C reduction of X%,” we mean percentage points. Every number in the table below is read the same way.
Quick study-language decoder (read this first)
Half the confusion about GLP-1 trial results comes from one thing: the way the numbers are written.
| You see this in a study | What it actually means | Concrete example |
|---|---|---|
| "A1C dropped by 1.5%" | A 1.5 percentage-point drop — not a 1.5% relative improvement | 8.5% → 7.0% |
| "Change from baseline" | The drop from the group's starting A1C | Baseline 8.1%, change −1.6%, ending A1C 6.5% |
| "Placebo-adjusted reduction" | How much more the drug lowered A1C than placebo did | Drug −1.6%, placebo −0.1%, adjusted difference −1.5% |
| "Reached A1C <7%" | The share of trial participants who got below 7% | 73% reached <7% |
| "Efficacy estimand" | Effect if you stay on the drug as prescribed — no stopping, no rescue meds | Usually the larger number |
| "Treatment-regimen estimand" | Effect counting everyone, including people who quit or added meds | Usually the smaller number — and what most FDA labels show |
Which numbers are FDA-label verified vs topline-only?
Trust the FDA-label numbers first. They have been audited, vetted, and published in the official prescribing information. Peer-reviewed publications come next. Company topline announcements are used only for the newest 2026 ACHIEVE-program readouts and labeled clearly.
🟢 FDA label / DailyMed table
Verified by regulators; used wherever available. The gold standard.
🟡 Peer-reviewed primary publication
Used when the label does not include the trial (older trials, head-to-head trials, newest approvals).
🟠 Company topline announcement
Used only for the newest ACHIEVE program rows not yet in a US label; clearly labeled as topline.
The verified GLP-1 A1C reduction table (2026 edition)
A1C reduction data from current FDA prescribing labels and primary phase 3 trial publications, normalized into one table. Each row shows the drug, trial, dose, starting A1C, comparator, A1C reduction, and participants reaching A1C below 7%.
Semaglutide (Ozempic, Wegovy, Rybelsus, Wegovy HD)
| Trial | Dose | Baseline A1C | Comparator | A1C reduction (drug) | Comparator reduction | Reached A1C <7% | Tier |
|---|---|---|---|---|---|---|---|
| SUSTAIN 2 (add-on metformin/TZD) | 0.5 mg weekly | 8.0% | Sitagliptin 100 mg | −1.3% | −0.7% | 66% | 🟢 |
| SUSTAIN 2 (add-on metformin/TZD) | 1.0 mg weekly | 8.0% | Sitagliptin 100 mg | −1.5% | −0.7% | 73% | 🟢 |
| SUSTAIN 5 (add-on basal insulin) | 0.5 mg weekly | 8.4% | Placebo | −1.3% | −0.2% | 56% | 🟢 |
| SUSTAIN 5 (add-on basal insulin) | 1.0 mg weekly | 8.3% | Placebo | −1.7% | −0.2% | 73% | 🟢 |
| SUSTAIN 7 (head-to-head) | 0.5 mg weekly | 8.3% | Dulaglutide 0.75 mg | −1.5% | −1.1% | 68% | 🟡 |
| SUSTAIN 7 (head-to-head) | 1.0 mg weekly | 8.2% | Dulaglutide 1.5 mg | −1.8% | −1.4% | 79% | 🟡 |
| SUSTAIN 8 (vs SGLT-2) | 1.0 mg weekly | 8.3% | Canagliflozin 300 mg | −1.5% | −1.0% | — | 🟡 |
| SUSTAIN FORTE | 2.0 mg weekly | 8.9% | Sema 1.0 mg | −2.2% | −1.9% | — | 🟡 |
| PIONEER (oral / Rybelsus, pooled) | 14 mg daily | 7.7–8.3% | Various | −1.0% to −1.3% | Varies | 55%–77% | 🟡 |
| STEP 2 (2.4 mg in T2D + obesity) | 2.4 mg weekly | 8.1% | Placebo | −1.6% | −0.4% | 68% reached ≤6.5% | 🟡 |
| STEP UP T2D (7.2 mg in T2D + obesity) | 7.2 mg weekly | 8.0% | Placebo | −1.6% | −0.2% | — | 🟡 |
Tirzepatide (Mounjaro, Zepbound) — dual GIP/GLP-1, not a single-receptor GLP-1
Tirzepatide activates both the GIP receptor and the GLP-1 receptor, which is why it works differently from pure GLP-1s. Included here because people compare it side-by-side with GLP-1s.
