A number of supplements are marketed for blood sugar, and some do have a modest effect. That is the problem rather than the benefit: anything that lowers blood sugar adds to what your diabetes medicine is already doing, and the combined effect is not something either was dosed for.
This matters most if you take insulin or a sulfonylurea such as gliclazide, since those can cause hypoglycaemia on their own.
Common side effects reported with this supplement or ingredient
The effect to watch for is not a side effect of the supplement but a low blood sugar episode: shakiness, sweating, hunger, a pounding heartbeat, irritability, difficulty concentrating, or confusion. Treat it as you would any hypo and check your readings. See low blood sugar on diabetes medicine.
If your readings have shifted since starting a supplement, in either direction, that is worth reporting rather than adjusting around.
Possible interactions with medicines, chronic conditions or pregnancy
Supplements commonly marketed for blood sugar include cinnamon, chromium, berberine, bitter melon, fenugreek and alpha-lipoic acid. Evidence for their effect varies considerably, but where there is an effect there is potential to add to your medicine.
Other supplements matter for different reasons:
- St John’s Wort, which affects how many medicines are processed. See St John’s Wort interactions.
- Fibre supplements, which can affect how medicines are absorbed if taken at the same time.
- Vitamin B12, relevant in the other direction: long-term metformin reduces B12 absorption, so this may be recommended rather than avoided. See metformin side effects.
- Products affecting kidney function, which matters because several diabetes medicines depend on the kidneys.
Sugar content in some syrups and chewable supplements is also worth checking.
Who should speak to a healthcare professional before using it?
Anyone taking insulin or a sulfonylurea, anyone with reduced kidney function, anyone with diabetic eye or nerve complications, and anyone pregnant.
Most importantly, anyone considering a supplement as a replacement for prescribed treatment. No supplement substitutes for diabetes medicine, and stopping treatment in favour of one risks serious and lasting harm through sustained high blood sugar. If cost or side effects are behind the idea, raise that directly, since there are usually other options.
Dose, product-quality and stacking risks
Supplements in South Africa are regulated as complementary medicines, and content can vary between products, so the size of any blood sugar effect is not predictable from the label. See how supplements are regulated.
Products promising dramatic blood sugar results deserve particular caution, since this is a category where undeclared pharmaceutical ingredients have been found. See unsafe supplements.
When to stop and get medical advice
Get emergency help for severe hypoglycaemia: confusion, inability to swallow safely, seizures or loss of consciousness.
Contact your diabetes team if readings have changed since starting a supplement, if you are having more low readings than usual, or if you have started something without telling them. Monitor more closely for the first weeks after starting anything new, and take the product to your next appointment.
Stop the supplement rather than your diabetes medicine, and ask.
Related supplement safety guides
- Supplement side effects
- Supplement and medicine interactions
- When to see a doctor about a supplement
- Unsafe supplements in South Africa
- Report a supplement side effect
See also diabetes medication side effects.
Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.