Incretins Spread Beyond Glucose as the Compounding Window Closes

Incretin biology is widening its reach this week: trials now test it across cannabis, alcohol, and methamphetamine use disorders, and STAT raises a fresh GLP-1 rationale in pulmonary hypertension [7][8][9][18]. At the same time the FDA moves to exclude semaglutide, tirzepatide, and liraglutide from the 503B bulks list, closing the compounding-supply era, just as the first genetically defined targets enter first-in-human work [21][10][11].

Incretins as neuropsychiatric tools

Three early-phase programs now test incretins against substance use: tirzepatide in cannabis use disorder [7], mazdutide in alcohol use disorder [8], and semaglutide in methamphetamine use disorder via the SHIFT Study [9]. These are not-yet-reported trials, with two not yet recruiting and one active but not recruiting. A separate Phase 4 program examines vascular and neurocognitive effects of semaglutide-driven weight loss [12], and STAT raises a distinct GLP-1 rationale in pulmonary hypertension [18].

So what: Investigators are probing how far incretin biology reaches into reward and organ pathways; clinicians should track these as hypothesis-generating, since none has reported efficacy.

The genetic-target generation enters the clinic

Arrowhead's ARO-INHBE begins first-in-human dosing in obesity with and without type 2 diabetes, benchmarked against tirzepatide [10]. Regeneron's ALN-PNP enters Phase 2a in homozygous PNPLA3-related MASLD, tested with and without a GLP-1 receptor agonist [11]. Both are recruiting and pair RNA-based approaches with established incretin comparators.

So what: The pipeline is shifting toward genetically defined targets layered onto incretins; the strategic question is additivity, and answers remain years out.

Supply and access tighten around the leaders

The FDA proposes excluding semaglutide, tirzepatide, and liraglutide from the 503B bulks list, which would curtail compounded supply [21]. Lilly's European obesity-pill launch strategy is being reshaped by most-favored-nation pricing pressure [16], and the company faces scrutiny over special access to its new obesity drug [13][14]. U.S. health spending rose sharply in 2025, attributed partly to GLP-1 uptake [17].

So what: The binding constraint on this category has moved from biology to access economics; consolidation toward branded supply will reshape who gets treated and at what cost.

Practice signals beyond the GLP-1 story

The FDA approved teplizumab for certain pediatric patients with recently diagnosed stage 3 type 1 diabetes [19] and cleared the first over-the-counter continuous glucose monitor for children [20]. In the literature, a Lancet Diabetes & Endocrinology piece argues intermittent fasting now warrants guideline attention given more than 225 trials, including nearly 40 in diabetes or prediabetes [2].

So what: Type 1 immunomodulation and pediatric monitoring are advancing in parallel with obesity headlines; dietary guidance may also be due for revision.

The weekly read across the metabolic field — every claim numbered to its source, graded by where the evidence comes from. The weekly is the field in motion; the monthly issue is the synthesis.