| Trial | Dose | Baseline A1C | Comparator | A1C reduction (drug) | Comparator reduction | Reached A1C <7% | Tier |
|---|---|---|---|---|---|---|---|
| SURPASS-1 (monotherapy) | 5 mg weekly | 8.0% | Placebo | −1.8% | −0.1% | 82% | 🟢 |
| SURPASS-1 (monotherapy) | 10 mg weekly | 7.9% | Placebo | −1.7% | −0.1% | 85% | 🟢 |
| SURPASS-1 (monotherapy) | 15 mg weekly | 7.9% | Placebo | −1.7% | −0.1% | 78% | 🟢 |
| SURPASS-2 (vs semaglutide, efficacy estimand) | 5 mg weekly | 8.3% | Sema 1 mg | −2.01% | −1.86% | 82% | 🟡 |
| SURPASS-2 (vs semaglutide, efficacy estimand) | 10 mg weekly | 8.3% | Sema 1 mg | −2.24% | −1.86% | 86% | 🟡 |
| SURPASS-2 (vs semaglutide, efficacy estimand) | 15 mg weekly | 8.3% | Sema 1 mg | −2.30% | −1.86% | 86% | 🟡 |
| SURPASS-3 (vs insulin degludec) | 15 mg weekly | 8.2% | Insulin degludec | −2.1% | −1.3% | 83% | 🟢 |
| SURPASS-4 (vs insulin glargine, high CV risk) | 5 mg weekly | 8.5% | Insulin glargine | −2.1% | −1.4% | 75% | 🟢 |
| SURPASS-4 (vs insulin glargine, high CV risk) | 10 mg weekly | 8.5% | Insulin glargine | −2.3% | −1.4% | 83% | 🟢 |
| SURPASS-4 (vs insulin glargine, high CV risk) | 15 mg weekly | 8.5% | Insulin glargine | −2.4% | −1.4% | 85% | 🟢 |
| SURPASS-5 (add-on basal insulin) | 5 mg weekly | 8.3% | Placebo | −2.1% | −0.9% | 87% | 🟢 |
| SURPASS-5 (add-on basal insulin) | 10 mg weekly | 8.4% | Placebo | −2.4% | −0.9% | 90% | 🟢 |
| SURPASS-5 (add-on basal insulin) | 15 mg weekly | 8.2% | Placebo | −2.3% | −0.9% | 85% | 🟢 |
Orforglipron (Foundayo) — newest 2026 approval
Important context on orforglipron data:
Orforglipron (Foundayo) was FDA-approved April 1, 2026 for chronic weight management only — not type 2 diabetes glycemic control. The doses in the table below (3 mg, 12 mg, 36 mg) are investigational ACHIEVE-program doses, not the labeled Foundayo titration schedule. When ACHIEVE results are eventually translated into a US T2D label, doses may map differently. Lilly has indicated plans to seek a T2D indication; that approval has not happened.
