SURMOUNT-2: trial summary, limitations and UK relevance

Key findings

Tirzepatide (10 mg and 15 mg weekly) reduced body weight versus placebo in adults with type 2 diabetes and obesity across 72 weeks in the SURMOUNT-2 trial. The magnitude of weight reduction in the T2D cohort was reported as lower than the corresponding non-diabetic SURMOUNT-1 cohort, consistent with the broader observation that people with T2D tend to experience smaller weight reduction with incretin therapy — a subgroup consideration reproducible across the STEP and SURMOUNT programmes. HbA1c reductions were also reported, positioning tirzepatide as a therapy addressing the T2D + obesity intersection. Cardiovascular outcomes were not addressed by this trial. For precise numerical results readers should consult the primary Lancet 2023 publication.

Safety summary

GI adverse events were the most common reported tolerability signal. Hypoglycaemia events occurred but at low rates given lack of concurrent sulfonylurea/insulin use in many participants.

Limitations

• T2D-specific population — generalisability to non-diabetic obesity limited.
• 72-week duration; long-term safety, weight maintenance and cardiometabolic outcomes not established.

UK relevance

Supports use of tirzepatide for weight reduction in adults with co-existing type 2 diabetes, relevant to UK NHS prescribing pathways where T2D and obesity coexist.