Foundayo vs. Mounjaro: what changes if you have type 2 diabetes

Mounjaro is tirzepatide, a weekly injection that acts on GIP and GLP-1 receptors. Its label covers blood sugar control in type 2 diabetes for adults and children aged 10 and older. It also covers lowering major cardiovascular events in adults with type 2 diabetes at high risk. Doses run from 2.5 mg to 15 mg (10 mg for children).

Foundayo is orforglipron, a once-daily tablet that acts on the GLP-1 receptor only. Its label covers weight reduction and maintenance in adults with obesity, or overweight with a related condition. That includes people with type 2 diabetes, but it is not labeled to treat blood sugar. Tablets go from 0.8 mg up to 17.2 mg, raised no sooner than every 30 days.

So for someone with diabetes, Mounjaro treats the diabetes directly. Foundayo treats the weight, and any blood sugar benefit is secondary.

The two have never been tested against each other. Here is what each has in people with type 2 diabetes.

Foundayo in diabetes and obesity. The second pivotal trial on the Foundayo label enrolled 1,613 adults with type 2 diabetes, a BMI of 27 or more and an HbA1c of 7% to 10%. At 72 weeks, weight fell 5.1%, 7.0% and 9.6% on the three doses, against 2.5% on placebo. At 17.2 mg, 45.6% lost at least 10%, versus 9.2% on placebo. In the separate ACHIEVE-3 trial (Lancet 2026), orforglipron 17.2 mg lowered HbA1c by 2.2 points at 52 weeks, versus 1.4 for oral semaglutide 14 mg. Weight fell 9.2% versus 5.3%, per Lilly. That trial was open-label.

Mounjaro in diabetes. In SURPASS-2, tirzepatide lowered HbA1c by 2.01 to 2.30 points over 40 weeks, against 1.86 for injected semaglutide 1 mg. SURPASS-CVOT, in 13,299 people with diabetes and heart disease, found tirzepatide noninferior to dulaglutide for heart attack, stroke and cardiovascular death. That trial underpins Mounjaro's August 2026 heart indication.

Because the comparators differ, these HbA1c figures cannot be set side by side.

Both labels warn about the same class effects: stomach upset, pancreatitis, gallbladder disease, kidney injury from dehydration and aspiration during anesthesia.

Foundayo at 17.2 mg, in its pooled trials: nausea 35%, diarrhea 25%, constipation 24% and vomiting 24%, versus 10%, 11%, 9% and 4% on placebo. About 10% stopped at that dose because of side effects.

Mounjaro lists nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion and belly pain as most common. In SURPASS-2, nausea affected 17% to 22%.

For people with diabetes, two warnings matter on both labels. Low blood sugar becomes more likely with insulin or a sulfonylurea, so those doses may need lowering. Diabetic retinopathy can worsen, so people with a history of it need monitoring. Foundayo was not studied in people with retinopathy needing urgent treatment. Both drugs affect birth-control pills after dose changes. Both carry a thyroid C-cell tumor boxed warning.

Mounjaro is the stronger fit if you have type 2 diabetes and need blood sugar lowered, particularly with heart disease. It is approved for both, with outcome data behind the heart claim. It is also the option for a child aged 10 or older with type 2 diabetes.

Foundayo may fit if weight is the main target, injections are the barrier, and your diabetes is otherwise managed. Its label trial in people with diabetes showed weight loss, but it holds no blood sugar indication yet. Its many drug interactions through CYP3A4 need a check against your medicine list.

If you do not have diabetes, Mounjaro is off-label for weight. Compare Foundayo with Zepbound instead, which is the same tirzepatide under a weight label.

Neither fits with medullary thyroid carcinoma or MEN2 in your personal or family history, or during pregnancy. At Temi, Foundayo is filled by LillyDirect at $149 for 30 days of the 0.8 mg tablet [usetemi.com/medications/foundayo, verified Sep 28, 2026].