| Trial | Dose (investigational) | Baseline A1C | Comparator | A1C reduction (drug) | Comparator reduction | Tier |
|---|---|---|---|---|---|---|
| ACHIEVE-1 (monotherapy, efficacy estimand) | 3 mg | 8.0% | Placebo | −1.3% | −0.1% | 🟠 |
| ACHIEVE-1 (monotherapy, efficacy estimand) | 12 mg | 8.0% | Placebo | −1.6% | −0.1% | 🟠 |
| ACHIEVE-1 (monotherapy, efficacy estimand) | 36 mg | 8.0% | Placebo | −1.5% | −0.1% | 🟠 |
| ACHIEVE-2 (vs SGLT-2, efficacy estimand) | 3 mg | 8.1% | Dapagliflozin | −1.3% | −0.8% | 🟠 |
| ACHIEVE-2 (vs SGLT-2, efficacy estimand) | 12 mg | 8.1% | Dapagliflozin | −1.7% | −0.8% | 🟠 |
| ACHIEVE-2 (vs SGLT-2, efficacy estimand) | 36 mg | 8.1% | Dapagliflozin | −1.7% | −0.8% | 🟠 |
| ACHIEVE-3 (vs oral semaglutide, efficacy estimand) | 12 mg | 8.3% | Oral sema 7 mg | −1.9% | −1.1% | 🟡 |
| ACHIEVE-3 (vs oral semaglutide, efficacy estimand) | 36 mg | 8.3% | Oral sema 14 mg | −2.2% | −1.4% | 🟡 |
| ACHIEVE-5 (add-on insulin glargine, efficacy estimand) | 3 mg | 8.5% | Placebo | −1.5% | −0.8% | 🟠 |
| ACHIEVE-5 (add-on insulin glargine, efficacy estimand) | 12 mg | 8.5% | Placebo | −2.1% | −0.8% | 🟠 |
| ACHIEVE-5 (add-on insulin glargine, efficacy estimand) | 36 mg | 8.5% | Placebo | −1.9% | −0.8% | 🟠 |
Dulaglutide (Trulicity), liraglutide (Victoza), older agents
| Drug | Trial(s) | Dose | Baseline A1C | Comparator | A1C reduction | Tier |
|---|---|---|---|---|---|---|
| Dulaglutide (Trulicity) | AWARD monotherapy | 0.75 mg weekly | 7.6% | Metformin (−0.6%) | −0.7% | 🟢 |
| Dulaglutide (Trulicity) | AWARD monotherapy | 1.5 mg weekly | 7.6% | Metformin (−0.6%) | −0.8% | 🟢 |
| Dulaglutide (Trulicity) | AWARD-11 (higher doses) | 1.5 mg weekly | 8.6% | — | −1.5% | 🟢 |
| Dulaglutide (Trulicity) | AWARD-11 | 3.0 mg weekly | 8.6% | — | −1.6% | 🟢 |
| Dulaglutide (Trulicity) | AWARD-11 | 4.5 mg weekly | 8.6% | — | −1.8% | 🟢 |
| Liraglutide (Victoza) | LEAD-3 monotherapy | 1.2 mg daily | 8.2% | Glimepiride (−0.5%) | −0.8% | 🟢 |
| Liraglutide (Victoza) | LEAD-3 monotherapy | 1.8 mg daily | 8.2% | Glimepiride (−0.5%) | −1.1% | 🟢 |
| Liraglutide (Victoza) | LEAD-6 vs exenatide | 1.8 mg daily | 8.2% | Exenatide 10 mcg BID (−0.79%) | −1.12% | 🟡 |
| Exenatide IR (Byetta) | AMIGO trials | 10 mcg twice daily | ~8.3% | Placebo / various | −0.78% to −1.0% | 🟡 |
The class picture — BMJ 2024 network meta-analysis (76 RCTs, 39,246 participants)
Orforglipron is not yet in this meta-analysis because the ACHIEVE program results are too new, but ACHIEVE-3 places it ahead of oral semaglutide and roughly competitive with mid-range injectable performance. A 2025 Scientific Reports Bayesian network meta-analysis (64 trials, 25,572 participants) corroborated the tirzepatide > semaglutide > liraglutide ranking.
Which GLP-1 lowers A1C the most?
A warning before you make a decision based on this:
“Biggest A1C drop” is one consideration, not the only one. The right GLP-1 for you is not automatically the one with the biggest number. It is the one that hits your A1C target without unacceptable side effects, fits your insurance or budget, and matches what your body and life can sustain.
