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.
Glucagon-like peptide-1 (GLP-1) receptor agonists are medications, mostly self-injected, which were initially formulated and marketed for the treatment of diabetes and are now being increasingly used for weight loss.
They work by mimicking the action of the hormone glucagon-peptide 1, which regulates blood sugar levels. They stimulate the pancreas to release insulin when blood sugar is high, especially after meals, and supress the release of glucagon, a hormone that raises blood sugar.
They also affect the brain regions that control appetite, reducing hunger and increasing feelings of fullness, and slow the rate at which the stomach empties, inhibiting its peristalsis while increasing the contraction of the pyloric region, adding to the sense of fullness and potentially affecting the way the body processes food, according to a study in the journal Diabetes and Metabolism.
What are the common types of GLP-1 medicines?
Semaglutide is one of the best-known medicines in the GLP-1 class and is used internationally for the management of type 2 diabetes and obesity. Other medicines in this class include tirzepatide, liraglutide, dulaglutide and lixisenatide.
“The newest agent in the incretin class is tirzepatide, which is a GLP-1/GIP (gastric inhibitory polypeptide) agonist,” says Dr Angela Murphy, a specialist physician in Gauteng with a particular interest in endocrinology, diabetes and obesity. “By acting at two receptors, it has shown even greater benefit with glucose control and weight loss.”
In South Africa, several medicines in this class are registered for the treatment of type 2 diabetes, including semaglutide, tirzepatide, liraglutide, dulaglutide and lixisenatide. Some are also approved for weight management. The availability and approved uses of these medicines may vary by country and may change over time.
Who are GLP-1s for?
GLP-1 agonists are at present primarily intended for adults with type 2 diabetes – the country’s leading killer of women and second most common underlying cause of death overall, according to diabetes specialist nurse Michael Brown, head of the CDE (Centre for Diabetes and Endocrinology) Academy.
They are also being used for people with obesity, which is a major contributor to diabetes – half of all adults in South Africa are overweight or obese, reports Dr Micheal Kofi Boachie, a researcher at the SAMRC/WITS Centre for Health Economics and Decision Science. Around 12 million South Africans suffer from weight-related conditions for which they receive treatment in the public sector, including not only diabetes, but hypertension, cardiovascular disease, arthritis and certain cancers – diseases that cause life-long illness, disabilities and premature death.
Boachie and colleagues have calculated that overweight and obesity cost the health system around R33 billion a year, with an annual per person cost of around R2,769. It is against this that costs of a solution such as a GLP-1 agonists need to be weighed.
How safe are they?
“There is no magic bullet for weight loss,” says Johannesburg-based dietitian Lila Bruk. “To determine if you’re a suitable candidate for GLP-1 agonists, it’s important to see your health care practitioner.”
Like all medications, they have drawbacks. Side effects may include nausea, indigestion, bloating, and less commonly, vomiting and diarrhoea, although these can be reduced by eating small portions, avoiding fatty meals and chewing food well, and are generally short-lived.
A bigger drawback, says Bruk, is that these drugs may need to be used long-term to keep weight off, and it is too early to know the effects of long-term use.
How effective are they?
“There’s no doubt GLP-1 receptor agonists offer the best medical intervention to date for overweight and obesity,” says Dr Murphy. “If used as part of a holistic approach to a healthy lifestyle, with sensible eating and regular exercise, significant sustained weight loss may be achieved.”
It is crucial that GLP-1s be taken under medical supervision and obtained on prescription through reputable sources. The South African Health Products Regulatory Authority recently warned about “the proliferation of falsified, compounded and substandard GLP-1-containing products being made available via websites, social media and other informal channels. They pose a health risk to the public.”
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