Diet coke (1 piece)

Confirm the pattern by repeating the same test on separate days: drink the same amount of Diet Coke under similar conditions and compare it with plain water. Sensor lag, stress, exercise, and recent meals can create apparent rises.

Try caffeine-free Diet Coke or a non-caffeinated, unsweetened sparkling water. Caffeine can raise glucose in some people by increasing stress-hormone activity.

Avoid drinking it on an empty stomach if that is when you notice the largest response. Have it with a balanced meal or snack containing protein and fiber, such as plain Greek yogurt with berries or a small handful of nuts.

Keep the serving smaller and sip it slowly rather than drinking a large amount quickly; assess whether your response differs with a can versus a larger bottle.

Take an easy 10–20 minute walk after drinking it or after the accompanying meal, if safe for you; light movement often reduces post-meal glucose rises.

Review your results with a clinician if spikes are frequent, large, or accompanied by symptoms, especially if you use glucose-lowering medication.