Cardiovascular outcomes
Ozempic has FDA-approved MACE reduction (SUSTAIN 6) and kidney protection (FLOW). Mounjaro does not have these labeled indications.
Route matters
Foundayo (orforglipron) does not require fasting. Rybelsus does — empty stomach, very limited water. Injections vs. pills change who can use them.
Side effects
Tirzepatide and high-dose semaglutide can cause more nausea than older drugs, especially during dose escalation.
Oral vs. injectable
If you cannot or will not inject, oral options change the conversation entirely.
Not sure which GLP-1 fits your situation?
Our free 60-second matching quiz asks about your insurance, state, budget, and health history, then shows you FDA-approved paths that may fit. No payment, no commitment.
Take the Free 60-Second Matching Quiz →What does a 1-point A1C drop actually mean in blood sugar?
A1C change → estimated average glucose change
| A1C change | Avg glucose change |
|---|---|
| −0.5 points | roughly −14 mg/dL |
| −1.0 points | roughly −29 mg/dL |
| −1.5 points | roughly −43 mg/dL |
| −2.0 points | roughly −57 mg/dL |
| −2.5 points | roughly −71 mg/dL |
A1C → estimated average glucose (eAG)
| Your A1C | Estimated avg glucose |
|---|---|
| 5.0% | 97 mg/dL |
| 6.0% | 126 mg/dL |
| 7.0% (ADA target) | 154 mg/dL |
| 8.0% | 183 mg/dL |
| 9.0% | 212 mg/dL |
| 10.0% | 240 mg/dL |
| 11.0% | 269 mg/dL |
| 12.0% | 298 mg/dL |
So if your A1C drops from 8.5% to 7.0% on a GLP-1, your average blood sugar fell from roughly 197 mg/dL to 154 mg/dL — a 43-point average drop, every minute of every day, for months. That is why even a “modest” 1.5-point A1C reduction has a clinical impact your body actually feels.
One caveat: eAG is an estimate based on a formula. Your real day-to-day glucose, especially on a CGM, may show a slightly different number because the relationship between A1C and average glucose varies a little person to person. Source: Nathan DM, et al. Diabetes Care. 2008;31:1473–1478.
How long until A1C drops on a GLP-1?
Week 1–2
Fasting glucose and post-meal spikes often start dropping. You may feel a difference in energy and hunger before any A1C number changes.
Week 4–8
A1C starts to improve, but the test still mostly reflects pre-treatment glucose. An A1C check this early underestimates the real effect.
Week 12–16
Most of the A1C drop is now visible on labs. This is the first realistic checkpoint.
Week 26 and beyond
Effect approaches steady state. Most trials report their primary A1C endpoint here or later.
Baseline-adjusted ranges observed in trial subgroups
| Your starting A1C | Range on Ozempic 1.0 mg | Range on Mounjaro 10–15 mg |
|---|---|---|
| 7.0%–7.5% | −0.7% to −1.2% | −1.0% to −1.6% |
| 7.5%–8.5% | −1.2% to −1.8% | −1.9% to −2.3% |
| 8.5%–9.5% | −1.7% to −2.5% | −2.3% to −2.8% |
| Above 9.5% | −2.2% to −2.8% | −2.5% to −3.0% |
Methodology note: ranges are editorial estimates built from subgroup analyses in SUSTAIN 1–5 (Canadian Journal of Diabetes 2017) and SURPASS pooled subgroup data. Not validated prediction intervals; do not use to choose or change medication. Orforglipron/Foundayo omitted because the ACHIEVE investigational doses do not map cleanly to labeled Foundayo doses, and the diabetes label is not yet approved.
Near target (A1C 7.0–7.2%)
Absolute drops are smaller — there is just less room to go.
At 9.5%+
Your A1C may drop more than the trial mean because you have more glucose to lower.
Not everyone reaches <7%
A meaningful minority of trial participants did not reach A1C below 7% even on active therapy.
Why do GLP-1 A1C numbers differ so much between studies?
