Introduction
Prediabetes means your blood sugar levels are higher than normal, but not high enough to be diagnosed as type 2 diabetes. Diet-controlled diabetes is when you have type 2 diabetes that is managed through lifestyle changes (such as diet and exercise) without the need for medication.
GLP-1 medicines such as Wegovy (semaglutide) and Mounjaro (tirzepatide) are well-known for supporting weight loss. They also improve blood sugar control, which makes them especially helpful for people with prediabetes or diet-controlled diabetes. With the right monitoring and support from your GP, these treatments can reduce the risk of progression to diabetes and improve overall health.
How GLP-1 Medicines Work
Wegovy and Mounjaro belong to a group of medicines called GLP-1 receptor agonists (Mounjaro also acts on another hormone called GIP). They work by:
- Helping you feel full sooner and for longer.
- Slowing digestion so you eat less.
- Supporting your body to use insulin more effectively.
For people with prediabetes or diet-controlled diabetes, these changes lower blood sugar and reduce insulin resistance (1,2).
Effects on Prediabetes and Diet-Controlled Diabetes:
Prediabetes
In the STEP trials, many participants with prediabetes returned to normal blood sugar levels after one year of semaglutide treatment (3).
In the SURMOUNT-1 trial, up to 95% of participants with prediabetes normalised their blood sugar after 72 weeks of tirzepatide treatment (4).
Diet-Controlled Type 2 Diabetes
GLP-1 medicines reduce HbA1c (a measure of long-term blood sugar) even in people who are not on other diabetes medicines (5).
They can delay the need for additional treatment, such as metformin or insulin.
Weight loss from GLP-1 therapy reduces insulin resistance, helping some patients maintain diabetes control through diet and lifestyle alone (6).
What Patients Should Consider:
1. Before starting treatment
Tell your GP you are starting Wegovy or Mounjaro so this is recorded in your medical notes and ask for a baseline HbA1c test, if you do not have any recent results.
2. During treatment
Continue regular HbA1c monitoring with your GP (usually every 3–6 months).
Be aware: anti-diabetic medicines may interact with GLP-1 weight-loss treatments, leading to serious side effects.
If your GP starts you on any diabetic medication, inform your prescriber immediately so your treatment plan can be reviewed.
Maintain lifestyle changes — healthy eating, regular physical activity, and good sleep are key alongside medication.
3. After weight loss
If your HbA1c improves into the normal range, your GP may reduce the frequency of checks but at least annual monitoring is recommended.
Never stop or change any prescribed medicines without GP advice.
Keep up lifestyle changes to help prevent blood sugar from rising again.
4. When to Seek Medical Advice Urgently
See your GP or seek urgent help if you notice:
- Excessive thirst and frequent urination
- Sudden unexplained weight loss
- Severe tiredness
- Blurred vision
- Recurrent or severe hypoglycaemia
These may suggest your blood sugar control is worsening or has progressed to diabetes requiring additional treatment.
References
Nauck MA, Meier JJ. GLP-1 receptor agonists and prediabetes: Mechanisms and benefits. Diabetes Obes Metab. 2019;21 Suppl 2:4–18.
American Diabetes Association. Prevention or delay of type 2 diabetes: Standards of medical care in diabetes—2023. Diabetes Care. 2023;46(Suppl 1):S41–7.
Rubino DM, Greenway FL, Khalid U, O’Neil PM, Rosenstock J, Sørrig R, et al. Effect of semaglutide 2.4 mg on glycaemic status in participants with obesity and prediabetes: STEP program results. Diabetologia. 2022;65(1):171–84.
Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205–16.
Wilding JPH, Frias JP, D’Alessio D, Patel P, Tong C, Pietzsch J, et al. Efficacy and safety of once-weekly semaglutide vs sitagliptin as add-on to metformin in patients with type 2 diabetes. Lancet Diabetes Endocrinol. 2019;7(7):528–39.
Lean MEJ, Leslie WS, Barnes AC, Brosnahan N, Thom G, McCombie L, et al. Primary care-led weight management for remission of type 2 diabetes (DiRECT): An open-label, cluster-randomised trial. Lancet. 2018;391(10120):541–51.