Question 1

Does SURMOUNT-CN apply to non-Chinese Asian populations such as Japanese, Korean, or South Asian patients?

Accepted Answer

SURMOUNT-CN enrolled only Chinese adults at 29 centers in China, so any extrapolation to other Asian populations is indirect. The closest companion datasets are the SURPASS-AP-Combo trial (tirzepatide vs insulin glargine in the Asia-Pacific region, Gao 2023 Nat Med, PMID 37231074), which included Japanese and Korean participants in a diabetes setting, and STEP 7 (semaglutide 2.4 mg in a predominantly East Asian population, Mu 2024 Lancet Diabetes Endocrinol, PMID 38330988). South Asian populations were not directly studied in any of these. The WHO Expert Consultation (PMID 14726171) recommends the lower BMI ≥27.5 or ≥28 threshold for most Asian populations, so the eligibility criteria of SURMOUNT-CN are broadly transferable, but population-specific safety and pharmacokinetic data outside East Asia remain limited.

Question 2

Why does China use BMI ≥28 to define obesity instead of the Western ≥30 threshold?

Accepted Answer

Chinese adults develop type 2 diabetes, hypertension, and cardiovascular disease at lower body-mass index values than European-ancestry adults at the same level of body fat. The Cooperative Meta-Analysis Group of the Working Group on Obesity in China (Zhou 2002, PMID 12046553) and the WHO Expert Consultation on Asian BMI cutoffs (Lancet 2004, PMID 14726171) recommended a BMI of 24 kg/m² as overweight and 28 kg/m² as obesity for Chinese adults, reflecting their higher visceral-fat proportion and earlier onset of cardiometabolic risk at any given BMI. SURMOUNT-CN's eligibility criteria of BMI ≥28, or ≥24 with a weight-related comorbidity, were drawn directly from those Chinese clinical guidelines.

Question 3

Was weight loss higher or lower in SURMOUNT-CN than in SURMOUNT-1?

Accepted Answer

Percent weight loss at the matched 15-mg dose was lower in SURMOUNT-CN (−17.5% at week 52) than in SURMOUNT-1 (−20.9% at week 72), but the comparison is not apples-to-apples. SURMOUNT-1 ran 20 weeks longer, so participants had more time to accumulate weight loss after dose escalation; baseline body weight in SURMOUNT-CN was 91.8 kg versus 104.8 kg in SURMOUNT-1, so absolute kilograms lost were smaller (−15.9 kg vs −23.6 kg); and the Chinese cohort was younger (mean age 36 vs 45). When time and baseline weight are accounted for, the relative trajectory is broadly similar, and SURMOUNT-CN's placebo arm lost only 2.3% over 52 weeks, very close to the 3.1% placebo loss at 72 weeks in SURMOUNT-1, suggesting comparable adherence to lifestyle counseling across populations.

Question 4

Did Chinese participants in SURMOUNT-CN show different side-effect rates than Western tirzepatide trials?

Accepted Answer

The pattern of gastrointestinal adverse events in SURMOUNT-CN matched the multinational tirzepatide program closely: nausea (32.4% at 15 mg), diarrhea (22.5%), and decreased appetite (19.7%) were the leading events, all clustered during the dose-escalation phase and mostly mild-to-moderate. Aggregate discontinuation for adverse events was under 5% on tirzepatide, similar to SURMOUNT-1 (4.3-7.1% across the three doses). Serious-adverse-event rates were 4-6% on tirzepatide vs 4.3% on placebo with no signal in any organ system. The trial did not report a population-specific safety concern that would change the labeling for Chinese patients beyond what is already in the multinational product labels.

Question 5

Is tirzepatide approved in China for weight management?

Accepted Answer

Yes. China's National Medical Products Administration (NMPA) approved tirzepatide for chronic weight management in adults with obesity (BMI ≥28) or overweight (BMI ≥24) with at least one weight-related comorbidity in 2024, with SURMOUNT-CN serving as the principal pivotal Chinese trial alongside the multinational SURMOUNT program. The product is marketed in China by Eli Lilly under the brand name Mounjaro for the diabetes indication and is available in 10 mg and 15 mg doses for the weight-management indication consistent with the SURMOUNT-CN protocol. Pricing, distribution, and reimbursement are handled separately by provincial health insurance schemes.

Question 6

Were any Chinese-population-specific subgroup analyses prespecified in SURMOUNT-CN?

Accepted Answer

SURMOUNT-CN reported the standard ITT analyses by treatment arm but, because the trial enrolled only Chinese adults at 29 Chinese centers, there was no ethnicity stratification in the primary analysis. Sex-based and BMI-stratified subgroup analyses were performed and showed consistent treatment effects across female and male participants and across BMI bands above and below 32 kg/m². The trial excluded type 2 diabetes, so glycemic-status subgroups (normoglycemic vs prediabetic at baseline) were the principal stratification, and tirzepatide produced a numerically larger absolute weight reduction in participants with prediabetes, mirroring the pattern observed in SURMOUNT-1's extended-follow-up cohort.