Baseline A1C
Higher starting A1C = larger absolute drop. SUSTAIN 1–5 subgroup data show semaglutide reductions ranging from 0.7% in patients starting below 7.5% to 2.8% in patients starting above 9%. Same drug, same dose, different starting point.
Dose
Higher doses generally produce larger A1C reductions across a trial program, but the dose-response is not perfectly monotonic. SURPASS-1 reports tirzepatide 5 mg at −1.8% and 10/15 mg both at −1.7%. Dose, baseline A1C, comparator, and estimand all need to be read together.
Trial duration
A 30-week trial captures the full A1C effect. A 12-week trial does not. Do not compare those headlines directly.
Comparator
A drug vs. placebo shows the largest drug effect. A drug vs. an active medication (sitagliptin, insulin, another GLP-1) shows a smaller comparator-adjusted advantage because the comparator is also lowering A1C.
Background medications
SURPASS-1 was monotherapy. SURPASS-2 was add-on to metformin. SURPASS-3 was add-on to insulin. Same drug at the same dose can give different A1C drops depending on what else patients were taking.
Estimand choice
The efficacy estimand answers "what happens if you stay on the drug as planned?" The treatment-regimen estimand answers "what happens to everyone, even people who quit?" The efficacy estimand is usually bigger. FDA labels typically show treatment-regimen numbers.
Patient population
SURPASS-4 enrolled people with established cardiovascular disease, who tend to have had diabetes longer and respond a bit differently than newly diagnosed patients in SURPASS-1.
Can A1C go too low on a GLP-1?
GLP-1 alone
Hypoglycemia is uncommon. Most people will not see A1C go too low.
GLP-1 + insulin or sulfonylurea
Your other medications often need to be reduced as your A1C drops. Your clinician — not you — should manage that.
A1C in the low 5s
Not automatically a problem, but worth a conversation. Are you having lows? Is your CGM showing time-below-range?
Symptoms of hypoglycemia (in roughly the order they appear)
If any of these are happening regularly, that is a “call your clinician” situation, not a “wait it out” situation.
Does a lower A1C mean diabetes is cured or in remission?
“My A1C went from 9.2 to 6.0 on Ozempic — am I cured?”
The medication is doing its job. If you stop the medication, A1C typically drifts back up over several months because the underlying disease — insulin resistance and beta-cell dysfunction — is still there.
“Will my insurance stop covering my GLP-1 now that my A1C is normal?”
Coverage rules are plan-specific. If your coverage is denied or reviewed after your A1C improves, keep documentation of your original diagnosis, pre-treatment A1C, medication start date, your current response, and your clinician's rationale for continuing therapy.
“Should I stop the drug now that my numbers are good?”
Discuss it with your clinician. Stopping a GLP-1 is occasionally appropriate, often not, and the answer depends on your full picture.
What happens to A1C if you stop the GLP-1?
After stopping a GLP-1, blood sugar control often worsens over the following months. The exact pattern depends on how much weight you regain, what other diabetes medications you stay on, your underlying disease severity, and your follow-up plan. Some people see modest A1C creep; others return close to pre-treatment levels within a year. There is no reliable way to predict which group you will be in.
Practical implication: if you are considering stopping a GLP-1 because of cost, side effects, or because “your numbers are good,” do not do it abruptly without a plan.
A1C reduction is not the only thing that matters
| Factor | Key data point |
|---|---|
| Cardiovascular outcomes | Semaglutide has labeled MACE reduction in adults with established CV disease (SUSTAIN 6). Liraglutide has similar data from LEADER. Tirzepatide does not yet have a labeled CV outcomes indication. |
| Kidney protection | Semaglutide has labeled kidney protection in adults with T2D and CKD, based on the FLOW trial. No other GLP-1 currently has a kidney indication. |
| Weight loss | Tirzepatide: up to 22.5% in SURMOUNT. Semaglutide 2.4 mg (Wegovy): 14.9–16.9%. Wegovy HD 7.2 mg: ~20.7%. Orforglipron 36 mg: ~7.9% at 40 weeks. Older agents produce less. |
| Side effects | GI side effects (nausea, vomiting, diarrhea, constipation) are most common across the class, worst during dose escalation. Tirzepatide and high-dose semaglutide tend to have higher rates than older agents. |
| Route | Weekly injections: Ozempic, Mounjaro, Trulicity, Bydureon. Daily injections: Victoza. Daily pills: Rybelsus (for diabetes), Wegovy oral, Foundayo (weight management). |
| Cost | Highly variable by drug, insurance plan, pharmacy channel, and cash-pay program. See our GLP-1 cost guide for current price checks. |
A1C reduction is one input. The right GLP-1 for you balances multiple factors against your specific health situation.
