Updated 16 February 2017

Diabetic products: beware of side effects

Many diabetics don't realise that some diabetic products taken together with prescription meds could interfere with blood glucose control and lead to hypoglycaemia, DietDoc warns.


Last week when we honoured World Diabetes Day I was made aware of how many non-prescription products people with diabetes tend to use. It is only human to seek help if your blood sugar levels keep on soaring above the required values and if you constantly gain or lose weight due to your diabetes.

A problem arises because most patients do not realise that many of the over-the-counter products they take together with their regular medications, may have what are called "additive effects". Such additive effects can make you feel very ill and cause problems, particularly at times when you have other mild illnesses such as colds or an upset tummy.

What is an additive effect?

According to medical dictionaries an additive effect is "an effect in which the two substances or actions used in combination produce a total effect that equals the sum of the individual effects".

So let’s say you can achieve a reduction in blood glucose values with Glucophage of X% and you now also take an over-the-counter product which may reduce your blood sugar levels by Y%, so that together these two products will lower your blood glucose by X% + Y% = Z%. Most diabetic and insulin resistant patients would think this is "wonderful!" and in some cases it may well be, but in many cases a reduction of Z% may be too much and plunge the patient into hypoglycaemia.

Symptoms of hypoglycaemia

As a diabetic, you have probably experienced the symptoms of hypoglycaemia more than once, but just to remind you how unpleasant and potentially dangerous this condition can be when your blood sugar levels plummet below the normal cutoff point, here is a typical list of hypoglycaemia symptoms:

a) Mild hypoglycaemia

  • shakiness, tremor
  • cold sweat
  • palpitations (irregular heartbeat or very fast heartbeat)
  • anxiety and irritability
  • hunger

b) Pronounced hypoglycaemia

These symptoms occur when your brain is starved of glucose

  • slowing down of performance and problems with concentration and reading
  • mental confusion with disorientation
  • slurred or rambling speech
  • irrational or strange behaviour
  • exhaustion and listlessness
  • convulsions and loss of consciousness (coma)

(Mahan et al, 2011)

No one wants to experience this type of distress and loss of dignity, so please keep in mind that you may be causing your hypoglycaemia by overdosing with too many other antidiabetic products in addition to your standard diabetic medication.

Mild illnesses

Colds and upset stomachs (diarrhoea or vomiting) affect all of us and we can usually shake them off within a day or two. However, if you are diabetic and develop any condition that affects your appetite and prevents you from eating regular meals and you continue taking additional non-prescription antidiabetic medications you may well trigger a hypoglycaemic episode.

Hopefully you have read the package insert and patient information leaflet for your standard diabetic medication(s) and have discussed how it (they) should be used in all types of circumstances including when you are ill, when you have suffered trauma of any kind and when you do strenuous exercise or when you travel and may find it difficult to have regular meals.

If this is not the case, please contact your doctor, pharmacist or the nurse at your diabetic clinic and ask him/her how you should use your standard diabetic medication(s) when you experience any of the above mentioned changes in your routine.

If you are well informed about your standard diabetic medication(s) then you will know that you may need to reduce your dose (to varying degrees) when you suffer from a mild illness. The safer option is to contact your doctor or pharmacist or healthcare professional if you are feeling ill to discuss if you need to reduce your dosage of diabetic medication and to what extent.

It is vital that you stop taking all over-the-counter or non-prescription antidiabetic drugs or products when you develop a cold or diarrhoea or vomiting or flu. If the illness has already made your blood sugar levels low, taking even more blood sugar lowering compounds may make your blood sugar drop so low that you sink into a coma.

Safety tips for diabetics

To avoid additive effects and developing hypoglycaemic crises if you use a self-selected combination of standard diabetic medication and non-prescription diabetes products, the following tips may help:

  • Always get to know how your prescription diabetic medications, including insulin, work, how they should be taken and how and when you need to adjust the dosage. If you are unsure in any way, go back to the doctor, pharmacy or clinic and ask one of your counsellors to explain in detail.
  • Always discuss the use of any other product that is advertised for diabetics such as over-the-counter or herbal medications, extracts or supplements, with the medical doctor who is treating your diabetes or with your registered dietician, before you spend money on purchasing a product that may be unnecessary. For example, by sticking to the low-fat, low-GI diabetic diet that your dietician prescribed for your and doing some daily exercise, you will be able to lower your blood sugar levels as effectively as by taking all kinds of products that have often not been tested scientifically or don’t have proven blood sugar lowering effects.
  • If you develop any of the above mentioned symptoms of hypoglycaemia, go for help especially if you live alone or are elderly. If you should faint or lose consciousness no one may be aware of your crisis and you may suffer permanent damage if you do not receive treatment immediately.
  • Be aware of additive effects and when in doubt query combinations of medications.

Diabetics are not the only ones who are exposed to the additive effects of medications (prescription and over-the-counter). Next week we will have a look at the effect of overdosing on vitamins and minerals.

- (Dr IV van Heerden, DietDoc, November 2012)

(Photo of woman taking pill from Shutterstock)

(Reference: Mahan LK et al, 2011. Krause’s Food and the Nutrition Care Process. 13th Edition. Elsevier Saunders, USA)

Read more:

I've got diabetes: what now?
First aid for diabetic emergencies
Diabetes 'tsunami' hits South Africa
Diabetic diet: all you need to know


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Dr. May currently works as a fulltime endocrinologist and has been in private practice since 2004. He has a variety of interests, predominantly obesity and diabetes, but also sees patients with osteoporosis, thyroid disorders, men's health disorders, pituitary and adrenal disorders, polycystic ovaries, and disorders of growth. He is a leading member of several obesity and diabetes societies and runs a trial centre for new drugs.

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