Mounjaro and blood sugar

What sources report

Mounjaro for type 2 diabetes is the use FDA approved first, on May 13, 2022.² The figures below come from the trials summarized in the US label, all in people with type 2 diabetes, and from FDA approval records.¹² Each one is a group average, not a forecast for one person.

How Mounjaro acts on blood sugar

Tirzepatide, the active ingredient, switches on two receptors: the GIP receptor and the GLP-1 receptor.¹ The label describes four effects that bear on glucose:

• Insulin: it strengthens both the first and the second phase of insulin release, in a glucose-dependent way.⁵
• Glucagon: it lowers glucagon, also in a glucose-dependent way.⁵ After 28 weeks on 15 mg, fasting glucagon was 28% lower and glucagon after a mixed meal 43% lower, while placebo showed no change.⁶
• Insulin sensitivity: in a clamp study of people with type 2 diabetes, insulin sensitivity improved after 28 weeks of treatment.¹⁸
• Stomach emptying: it slows the stomach, most strongly after the first dose, and the effect fades over time.⁷

In the 40-week trial where Mounjaro was the only diabetes medicine, no one taking it had glucose below 54 mg/dL, against 1% on placebo, and no one had a severe episode.¹ Combinations with insulin or a sulfonylurea change that picture, as shown further down.

Trial by trial

The label reports five glucose trials in adults and one in children. Where it gives a range, the range spans the doses tested.¹

SURPASS-1 participants started at an HbA1c of about 8.0%. By week 40, 78% to 85% of those on Mounjaro had moved below 7%, compared with 23% on placebo.¹

SURPASS-2 set Mounjaro against semaglutide 1 mg, one of the dose steps on the Ozempic label.¹¹¹ The label's text names the 10 mg and 15 mg results as statistically significant, but its results table marks all three doses as statistically superior to semaglutide.¹ The published trial report also found all three doses noninferior and superior.¹⁰

In the two insulin comparisons, SURPASS-3 and SURPASS-4, the label's tables mark all three Mounjaro doses as superior to daily basal insulin for HbA1c, and body weight fell on Mounjaro while it rose on insulin.¹ Weight results from every trial in the table are laid out on Mounjaro and weight loss.

Combining Mounjaro with other diabetes medicines

Low blood sugar risk depends on the combination. With basal insulin, glucose fell below 54 mg/dL in 14% to 19% of people on Mounjaro against 13% on placebo, and severe episodes reached 2% on 10 mg.¹ With a sulfonylurea, over up to 104 weeks, 9.9% to 13.8% had glucose below 54 mg/dL, and severe episodes stayed at 0.6% or less.¹ When Mounjaro starts, the label tells prescribers to consider lowering the sulfonylurea or insulin dose.¹ Rates for each combination sit on Mounjaro side effects.

Pills taken by mouth can be affected too. Because Mounjaro slows stomach emptying, it can change how other pills are absorbed, so drugs with a narrow safety margin, such as warfarin, need monitoring.¹

Children 10 and older

FDA extended the blood sugar use to children 10 and older with type 2 diabetes on December 19, 2025.²¹ The use is supported by SURPASS-PEDS, a 30-week randomized, double-blind, placebo-controlled trial in 99 patients, followed by a 22-week open-label extension.⁹ Children had more vomiting, abdominal pain and low blood sugar than adults.¹ Their dose ceiling is 10 mg once weekly, and the label does not recommend the KwikPen for self-injection by children.¹ Safety and effectiveness under age 10 have not been established.¹

Heart risk in type 2 diabetes

Since August 27, 2026, Mounjaro has a second US use, still within type 2 diabetes: reducing the risk of major cardiovascular events (cardiovascular death, non-fatal heart attack or non-fatal stroke) in adults at high risk of them.³¹ It is based on SURPASS-CVOT, in which 13,299 adults who had type 2 diabetes plus established heart or blood vessel disease took Mounjaro (up to 15 mg) or dulaglutide 1.5 mg weekly, with a median follow-up of 210.1 weeks.¹ A first such event occurred in 12.1% against 13.0% (hazard ratio 0.92): non-inferior, but not shown to be superior.¹ Full results: Mounjaro benefits and uses.

The 2.5 mg dose since August 2026

The same approval letter lets 2.5 mg, until then a starting step only, be used for ongoing glycemic control.³⁴ A model in the label, not a trial, projects about a 1.8-point HbA1c fall at that dose after 52 weeks; the schedule is on Mounjaro dosage.¹

What the label says

• Use: with diet and exercise, to improve glycemic control in adults and children 10 and older with type 2 diabetes.¹
• Dose steps: 2.5 mg once weekly to start; if more glycemic control is needed, increases of 2.5 mg after at least 4 weeks on the current dose, to a maximum of 15 mg in adults and 10 mg in children.¹ The prescriber sets and adjusts the dose.
• Low blood sugar: the risk, including severe episodes, rises with a sulfonylurea or insulin.¹
• Diabetic eye disease: rapid improvement in blood sugar has been linked to temporary worsening of diabetic retinopathy, so people with a history of it are monitored and report any vision changes.¹
• Kidneys and liver: no dose adjustment is recommended for kidney or liver impairment. Acute kidney injury, sometimes needing dialysis, has been reported, mostly in people dehydrated by stomach side effects.¹
• Not recommended: in severe gastroparesis.¹
• Who should not use it: people with a personal or family history of medullary thyroid carcinoma or MEN 2, or with a known serious allergy to tirzepatide or any ingredient.¹
• Boxed warning: thyroid C-cell tumors developed in rats given tirzepatide; whether the same happens in humans is not known.¹

Read next

The Mounjaro profile covers the medicine as a whole, Mounjaro dosage gives the label schedule and Mounjaro side effects the reported reactions. The molecule's wider glucose research is on Tirzepatide and blood sugar, and the head-to-head with semaglutide is set out in Mounjaro vs Ozempic. The wider goal page is Peptides and blood sugar.