Why trial averages tend to be bigger than real-world results
Adherence
Trial participants take their medication on schedule under research-team supervision. In the real world, missed doses, late refills, and travel interrupt dosing.
Time on therapy
Trials measure A1C at 30 or 40 or 52 weeks — full-dose, steady state. In the real world, people titrate slower, stop and restart, or sit at sub-therapeutic doses for cost reasons.
Side effects
Trial dropouts due to side effects are recorded; in real life people quietly stop refilling without telling anyone.
Patient mix
Trials exclude many patients (recent medication changes, severe comorbidities, heart failure, pancreatitis). Real-world patients are often more medically complex.
This is not a reason to be cynical about trial numbers — they are the best evidence we have. But it is a reason to set realistic personal expectations.
How we built this page
We pulled A1C reduction data from current FDA prescribing labels (via DailyMed) wherever the trial appears there — that is the green tier. Where the label does not include a trial, we used the peer-reviewed primary publication — the yellow tier. For the newest 2026 ACHIEVE-program rows, we used Eli Lilly's company topline announcements pending full publication — the orange tier, clearly labeled. Every A1C reduction figure is tied to the specific phase 3 trial, the dose tested, the baseline A1C of trial participants, the comparator, and the estimand. We did not include any rows we could not verify.
Sources used
- ·FDA prescribing information via DailyMed for Ozempic, Mounjaro, Trulicity, Victoza, and Foundayo
- ·Peer-reviewed primary publications: NEJM (SUSTAIN 6, SURPASS-2), Lancet (STEP 2, SURPASS-3, SURPASS-4), Lancet Diabetes & Endocrinology (SUSTAIN 7, SUSTAIN 8, STEP UP T2D, ACHIEVE-3), JAMA (SURPASS-5)
- ·Network meta-analyses: BMJ 2024 (Karagiannis et al., 76 RCTs, 39,246 participants); Scientific Reports / Nature 2025 (64 RCTs, 25,572 participants)
- ·ADA Standards of Care 2026 for A1C targets; ADA consensus on remission criteria
- ·NIDDK for the basic mechanism of A1C
What we excluded
- ·Manufacturer claims not backed by a published trial table or DailyMed label
- ·Real-world anecdotes from forums and Reddit
- ·Studies in populations outside this page's scope (type 1 diabetes, pediatric, pregnancy)
- ·Any row that could not be sourced to one of the three tiers
Refresh schedule: We re-verify the table every 90 days and any time an FDA label is updated. Next scheduled review: August 2026.
Disclosure: The RX Index may earn affiliate commissions from some provider links elsewhere on this site. This page's trial table is based on FDA labels and published studies, not affiliate relationships. No affiliate program influenced any number, ranking, or clinical interpretation here.
Questions to ask your clinician
Bring this list to your next appointment. Most of these are not Google-able for you specifically — only your clinician has the full picture.
“Based on my baseline A1C, what reduction is realistic on this GLP-1?”
“Which trial population is closest to my situation?”
“When should we recheck A1C? (Most clinicians wait at least 3 months after starting or changing dose.)”
“Should we adjust my insulin or sulfonylurea as my A1C drops?”
“What side effects should trigger a call rather than waiting?”
“If my A1C improves below the diabetes threshold, how do we document it for insurance?”
“What is the plan if I do not reach my A1C target on this dose?”
“Is there a reason this specific GLP-1 fits my situation better than another one?”