Endpoint	Treatment	Comparator	Difference
≥10% body weight reduction at week 52 Roughly three-quarters of 15-mg participants crossed the 10% threshold typically associated with improvements in obstructive sleep apnea, NAFLD, and glycemic control.	15 mg: 77.5%; 10 mg: 64.4%	Placebo: 9.5%	P<0.001 for both tirzepatide doses vs placebo
≥15% body weight reduction at week 52 Threshold approaching the lower end of weight loss reported with sleeve gastrectomy at one year — achieved without surgery in a majority of 15-mg participants.	15 mg: 60.6%; 10 mg: 42.5%	Placebo: 2.4%	P<0.001 for both tirzepatide doses vs placebo
≥20% body weight reduction at week 52 No placebo participant reached 20% loss; nearly half of 15-mg participants did.	15 mg: 43.7%; 10 mg: 22.6%	Placebo: 0%	P<0.001 for both tirzepatide doses vs placebo
Absolute body-weight change at week 52 (kg) Absolute kilogram loss is smaller than SURMOUNT-1 (−23.6 kg at 15 mg) because Chinese baseline weight was lower (91.8 vs 104.8 kg), but percent loss is comparable.	15 mg: −15.9 kg; 10 mg: −12.6 kg	Placebo: −2.1 kg	Treatment difference at 15 mg: −13.8 kg vs placebo
Waist-circumference change at week 52 (cm) Visceral-fat surrogate; magnitude similar to multinational tirzepatide trials.	15 mg: −13.1 cm; 10 mg: −10.7 cm	Placebo: −2.7 cm	Treatment difference at 15 mg: −10.4 cm vs placebo
Systolic blood pressure change at week 52 (mmHg) Magnitude comparable to a low-dose antihypertensive added to standard care.	15 mg: −6.5 mmHg; 10 mg: −5.4 mmHg	Placebo: −0.2 mmHg	Treatment difference at 15 mg: −6.3 mmHg vs placebo
HbA1c change at week 52 (%) Participants had no diabetes at entry; HbA1c shifted within the normoglycemic / prediabetic range, similar in magnitude to STEP-1 and SURMOUNT-1 in non-diabetic populations.	15 mg: −0.46%; 10 mg: −0.45%	Placebo: −0.05%	Treatment difference at 15 mg: −0.41 percentage points vs placebo
Fasting serum insulin change at week 52 (% from baseline) Reflects a sharp drop in hyperinsulinemia, consistent with restored insulin sensitivity in the Chinese population.	15 mg: −45.5%; 10 mg: −41.0%	Placebo: −5.5%	Treatment difference at 15 mg: −40.0 percentage points vs placebo
Triglycerides change at week 52 (% from baseline)	15 mg: −26.3%; 10 mg: −22.7%	Placebo: −3.4%	Treatment difference at 15 mg: −22.9 percentage points vs placebo
Non-HDL cholesterol change at week 52 (% from baseline)	15 mg: −5.9%; 10 mg: −6.6%	Placebo: −0.5%	—

Event	Treatment rate	Comparator rate
Nausea (most-common AE) Most cases mild-to-moderate; clustered during dose-escalation. Aggregate GI rates were broadly similar to multinational tirzepatide trials.	15 mg: 32.4%; 10 mg: 22.9%	Placebo: 13.0%
Diarrhea Second-most-common GI AE; usually transient.	15 mg: 22.5%; 10 mg: 21.4%	Placebo: 14.5%
Decreased appetite Reported as an AE per study convention, though it is part of the mechanism rather than a complication.	15 mg: 19.7%; 10 mg: 17.1%	Placebo: 2.9%
Constipation	15 mg: 14.1%; 10 mg: 14.3%	Placebo: 4.3%
Vomiting	15 mg: 12.7%; 10 mg: 8.6%	Placebo: 2.9%
Abdominal distension	15 mg: 8.5%; 10 mg: 8.6%	Placebo: 2.9%
Discontinuation due to adverse event Few events led to treatment discontinuation per the JAMA report; full intention-to-treat completion was 95.7%.	Tirzepatide arms pooled: <5%	Placebo: comparable low rate
Serious adverse events (any) No imbalance vs placebo; no deaths reported during the 52-week treatment period.	15 mg: 5.6%; 10 mg: 4.3%	Placebo: 4.3%

SURMOUNT-CN deep dive: tirzepatide in Chinese adults with obesity (Zhao 2024 JAMA)

Primary endpoint

Secondary endpoints

Adverse events

Clinical significance

Frequently Asked Questions

References

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