New guidelines emphasise tailored and careful management of incretin therapy switches in primary care

As obesity and type 2 diabetes treatments evolve, clinicians face complex challenges in switching between GLP-1 receptor agonists and dual incretin therapies, necessitating personalised and closely monitored approaches to optimise outcomes and minimise risks.

Primary care clinicians are increasingly having to manage a new kind of medication handover: patients moving between GLP-1 receptor agonists and dual incretin therapies as treatment for obesity and type 2 diabetes becomes more widespread. According to Medscape’s review, the reasons range from insurance changes and persistent gastrointestinal side effects to inadequate weight loss or glucose control. The key point, experts say, is that a switch is not a simple substitution. It calls for attention to the drug’s half-life, the patient’s previous dose, how well the first medicine was tolerated and whether blood sugar could fall too quickly.

The American Diabetes Association’s recent standards on obesity and diabetes management reinforce that approach. Their guidance puts the patient’s preferences, access to treatment and side-effect burden at the centre of decision-making, rather than treating all incretin-based drugs as interchangeable. Practical guidance published in Clinical Diabetes and expert consensus in the International Journal of Clinical Practice both describe similar principles: transitions should be planned, dose histories should be reviewed carefully and the timing of the first dose of the new drug should be aligned with the next scheduled dose of the old one. In most cases, that means no washout period is needed.

Hani Soudah, an associate professor of medicine at WashU Medicine in St. Louis, said the overlap between these once-weekly or daily medicines means clinicians generally should not leave a treatment gap. “Because these are all once-weekly or daily agents with long half-lives, there is no washout period needed for a class switch , start the new drug when the next dose of the old one would have been due,” Soudah said. He and other specialists also caution against unnecessary duplication, including continuing medicines such as DPP-4 inhibitors when they add cost and side effects without clear benefit.

Dose selection is where many transitions go wrong. GLP-1 and related drugs do not convert neatly from one to another, so clinicians should not assume that a milligram amount on one product equals the same effect on another. Marci Laudenslager, an obesity medicine physician at Johns Hopkins University School of Medicine in Baltimore, said these drugs should generally be started at a low dose and increased gradually as tolerated. “Obesity medications should rather be initiated at a low dose and up-titrated gradually as needed based on tolerability and clinical response,” Laudenslager said. She added that patients who moved up smoothly the first time may tolerate a faster increase, while those who had difficulty often need a slower ramp.

Susan Spratt, a professor of medicine and family medicine at Duke University School of Medicine in Durham, North Carolina, said one of the common mistakes is resuming therapy too aggressively after a gap. If a patient has been off the medicine for more than two or three weeks, she said, the dose usually needs to be built back up rather than restarted at an equivalent level. That matters because nausea, constipation and appetite changes can return when a new agent is introduced. Clear counselling can prevent patients from mistaking expected side effects for failure and stopping treatment too soon.

The stakes are even higher for people with type 2 diabetes, especially if they also use insulin or a sulfonylurea. Soudah said glucose should be checked at least daily for the first four weeks after a switch and after each dose increase, because blood sugar can fall quickly once the new medicine begins working. Clinicians may also need to trim insulin or sulfonylurea doses temporarily to reduce the risk of hypoglycaemia. The American Diabetes Association says continuous glucose monitoring can be especially useful because A1c does not show day-to-day swings, a point Spratt echoed by noting that patients may have unrecognised low glucose overnight.

Laudenslager said follow-up should be prompt, ideally within a month, so clinicians can review safety, tolerability and response. She also said the goal during a transition should be stability rather than further weight loss, since appetite, intake and gastrointestinal symptoms may fluctuate while a patient adjusts. Extra caution is warranted in older adults and in people with a history of pancreatitis, gallbladder disease, frailty or complex drug regimens, because switching may affect hydration, food intake and even muscle or bone mass. For primary care teams, the practical lesson is that these transitions work best when they are deliberate, individualised and closely monitored.