Semaglutide for type 2 diabetes is a GLP-1 receptor agonist that lowers blood glucose by acting on the pathway a gut hormone uses after a meal. Two brand products are approved for glycemic control in adults with type 2 diabetes: the once-weekly injection Ozempic and the once-daily tablet Rybelsus. Both now carry additional approved indications for cardiovascular risk. Wegovy is the same molecule dosed for chronic weight management and is not a diabetes medicine. Compounded semaglutide is a fourth category again, and that is the distinction people most often get wrong.

How semaglutide lowers blood sugar

Three mechanisms run together.

Glucose-dependent insulin secretion. Semaglutide prompts the pancreas to release insulin while blood glucose is elevated, and the signal fades as glucose normalizes. That dependence is why the molecule on its own carries a low risk of hypoglycemia, unlike insulin or a sulfonylurea, which push glucose down regardless of where it already sits.

Glucagon suppression. Less glucagon means the liver releases less stored glucose between meals.

Delayed gastric emptying. Food leaves the stomach more slowly, flattening the rise after a meal. This is also where most of the nausea comes from.

The receptor-level detail sits in how semaglutide works. The rest of this article is about what those mechanisms produced in trials.

What the trials measured in HbA1c

The SUSTAIN program tested the injection and PIONEER tested the tablet. Both report in HbA1c, the roughly three-month average of blood glucose that diabetes care is managed against.

SUSTAIN 7 was a head-to-head trial against dulaglutide in 1,201 adults on metformin. At week 40, HbA1c had fallen 1.5 percentage points on semaglutide 0.5 mg and 1.8 points on 1.0 mg, against 1.1 and 1.4 points on the two dulaglutide doses; body weight fell 4.6 kg and 6.5 kg respectively (Pratley et al., Lancet Diabetes Endocrinol 2018). Gastrointestinal disorders were the most frequent adverse events and the most common reason for stopping, on both drugs.

PIONEER 1 tested the oral form as monotherapy in 703 adults managed by diet and exercise alone, with a mean baseline HbA1c of 8.0%. Placebo-adjusted reductions at 26 weeks were 0.6, 0.9 and 1.1 percentage points at 3 mg, 7 mg and 14 mg (Aroda et al., Diabetes Care 2019).

Those are trial averages, not predictions for any one person. Dose is set by the prescriber and raised slowly; the semaglutide dosage schedule explains how that titration normally runs and why it is deliberately unhurried.

Heart and kidney outcomes, not only glucose

SUSTAIN-6 randomized 3,297 adults with type 2 diabetes at high cardiovascular risk to semaglutide or placebo for 104 weeks. The composite of cardiovascular death, non-fatal myocardial infarction and non-fatal stroke occurred in 6.6% on semaglutide against 8.9% on placebo (hazard ratio 0.74) (Marso et al., NEJM 2016). Retinopathy complications were reported more often in the semaglutide group, which is why the label tells prescribers to monitor anyone with a history of diabetic retinopathy.

SOUL ran the same test for the tablet. Among 9,650 adults with type 2 diabetes and atherosclerotic cardiovascular disease, chronic kidney disease or both, followed a median of 49.5 months, the same composite occurred in 12.0% on oral semaglutide against 13.8% on placebo (hazard ratio 0.86) (McGuire et al., NEJM 2025). That trial supported the cardiovascular indication added to the tablet's label in October 2025.

FLOW looked at kidneys. In 3,533 adults with type 2 diabetes and chronic kidney disease, the risk of a major kidney disease event was 24% lower on semaglutide 1.0 mg than on placebo (hazard ratio 0.76), and death from any cause 20% lower (Perkovic et al., NEJM 2024). The injection's label now includes reducing the risk of sustained eGFR decline, end-stage kidney disease and cardiovascular death in that group.

Semaglutide for type 2 diabetes versus tirzepatide

Tirzepatide is also approved for glycemic control in adults with type 2 diabetes, under a different brand name, and it acts at two receptors rather than one. SURPASS-2 compared them directly in 1,879 adults with a mean baseline HbA1c of 8.28%: the estimated change at 40 weeks was −1.86 percentage points on semaglutide 1 mg against −2.01, −2.24 and −2.30 points on tirzepatide 5 mg, 10 mg and 15 mg (Frías et al., NEJM 2021). Gastrointestinal events were common on both.

That does not settle the choice for an individual. Tolerability, cost, what a plan covers and what someone has already tried all feed into it, and a prescriber weighs those alongside the trial data rather than in place of it.

Who the label rules out

The brand labeling is specific about this, and the screening questions in any legitimate intake follow it:

  • A personal or family history of medullary thyroid carcinoma, or MEN 2. A contraindication, on the basis of thyroid C-cell tumor findings in rodents.
  • Serious hypersensitivity to semaglutide or any excipient in the product.
  • Type 1 diabetes. The approved indication covers adults with type 2 diabetes only.
  • Insulin or a sulfonylurea alongside it. Not an exclusion, but the combination raises hypoglycemia risk and often means the other agent's dose comes down.
  • Pancreatitis and diabetic retinopathy history. Not automatic exclusions either, but both are weighed and monitored.
  • Pregnancy and breastfeeding.

What turns up in practice is mostly gastrointestinal and mostly early; semaglutide side effects covers that in detail.

Brand, compounded, and the distinction people miss

Through Promise, semaglutide is dispensed as a compounded medication, which is different from an FDA-approved product: the formulation offered here is not FDA-approved, and it is not an approved treatment for type 2 diabetes. Compounded medications are not reviewed by the FDA for safety, effectiveness or quality.

A compounded medication is prepared by a licensed U.S. pharmacy for an individual patient against a prescription. That is a lawful, regulated activity with its own oversight framework — but the preparation has not been through the review the branded products went through, and it is not the branded product. A licensed provider may still prescribe a compounded formulation where they judge it appropriate, and that decision is between you and your doctor.

The third option is the one worth avoiding: semaglutide sold online without a prescription, as laboratory material, with no clinician attached and no recourse if the contents are wrong.

What a first visit actually asks

The intake for a GLP-1 is one of the longer questionnaires in this category, because the screening is heavier: current and past diagnoses, every medication taken, thyroid and pancreatic history, kidney function, prior GLP-1 experience, pregnancy status, and the state you live in. Getting semaglutide prescribed walks through the route end to end.

A licensed provider in Promise's prescriber network reviews every request and prescribes only when semaglutide is appropriate for you. Not everyone qualifies, and being declined is a real outcome — usually for a specific reason worth knowing.