FAQ — A1C reduction in GLP-1 studies
Is A1C reduction reported in percent or percentage points?
Percentage points. A drop from 8.5% to 7.0% is a 1.5 percentage-point reduction, not a 1.5% relative improvement. Every number on this page and in published GLP-1 trials uses percentage points.
How much do GLP-1 drugs lower A1C on average?
Across phase 3 trials in adults with type 2 diabetes, 0.7 to 2.4 percentage points in FDA-label treatment-regimen tables, with published efficacy-estimand analyses reaching about 2.6 points. The 2024 BMJ network meta-analysis ranked tirzepatide highest at minus 2.10% vs placebo; semaglutide around minus 1.5%; liraglutide around minus 1.2%; older agents in the minus 0.7% to minus 1.0% range.
Which GLP-1 lowers A1C the most?
Tirzepatide (Mounjaro) produced the largest A1C reductions in the SURPASS program, up to minus 2.4 percentage points in FDA-label tables and up to minus 2.30 points in published efficacy-estimand analyses. Tirzepatide is technically a dual GIP/GLP-1 medication, not a pure GLP-1, but it is compared alongside GLP-1s and is the current category leader for A1C drop.
How much does Ozempic lower A1C?
In the SUSTAIN program, Ozempic (semaglutide injection) lowered A1C by minus 1.3 to minus 1.8 percentage points at the standard 0.5 mg and 1.0 mg doses in FDA-label tables, depending on the trial setting and baseline. The 2.0 mg dose (SUSTAIN FORTE) reached minus 2.2 percentage points in efficacy-estimand analyses.
How much does Mounjaro lower A1C?
In FDA-label SURPASS tables, Mounjaro (tirzepatide) lowered A1C by minus 1.7 to minus 2.4 percentage points, with the largest reductions at the 10 mg and 15 mg doses and in patients with higher baseline A1C or those starting from background basal insulin (SURPASS-5).
How much does orforglipron lower A1C?
In the ACHIEVE phase 3 program, orforglipron lowered A1C by minus 1.3 to minus 2.2 percentage points at the investigational trial doses (3, 12, 36 mg). In the only published head-to-head (ACHIEVE-3 vs oral semaglutide), the 36 mg dose produced minus 2.2% vs oral semaglutide 14 mg's minus 1.4%. Orforglipron is currently FDA-approved as Foundayo for chronic weight management, not for type 2 diabetes glycemic control.
How much does Trulicity lower A1C?
In the AWARD program, Trulicity (dulaglutide) lowered A1C by minus 0.7 to minus 1.8 percentage points depending on dose (0.75 mg, 1.5 mg, 3 mg, or 4.5 mg) and baseline A1C. The 4.5 mg dose produced the largest mean reduction at higher baselines.
How long does it take for a GLP-1 to lower A1C?
Fasting glucose often starts dropping in 1 to 2 weeks. Because A1C reflects the trailing 2 to 3 months of average glucose, the full A1C effect does not show on labs until 12 to 16 weeks. Most clinicians wait at least 3 months before judging whether a GLP-1 is working at A1C.
Can a GLP-1 cause low blood sugar?
By itself, low risk. Combined with insulin or sulfonylureas (glipizide, glimepiride, glyburide), the hypoglycemia risk is meaningfully higher and your other medications usually need to be reduced as your A1C drops. The FDA labels for the GLP-1s reviewed here carry this warning.
Does a lower A1C mean my diabetes is cured?
No. A lower A1C on a GLP-1 means the medication is working. The ADA defines remission as A1C below 6.5% sustained for at least 3 months without active glucose-lowering medication. Coming off the GLP-1 typically causes A1C to drift back up over the following months.
Will my insurance stop covering my GLP-1 if my A1C improves?
Coverage rules are plan-specific. If your plan reviews or denies coverage after your A1C improves, keep documentation of your original diagnosis, pre-treatment A1C, the date you started, your current response, and your clinician's rationale for continued therapy. Ask your insurer about its appeal or prior authorization process.
