Who the warning mainly concerns
The Medication Guide describes low blood sugar as a risk for people with type 2 diabetes, particularly those who also take insulin or a sulfonylurea, and calls it both a serious and a common side effect in that group. The prescribing information adds that use with insulin and use in type 1 diabetes have not been evaluated. [1]
For people with diabetes, section 2.1 asks that blood sugar be checked before Wegovy® is started and during treatment, and the leaflet repeats that you should check it before and while you take the medicine. [1] The EU product information says semaglutide should not be used as a substitute for insulin, [2] and Novo Nordisk’s patient page lists low blood sugar in people with type 2 diabetes among the most common side effects. [4]
The type 2 diabetes trial in three documents
Study 3 (STEP 2) enrolled adults who had type 2 diabetes and a body-mass index of at least 27, managed by diet and exercise or up to three oral diabetes medicines, including sulfonylureas, and randomised them to Wegovy® 2.4 mg, semaglutide 1 mg or placebo for 68 weeks. [1][5] The trial’s main report found that adverse events overall were more frequent on 2.4 mg (87.6%) and 1 mg (81.8%) than on placebo (76.9%). [5]
| Measure and source | Placebo | Semaglutide 1 mg | Wegovy® 2.4 mg |
|---|---|---|---|
| People with a reading below 54 mg/dL (3.0 mmol/L), US [1] and Canada [3] | 2.5% | not given | 6.2% |
| Episodes per 100 patient-years, US [1] | 3.2 | 7.2 | 10.7 |
| Events per patient-year, EU [2] | 0.03 | not given | 0.1 |
| Severe episode | none | not given | 1 person (needed intravenous glucose) |
Reading the numbers
The main US adult table shows a row called “hypoglycemia in T2DM” with 6% on Wegovy® and 2% on placebo. A footnote explains it counts readings below 54 mg/dL, with or without symptoms, plus severe episodes needing another person’s help, in STEP 2 participants not on insulin. [1] Episodes per 100 patient-years counts repeat events: 10.7 means about eleven episodes for every hundred people followed for a year. The label reports it to show that 2.4 mg produced more episodes than 1 mg. [1]
The EU product information adds that hypoglycaemia was seen with and without a sulfonylurea, and that the single severe episode occurred in someone not taking one. [2] There are no low blood sugar figures for the 7.2 mg dose. [1]
Other medicines, and a trial that looked different
Section 6.1 says the risk was higher when Wegovy® was used with a sulfonylurea, and section 7.1 says prescribers may consider lowering the insulin or sulfonylurea dose when Wegovy® starts. [1] NIH explains that sulfonylureas and meglitinides are the two types of diabetes pills that can cause low blood glucose, alongside insulin. [6]
In STEP-HFpEF-DM, a trial in people with obesity-related heart failure and type 2 diabetes, clinically significant lows occurred in 4.2% on both semaglutide and placebo among those using a sulfonylurea and/or insulin, and the Canadian monograph reports no increased risk there. [2][3] In a trial of adults with MASH and type 2 diabetes, severe low blood sugar was reported in 2.2% on Wegovy® versus 0.5% on placebo. [3] The different trials enrolled different people, so their numbers are not interchangeable.
People without diabetes, and teenagers
Episodes of low blood sugar have been reported with GLP-1 medicines in adults without type 2 diabetes, but Wegovy® weight-reduction trials did not systematically capture them, so there is no rate. In the large cardiovascular trial in adults without diabetes, 3 serious episodes occurred on Wegovy® and 1 on placebo, and people with a history of bariatric surgery had more serious episodes on Wegovy® (2 of 87, 2.3%) than on placebo (none of 97). [1] The Canadian patient leaflet lists low blood sugar in people without diabetes as uncommon. [3]
For teenagers aged 12 and older with type 2 diabetes, section 8.4 says there are not enough data to tell whether the risk is higher, and asks for the same blood sugar checks and possible dose reductions of other diabetes medicines. [1]
Signs, triggers and what the plan should cover
- Signs in the Medication Guide: dizziness or light-headedness, sweating, shakiness, weakness, feeling jittery, blurred vision, slurred speech, confusion or drowsiness, anxiety, irritability or mood changes, hunger, headache and a fast heartbeat. [1] The Canadian leaflet adds cold sweat and cool, pale skin, and notes the signs may come on suddenly. [3]
- Low without symptoms: MedlinePlus explains that some people do not feel lows (hypoglycaemic unawareness) and may only find out when they faint. [7]
- Everyday triggers for people on glucose-lowering medicines, according to NIH: not eating enough carbohydrate, fasting (including before a procedure), more exercise than usual, alcohol without food, and being ill. [6]
- Overdose: the Medication Guide lists severe low blood sugar among the effects of taking too much Wegovy® and says to call your provider or Poison Help, or go to an emergency room. [1]
- Your plan: the Medication Guide asks you to talk with your provider about how to recognise and treat low blood sugar; [1] how much and what to take is part of the plan your diabetes team gives you.
Wegovy® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| A person with diabetes who becomes less alert, cannot be woken, has a seizure or passes out | Emergency number right away | Emergency | MedlinePlus [7]; Canadian leaflet [3] |
| Low blood sugar signs that do not improve after taking sugar as your plan says | Emergency room; do not drive yourself | Emergency | MedlinePlus [7] |
| Severe low blood sugar after injecting more Wegovy® than prescribed | Your provider, Poison Help or the nearest emergency room | Emergency | Medication Guide [1] |
| Any low-blood-sugar episode, or readings below your target, while on Wegovy® with insulin or a sulfonylurea | Your diabetes team the same day | Today | Medication Guide [1]; Wegovy® section 7.1 [1] |
| Shakiness, sweating or confusion if you do not have diabetes | Your prescriber | Today | Wegovy® section 6.1 [1]; Canadian leaflet [3] |
| A planned fast, procedure or big change in exercise while on glucose-lowering medicines | Your diabetes team beforehand | At your next appointment | NIDDK [6] |
