Disclaimer: This article is for general health information only and is not an advertisement for, or recommendation of, any medicine. GLP-1 medicines are prescription medicines and may not be suitable for everyone. Speak to your doctor or pharmacist for advice.
GLP-1 medications – including semaglutide, tirzepatide and liraglutide – are increasingly used to manage type 2 diabetes and support weight loss.
They work by imitating the action of the hormone glucagon-peptide 1, which regulates your blood sugar level and directly inhibits the appetite centre of your brain, explain Dr Angela Murphy, a specialist physician in Gauteng with a particular interest in endocrinology, diabetes and obesity. They also slow the emptying of the stomach, increasing feelings of fullness and so further reducing appetite.
The benefits are substantial for those who have type 2 diabetes or are overweight or obese, which puts them at risk of cardiovascular disease (especially heart disease and stroke), musculoskeletal disorders such as osteoarthritis, and some cancers (endometrial, breast and colon). These conditions can cause premature death and disability.
“GLP-1s offer the best medical intervention to date for overweight and obesity,” says Dr Murphy. “But like most medications, they can have side effects. These are mostly mild but it’s crucial to discuss them with your doctor, who can monitor them.”
The most common side-effects are gastrointestinal, such as nausea, indigestion and bloating, occasionally with vomiting, diarrhoea or constipation. They generally dissipate once you develop tolerance, and can be reduced by eating small portions, chewing food well and avoiding fatty meals, Dr Murphy says.
Some people can be at risk for more severe side effects, ranging from pancreatitis and gastroparesis (delayed stomach emptying) to bowel obstruction, bile duct blockage, gallstone attacks, medullary thyroid cancer and acute kidney injury.
This makes it important for you to work with your healthcare professional so they can monitor key health markers.
Key markers to monitor
For metabolic health: blood glucose
Why? GLP-1s regulate blood sugar but they do not decrease the levels below normal. However, some people may be at risk of hypoglycaemia (low blood glucose) if they are on other glucose-lowering medications for diabetes treatment (sulphonylureas and insulin), or if they have significant anorexia or vomiting. Low glucose levels cause symptoms such as dizziness, shakiness, sweating, palpitations and confusion.
For kidney function: creatinine and electrolytes
Why? GLP-1s can cause dehydration, nausea and vomiting, which put a strain on the kidneys. Elevated creatinine and imbalanced electrolytes indicate reduced kidney filtration or potential disease, making regular checks essential for safety.
For liver enzymes: ALT and AST
Why? ALT (alanine aminotransferase) and AST (aspartate aminotransferase) are liver enzymes that leak into the bloodstream when liver cells are damaged or inflamed, so they are key markers for liver health.
For body composition: muscle mass VS fat
Why: Rapid weight loss often includes muscle loss, which can lead to lower energy, mobility problems and difficulty maintaining weight loss. Monitoring muscle loss can help you adjust your protein intake and exercise. “Moderate intensity exercise for 150 minutes a week is recommended, ideally a mixed programme of cardio and resistance training,” says Dr Murphy.
For your heart: heart rate and blood pressure
Why? GLP-1s can raise heart rate (by around three beats a minute). Regular tracking helps monitor for any potential issues arising from this. “However, GLP-1s improve cardiovascular health significantly, despite this increase in heart rate,” she says.
For your nutritional status: B12, iron, vitamin D levels
Why: Due to significantly reduced food intake, you may experience nutrient deficiencies. Tests can determine this.
For GI symptoms: Nausea, vomiting, diarrhoea constipation
Why: These are the most common side effects of GLP-1s, especially when starting or increasing doses. They are the main reason for treatment discontinuation, making it important that they be monitored and addressed.
How often should I monitor key markers?
Discuss a schedule with your healthcare professional. They will typically arrange a comprehensive metabolic panel, including a fasting blood glucose test, HbA1c and lipid panel, before beginning GLP-1 medication. Kidney and liver blood tests are often performed as well, says Dr Murphy. “Follow-up tests will be recommended depending on baseline conditions and a person’s overall health.”
They may also advise regular monitoring of your weight and nutritional intake. “I ask all my patients to follow up with one of the registered dieticians I work closely with,” she says.
Bottom line is that GLP-1s lead to widespread changes in your body. By tracking them, you can avoid problems and feel confident that your treatment is working well.
Clicks Clinic Service: Personalised Support for Weight Management & Diabetes Care
Selected Clicks Clinics now offer Weight Management Support consultations, including clinically supervised weight management support, and ongoing monitoring of weight, blood pressure and other markers. Find out more and book an appointment.