Tirzepatide roll out for obesity clearer, but questions remain

As we are faced with a rising tide of obesity, with a third of adults in England now having a BMI ≥30 kg/m² and a staggering 64% being in the overweight or obese category (NHS England, 2024), the challenges of management and workforce capacity affect us all. The causes of obesity are multifactorial and the consequences wide-ranging, particularly the increased risk of type 2 diabetes. For many years now, we have grown accustomed to the use of GLP-1 receptor agonists in the management of type 2 diabetes and have had to cope through a period of extended global shortage.

Advances in the development of incretin-based therapies, however, have seen the launch of tirzepatide (brand name Mounjaro®), a dual GIP and GLP-1 receptor agonist. Tirzepatide was licensed in 2022 to treat type 2 diabetes and in 2023 for weight management and weight loss in adults. We have, however, been waiting for guidance before rolling it out for this latter cohort. 

NHS England (2025) has now published interim commissioning guidance on the implementation of the recommendations set out in the technology appraisal on the use of tirzepatide as an option for the management of overweight and obesity (NICE, 2023). It sets out a plan for its incremental roll out across England.

Until now the use of incretin-based treatments for obesity (liraglutide and semaglutide) has been restricted for use in specialist Tier 3 weight management services, and all have been limited to a maximum two-year prescribing period.

For the use of tirzepatide, this is now set to change. Guidance has been provided for its use in the treatment of obesity in primary care, and there is no time limitation for its use. The only restriction is that at least 5% of initial weight should be lost within a 6-month period, at the highest tolerated dose, prior to consideration for continued prescribing.

Given the chronic challenges seen in specialist weight management service availability, this change is welcome relief for some. It does, however, pose questions about the capacity issues this will add to our already over-stretched primary care colleagues. 

Typically, when NICE produce a technology appraisal, there is an expectation that the roll out of the guidance will take place within in a 3-month time frame. However, given the enormity of this technology appraisal, a funding variation has been applied and a staggered roll-out programme for primary care produced. 

The funding variation for tirzepatide is two-fold. First, specialist weight management services are expected to comply with the technology appraisal for all eligible people within the standard 90-day time frame. Primary care has an extended time of 180 days and a phased approach to person eligibility. A suggested 220,000 eligible individuals should receive tirzepatide for the management of obesity over the first three years, with all people who meet the criteria having access within a 12-year time frame.

Given the estimated number of those who meet the criteria (an initial BMI ≥35 kg/m² with at least one weight-related comorbidity) is 3.4 million in England, the funding variation has produced a clear phased roll out for primary care.

In year 1, those with a BMI ≥40 kg/m² with at least four weight-related comorbidities will be eligible to receive tirzepatide from primary care. In year 2, access will be given to people with a BMI of 35–39.9 kg/m² with at least four weight-related comorbidities, and, in year 3, to those with a BMI ≥40 kg/m² with at least three weight-related comorbidities. For each of these cohorts, the BMI threshold should be reduced by 2.5 kg/m² for those from high-risk ethnic backgrounds.

Although many in primary care are very familiar and experienced at prescribing and supporting people with type 2 diabetes with incretin-based injectable therapies, the workload required to also prescribe for weight management cannot be underestimated. In regular virtual clinics with GP practices across my area, the main topic of conversation is identifying eligible cohorts of people who comply with the type 2 diabetes tirzepatide licensing and NICE guidance in light of a tsunami of people who are requesting it. When we now add to the discussion the indication for weight loss, the overwhelming sense of anxiety regarding capacity is palpable. 

The main question when it comes to the use of tirzepatide for weight loss in primary care relates to the additional “wraparound” support people receive when they attend specialist weight management services. Although mandated in the technology appraisal, the wraparound service that is expected from primary care is less clear, although there is an expectation that additional support regarding exercise and dietary advice should be provided from suitably trained professionals. The exact meaning of “suitably trained” is not explained. This ambiguity is an obvious area of concern for primary care. There is also a clear expectation for monthly face-to-face follow-up visits during the titration phase and structured medication reviews for at least the first 12 months of prescribing.

So, whilst we are all excited about the advancement in medications for the management of both type 2 diabetes and obesity, the impact on already overstretched primary care services is real and worrying. 

Links to the technology appraisal and NHS England guidance can be found in the references below. We all need to be very familiar with their contents, as I am sure that many of the questions from primary care will come to us. Currently, this will only affect England, and we are awaiting the positions from the other home nations regarding roll out.

I leave these thoughts with you and will undoubtedly return to this topic in future editorials!