Why does my morning black coffee spike my blood sugar?

It is incredibly frustrating to see a blood sugar spike from a drink that contains absolutely zero carbohydrates! The culprit here isn't hidden sugar; it is the caffeine.

Caffeine is a stimulant. When you consume it, it triggers your body to release stress hormones, primarily adrenaline and cortisol. As a defense mechanism, these hormones temporarily increase your body's insulin resistance. At the same time, they signal your liver to release stored glucose into your bloodstream to give you a quick boost of energy.

When you combine this caffeine response with the "Dawn Phenomenon" (your body's natural release of hormones to wake you up), it creates the perfect storm for a stubborn morning spike.

Many people with diabetes find that they actually have to take a small dose of rapid-acting insulin for their black coffee, just as if they had eaten a carbohydrate-heavy snack. If you use a pump, your doctor might also suggest adjusting your morning basal profile to counteract the caffeine. Keep in mind that everyone's caffeine sensitivity is different. It is best to track your numbers for a few days to see exactly how your body reacts before making any major adjustments to your insulin doses.