Energy drinks: are they safe?

Energy drinks can be the go-to solution when one is feeling tired. However, are they safe for people living with diabetes? Jessica Pieterse reviewed the latest research and some commonly found energy drinks on the SA market to attain insight.


When most of us think of energy drinks, we assume the caffeine will be sky-high compared to other drinks. Most energy drinks provide an average of 114mg caffeine per standard 455ml can, or 176mg caffeine per the larger 550ml can. This is surprisingly similar to a cup of filter coffee that contains on average 170mg caffeine per 250ml mug.

Though, not all drinks and food fare as closely. A standard 455ml can of energy drink has one and half times the caffeine than a cappuccino (75mg in 250ml) as well as 1,4 times than normal tea (80mg in 250ml), 2,8 to 3,8 times than sweetened fizzy drinks (30 – 40mg in 330ml), and almost 10 times than a chocolate bar (12mg in 40g).

It’s recommended to consume less than 300mg per day of caffeine, or 2,5mg caffeine per kg body weight per day. Meaning a 50kg person should keep caffeine below 125mg/day which is less than one large can of energy drink.

Consuming excessive amounts of caffeine can lead to trouble sleeping, anxiety, irritability, nervousness, rapid heart rate, headaches and dependency on caffeine.

Research behind caffeine consumption in people living with diabetes was surprisingly lacking. The Society for Endocrinology, Metabolism and Diabetes of South Africa (SEMDSA) 2017 guidelines give no mention of caffeine.


Energy drinks are consumed often for the caffeine boost, but people living with diabetes should be aware of the sugar contents of these drinks.

Energy drinks that contain sugar and not sweeteners, can offer 11 – 62g of sugar per can which equates to 3 to 16 teaspoons of sugar per can (440 – 550ml). Consuming 16 teaspoons of sugar in one seating would greatly raise blood glucose levels, and regular intake increase HbA1C levels.

We found six energy drinks that offer no sugar as they use sweeteners, such as sucralose, aspartame and acesulfame K. Drinks that use sweeteners will affect blood glucose levels much less. However, avoid large intakes of sweeteners as they may have negative effects on gut functioning.


Energy drink manufactures may use the fact that B vitamins are added as a selling point. B vitamins act as co-factors to support energy processes in the body. A dietary intake that is low in B vitamins can contribute to fatigue. Therefore, B vitamins contribute to boosting energy.

B vitamins are safe for people living with diabetes. People taking long-term Glucophage medication should supplement with vitamin B12. However, most drinks won’t provide sufficient levels of B12 needed. It should be noted that B vitamins are water-soluble and excessive amounts will be urinated out and not stored.

Energy-boosting ingredients

Energy drinks often contain ginseng and guarana. Guarana is a Brazilian plant that has seeds with four times the amount of caffeine found in coffee beans (on a percentage basis), along with other xanthines which also stimulate the central nervous system.

Ginseng comes from a root of a Panax plant. Although manufacturers claim ginseng increases energy and boosts the immune system, evidence is lacking. Ginseng has been shown to interact with immunosuppressive and blood pressure medications and as no warnings appear on the product, this could lead to serious effects. People living with diabetes should therefore, be very careful in taking herbal products as they are often on several medications.

Closing thought

To end things off, I don’t recommend people living with diabetes to consume energy drinks. Mainly due to the high-sugar intake of most drinks. The risk that the added herbal ingredients may also negatively affect medication taken is of great concern.

Caffeine is possibly less of the concern with energy drinks as people living with diabetes can still have high caffeine diets without including energy drinks. However, I would still recommend a safe daily caffeine intake of less than 300mg/day.

These findings are supported by the American Diabetes Association which advocates to avoid energy drinks and rather consume water, unsweetened herbal teas/coffee and milk.

Disclaimer: There is no conflict of interest with the author and any energy drink companies. The dietitian does not work for any companies and there was no payment received from any companies.


Jessica Pieterse is the director Dish Up Dietitians, Pieterse and Associates and also works at several private hospitals as a part-time locum dietitian, working in the ICU, medical and surgical wards. She has a special interest in nutrigemonics (DNA testing), critical care, weight loss, diabetes, hypercholesteromia, hypertension and gut disorders.

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