Why is my real A1C reduction smaller than the trial number?
Real-world reductions can be smaller than trial averages because of adherence gaps, slower dose escalation, dropouts due to side effects, and more medically complex patient populations. A real-world study of Ozempic 1.0 mg patients found a 1.2-point mean reduction compared to the 1.5 to 1.8 percent in SUSTAIN trials.
Should I switch GLP-1s if my A1C is not dropping enough?
Switching is a clinician decision. Reasons to discuss it include not reaching the agreed A1C target after enough time at an appropriate dose, intolerable side effects, insurance changes, or a better fit for your other health goals. Sometimes adding or adjusting another diabetes medication is more appropriate than switching GLP-1s.
Sources
- ·¹ NIDDK. The A1C Test & Diabetes. https://www.niddk.nih.gov/health-information/diagnostic-tests/a1c-test
- ·² American Diabetes Association. Diagnosis. https://diabetes.org/about-diabetes/diagnosis
- ·³ ADA Standards of Care in Diabetes 2026. Section 6: Glycemic Targets.
- ·⁴ DailyMed. Ozempic (semaglutide injection) prescribing information.
- ·⁵ Pratley RE, et al. SUSTAIN 7. Lancet Diabetes Endocrinol. 2018.
- ·⁶ Lingvay I, et al. SUSTAIN 8. Lancet Diabetes Endocrinol. 2019.
- ·⁷ Frías JP, et al. SUSTAIN FORTE. ADA 81st Scientific Sessions. 2021.
- ·⁸ Aroda VR, et al. PIONEER program review. Am J Manag Care.
- ·⁹ Davies M, et al. STEP 2. Lancet. 2021;397:971-984.
- ·¹⁰ Lingvay I, et al. STEP UP T2D. Lancet Diabetes Endocrinol. 2025;13(11):935-948.
- ·¹¹ DailyMed. Mounjaro (tirzepatide injection) prescribing information.
- ·¹² Frías JP, et al. SURPASS-2. NEJM. 2021;385:503-515.
- ·¹³ Karagiannis T, et al. BMJ. 2024. PMID: 38286487.
- ·¹⁴ DailyMed. Foundayo (orforglipron) prescribing information.
- ·¹⁵ Eli Lilly. ACHIEVE-1 topline. investor.lilly.com.
- ·¹⁶ Eli Lilly. ACHIEVE-2 and ACHIEVE-5 topline. October 15, 2025. investor.lilly.com.
- ·¹⁷ Eli Lilly. ACHIEVE-3 published in The Lancet. February 2026.
- ·¹⁸ DailyMed. Trulicity (dulaglutide injection) prescribing information.
- ·¹⁹ DailyMed. Victoza / liraglutide injection prescribing information.
- ·²⁰ Trujillo JM, et al. GLP-1 receptor agonists head-to-head. Ther Adv Endocrinol Metab. 2021.
- ·²¹ US Pharmacist. GLP-1 Receptor Agonists. https://www.uspharmacist.com.
- ·²² Efficacy and safety of GLP-1 agonists. Scientific Reports (Nature). 2025.
- ·²³ Nathan DM, et al. Translating the A1C Assay. Diabetes Care. 2008;31:1473-1478.
- ·²⁴ Lingvay I, et al. Semaglutide Reduces HbA1c Across Baseline Subgroups. Canadian J Diabetes. 2017.
- ·²⁵ DailyMed. Foundayo prescribing information — warnings on concomitant insulin and secretagogues.
- ·²⁶ ADA. International Experts Outline Diabetes Remission Criteria. diabetes.org.
- ·²⁷ Real-World HbA1c Changes — Ozempic 1.0 mg. J Health Econ Outcomes Res. 2025. https://jheor.org/article/124111
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· Last verified: May 19, 2026. Next scheduled review: August 2026.Affiliate disclosure: The RX Index earns a commission when you sign up with some of the providers mentioned on this page. It does not affect what you pay, and it never determines our rankings or which providers we cover. Read the full disclosure.