COMBINE 4 randomised 485 adults with type 2 diabetes and an HbA1c of 8.0% or more, already on oral drugs and not yet on insulin, to once-weekly IcoSema — insulin icodec combined with semaglutide in one pen — or once-daily insulin glargine U100. It was open-label and treat-to-target, run at 97 sites in nine countries over 40 weeks. Baseline HbA1c was about 9.5% in both arms.
IcoSema cut HbA1c by 3.32 percentage points against 2.44 for glargine, a difference of 0.88 points (95% CI -1.12 to -0.63). Weight moved in opposite directions: down 0.79 kg on IcoSema, up 3.81 kg on glargine, a gap of 4.61 kg. Clinically significant or severe hypoglycaemia was about half as frequent, at 0.29 versus 0.59 episodes per person-year (rate ratio 0.56, 95% CI 0.32 to 0.97). Better glucose, less weight, less hypoglycaemia and 52 injections a year instead of 365 — that combination is what makes this a practice changer rather than another trial.
IcoSema is not yet available in most markets, including India, so nothing changes in tomorrow's clinic list. What changes is the argument. When a patient on maximal oral therapy needs insulin, adding a GLP-1 receptor agonist alongside basal insulin rather than starting basal insulin alone now has a head-to-head trial behind it. Read the effect sizes knowing the trial was open-label and funded by the manufacturer. Gastrointestinal upset was the commonest adverse event.
- At insulin initiation, record weight and hypoglycaemia history before choosing between basal insulin alone and a basal plus GLP-1 combination.
- Warn patients starting any GLP-1 component about nausea, and titrate slowly rather than abandoning the drug at the first symptom.
- The titration target here was a fasting glucose of 3.9–5.0 mmol/L (70–90 mg/dL) — tighter than many clinics use; check what your own protocol actually sets.
- For a patient already gaining weight on basal insulin, treat that as a prompt to reconsider the regimen, not to add more units.
- Ask about injection burden explicitly — weekly dosing helps most the patients who are quietly missing daily doses.
The statistics, in plain English
The HbA1c difference of 0.88 percentage points has a confidence interval of -1.12 to -0.63. It sits entirely below zero, so the direction of benefit is not in doubt; only its size is. The hypoglycaemia rate ratio of 0.56 has an upper bound of 0.97 — just under 1.0, so the result is statistically significant but only barely, and a much smaller benefit than the point estimate is still compatible with the data. The weight difference of 4.61 kg (CI -5.46 to -3.75) is the most precise of the three. Because the trial was open-label, participants and investigators knew the allocation; that matters most for outcomes involving judgement, such as when to titrate, and least for HbA1c, which is a laboratory measure.
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