Tirzepatide vs Semaglutide: What the Trials Mean for The Bahamas

The question Bahamian physicians are being asked

Demand for GLP-1 drugs in The Bahamas is rising. Dr Kristine Parker-Curling, described by The Tribune as the only full-time endocrinologist working in the country, said in September 2026 that demand for Ozempic and Mounjaro is "significantly and steadily increasing"¹. The context is a heavy disease burden: The Tribune reported a 2025 Pan American Health Organization study ranking The Bahamas first for adult obesity in the Americas, with more than 70% of adults overweight or obese and about 40% obese¹. Our News cited PAHO data putting overweight and obesity at nearly 76% of Bahamian adults², and a sports medicine physician wrote in 2025 that WHO figures named The Bahamas as the country with the highest obesity rate in the Americas³.

Patients increasingly arrive asking which drug is "better": semaglutide (Ozempic, Wegovy) or tirzepatide (Mounjaro, Zepbound). The trials give a clearer answer on weight than on outcomes.

SURMOUNT-5: the head-to-head obesity trial

SURMOUNT-5, published in the New England Journal of Medicine in 2025, was the first randomized trial comparing the two drugs directly in obesity⁵. It enrolled 751 adults with obesity but without type 2 diabetes and gave each the maximum tolerated dose of tirzepatide or semaglutide once weekly for 72 weeks. Weight fell by a least-squares mean of 20.2% with tirzepatide and 13.7% with semaglutide; waist circumference fell 18.4 cm and 13.0 cm. Tirzepatide-treated participants were more likely to reach every weight-loss threshold tested, from 10% to 25%⁵. The trial was open-label and funded by Eli Lilly, the maker of tirzepatide.

The result fits the placebo-controlled programmes. In STEP 1, semaglutide plus lifestyle intervention produced a mean weight change of −14.9% at 68 weeks against −2.4% with placebo⁷. In SURMOUNT-1, tirzepatide produced mean reductions of 15.0% to 20.9% at 72 weeks, depending on dose, against 3.1% with placebo⁸. Gastrointestinal effects, mostly mild to moderate and concentrated in dose escalation, were the most common adverse events with both drugs⁵⁷⁸.

In type 2 diabetes: SURPASS-2

For patients with type 2 diabetes the comparison came earlier. SURPASS-2 randomized 1,879 patients to one of three tirzepatide doses or semaglutide for 40 weeks⁶. All tirzepatide doses were noninferior and superior to semaglutide on HbA1c, with estimated differences of −0.15 to −0.45 percentage points, and weight fell more with tirzepatide, by 1.9 kg to 5.5 kg relative to semaglutide⁶. Serious adverse events were reported in 5% to 7% of tirzepatide patients and 3% of semaglutide patients⁶.

What the trials do not settle: outcomes

Weight is not the only end point that matters to a Bahamian practice full of cardiovascular and metabolic disease. Semaglutide has a placebo-controlled outcome trial in people with obesity and established cardiovascular disease but no diabetes: in SELECT, 17,604 patients were followed for a mean of 39.8 months and the primary composite of cardiovascular death, nonfatal myocardial infarction or nonfatal stroke occurred in 6.5% with semaglutide and 8.0% with placebo (hazard ratio 0.80)⁹.

Tirzepatide's first cardiovascular outcome trial used an active comparator. SURPASS-CVOT randomized 13,299 patients with type 2 diabetes and atherosclerotic cardiovascular disease to tirzepatide or dulaglutide, a GLP-1 drug with proven cardiovascular benefit. The primary end point occurred in 12.2% and 13.1% (hazard ratio 0.92; 95.3% CI 0.83 to 1.01): noninferior, but not statistically superior¹⁰. Greater weight loss with tirzepatide has not yet been shown to translate into fewer heart attacks or strokes than semaglutide in a direct comparison.

Stopping treatment, and the cost problem

Both drugs work only while they are taken. In the STEP 1 extension, people who stopped semaglutide regained two-thirds of their prior weight loss within a year, and cardiometabolic improvements moved back toward baseline¹². In SURMOUNT-4, participants switched from tirzepatide to placebo regained 14.0% of body weight over 52 weeks, while those who continued lost a further 5.5%¹¹.

That is why access matters in The Bahamas. GLP-1 drugs are not covered by the national prescription drug plan; the health minister says the government intends to extend National Health Insurance coverage to them for obesity and type 2 diabetes, but with monthly costs of $250 to more than $1,500, The Tribune reports a growing market for their "unregulated acquisition"¹. The World Health Organization's December 2025 guideline makes only a conditional recommendation for semaglutide, tirzepatide and liraglutide in adult obesity, citing limited long-term data, cost, health-system preparedness and equity, and projects that these drugs will reach fewer than 10% of those who could benefit by 2030⁴. PAHO's February 2026 alert asks prescribers to keep use within approved indications with individual assessment and continuous monitoring¹³, and WHO has warned of falsified Ozempic batches in circulation¹⁴.