Diabetologia

We conducted a systematic review and network meta-analysis to compare the efficacy and safety of s.c. administered tirzepatide vs s.c. administered semaglutide for adults of both sexes with type 2 diabetes mellitus. We searched PubMed and Cochrane up to 11 November 2023 for RCTs with an intervention duration of at least 12 weeks assessing s.c. tirzepatide at maintenance doses of 5 mg, 10 mg or 15 mg once weekly, or s.c. semaglutide at maintenance doses of 0.5 mg, 1.0 mg or 2.0 mg once weekly, in adults with type 2 diabetes, regardless of background glucose-lowering treatment. Eligible trials compared any of the specified doses of tirzepatide and semaglutide against each other, placebo or other glucose-lowering drugs. Primary outcomes were changes in HbA 1c and body weight from baseline. Secondary outcomes were achievement of HbA 1c target of &#x2264;48 mmol/mol (&#x2264;6.5%) or <53 mmol/mol (<7.0%), body weight loss of at least 10%, and safety outcomes including gastrointestinal adverse events and severe hypoglycaemia. We used version 2 of the Cochrane risk-of-bias tool (ROB 2) to assess the risk of bias, conducted frequentist random-effects network meta-analyses and evaluated confidence in effect estimates utilising the Confidence In Network Meta-Analysis (CINeMA) framework. A total of 28 trials with 23,622 participants (44.2% female) were included. Compared with placebo, tirzepatide 15 mg was the most efficacious treatment in reducing HbA 1c (mean difference -21.61 mmol/mol [-1.96%]) followed by tirzepatide 10 mg (-20.19 mmol/mol [-1.84%]), semaglutide 2.0 mg (-17.74 mmol/mol [-1.59%]), tirzepatide 5 mg (-17.60 mmol/mol [-1.60%]), semaglutide 1.0 mg (-15.25 mmol/mol [-1.39%]) and semaglutide 0.5 mg (-12.00 mmol/mol [-1.09%]). In between-drug comparisons, all tirzepatide doses were comparable with semaglutide 2.0 mg and superior to semaglutide 1.0 mg and 0.5 mg. Compared with placebo, tirzepatide was more efficacious than semaglutide for reducing body weight, with reductions ranging from 9.57 kg (tirzepatide 15 mg) to 5.27 kg (tirzepatide 5 mg). Semaglutide had a less pronounced effect, with reductions ranging from 4.97 kg (semaglutide 2.0 mg) to 2.52 kg (semaglutide 0.5 mg). In between-drug comparisons, tirzepatide 15 mg, 10 mg and 5 mg demonstrated greater efficacy than semaglutide 2.0 mg, 1.0 mg and 0.5 mg, respectively. Both drugs increased incidence of gastrointestinal adverse events compared with placebo, while neither tirzepatide nor semaglutide increased the risk of serious adverse events or severe hypoglycaemia. Our data show that s.c. tirzepatide had a more pronounced effect on HbA 1c and weight reduction compared with s.c. semaglutide in people with type 2 diabetes. Both drugs, particularly higher doses of tirzepatide, increased gastrointestinal adverse events. PROSPERO registration no. CRD42022382594.

Tirzepatide is a novel dual glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 receptor agonist (GLP-1 RA) currently under review for marketing approval. Individual trials have assessed the clinical profile of tirzepatide vs different comparators. We conducted a systematic review and meta-analysis to assess the efficacy and safety of tirzepatide for type 2 diabetes. We searched PubMed, Embase, Cochrane and ClinicalTrials.gov up until 27 October 2021 for randomised controlled trials with a duration of at least 12&#xa0;weeks that compared once-weekly tirzepatide 5, 10 or 15&#xa0;mg with placebo or other glucose-lowering drugs in adults with type 2 diabetes irrespective of their background glucose-lowering treatment. The primary outcome was change in HbA 1c from baseline. Secondary efficacy outcomes included change in body weight, proportion of individuals reaching the HbA 1c target of <53&#xa0;mmol/mol (<7.0%), &#x2264;48&#xa0;mmol/mol (&#x2264;6.5%) or <39&#xa0;mmol/mol (<5.7%), and proportion of individuals with body weight loss of at least 5%, 10% or 15%. Safety outcomes included hypoglycaemia, gastrointestinal adverse events, treatment discontinuation due to adverse events, serious adverse events, and mortality. We used version 2 of the Cochrane risk-of-bias tool for randomised trials to assess risk of bias for the primary outcome. Seven trials (6609 participants) were included. A dose-dependent superiority in lowering HbA 1c was evident with all three tirzepatide doses vs all comparators, with mean differences ranging from -17.71&#xa0;mmol/mol (-1.62%) to -22.35&#xa0;mmol/mol (-2.06%) vs placebo, -3.22&#xa0;mmol/mol (-0.29%) to -10.06&#xa0;mmol/mol (-0.92%) vs GLP-1 RAs, and -7.66&#xa0;mmol/mol (-0.70%) to -12.02&#xa0;mmol/mol (-1.09%) vs basal insulin regimens. Tirzepatide was more efficacious in reducing body weight; reductions vs GLP-1 RAs ranged from 1.68&#xa0;kg with tirzepatide 5&#xa0;mg to 7.16&#xa0;kg with tirzepatide 15&#xa0;mg. Incidence of hypoglycaemia with tirzepatide was similar vs placebo and lower vs basal insulin. Nausea was more frequent with tirzepatide vs placebo, especially with tirzepatide 15&#xa0;mg (OR 5.60 [95% CI 3.12, 10.06]), associated with higher incidence of vomiting (OR 5.50 [95% CI 2.40, 12.59]) and diarrhoea (OR 3.31 [95% CI 1.40, 7.85]). Odds of gastrointestinal events were similar between tirzepatide and GLP-1 RAs, except for diarrhoea with tirzepatide 10&#xa0;mg (OR 1.51 [95% CI 1.07, 2.15]). Tirzepatide 15&#xa0;mg led to higher discontinuation rate of study medication due to adverse events regardless of comparator, while all tirzepatide doses were safe in terms of serious adverse events and mortality. A dose-dependent superiority on glycaemic efficacy and body weight reduction was evident with tirzepatide vs placebo, GLP-1 RAs and basal insulin. Tirzepatide did not increase the odds of hypoglycaemia but was associated with increased incidence of gastrointestinal adverse events. Study limitations include presence of statistical heterogeneity in the meta-analyses for change in HbA 1c and body weight, assessment of risk of bias solely for the primary outcome, and generalisation of findings mainly to individuals who are overweight or obese and already on metformin-based background therapy. PROSPERO registration no. CRD42021283449.