Glucose

Glucose is a simple sugar and the most common monosaccharide found in nature. With the formula C6H12O6, it serves as a primary fuel for cells and is widely used in sports drinks and energy supplements.

Explanation

As a single-unit carbohydrate, glucose is readily digested and absorbed in the small intestine via the sodium‑glucose cotransporter SGLT1. Once in the bloodstream it is taken up by tissues and oxidised to produce ATP. Because of its rapid absorption and high glycaemic index, glucose provides quick energy during exercise and helps maintain blood glucose levels when consumed in a beverage. Sports nutrition products often include glucose alone or in the form of polymers such as maltodextrin to deliver carbohydrate without excessive sweetness. However, the intestine can only absorb about 60 g of glucose per hour before SGLT1 becomes saturated, which is why blending glucose with other sugars can increase total carbohydrate uptake. Consuming large amounts of glucose without sufficient water can lead to hypertonic solutions that slow gastric emptying.

Role of glucose in sports drinks

A typical endurance beverage contains 4–8 % carbohydrate, much of which comes from glucose or its derivatives. For example, a drink with 6 % glucose provides 6 g per 100 mL, supplying fast energy during long runs or rides. Glucose powders are also sold for mixing custom drinks; combining them with a small amount of fructose (at a 2:1 ratio) can boost absorption and reduce gastrointestinal discomfort. Because glucose has a high osmotic effect, sports drinks balance it with water and electrolytes to keep osmolality near that of blood. Overly concentrated solutions, such as undiluted syrups or gels, can cause stomach cramps or diarrhoea unless consumed with additional water. Understanding how glucose behaves helps athletes choose and mix drinks that deliver immediate energy without compromising hydration.

Glucose remains the benchmark carbohydrate for rapid energy in sports nutrition due to its simple structure and efficient absorption.

Related Terms: Fructose, Sucrose, Maltodextrin, Dextrose, Carbohydrate concentration