There is a high risk of a sharp rise in blood sugar after drinking coffee for breakfast.

Canadian researchers have found that drinking coffee before or during breakfast can lead to a sharp rise in blood sugar. The study showed that people who drank a cup of coffee before or during breakfast, even if they ate low-sugar cereals for breakfast, had a sharp rise in blood sugar levels, 250 percent higher than drinking decaf coffee.

Graham, who led the study, said caffeine causes the body to become resistant to insulin, which in turn increases blood sugar. However, he says this has no effect on ordinary healthy people because their bodies are able to cope with such changes in blood sugar. For ordinary people, coffee can be regarded as a healthy drink as long as they maintain a healthy lifestyle, exercise and a balanced diet, as well as weight control. In the past, studies have shown that long-term coffee consumption can also help reduce the risk of developing type 2 diabetes.

However, Graham advises people who already have type 2 diabetes and those at higher risk of diseases, including obese people, to avoid drinking coffee before or during breakfast, because it is already more difficult for their bodies to produce insulin. Caffeine also resists insulin, making it more difficult for their insulin to control blood sugar levels. For these two types of patients, it is best to drink decaffeinated coffee, even if they eat a sweeter cereal breakfast, which is more beneficial to their health.