What does it mean if the line goes straight up?

That your blood glucose level is going up rapidly, also called a spike.

A rapid increase in blood glucose is known as a spike. If you see this happening it means that there has been a sudden release of a lot of glucose into your system. This can happen for a number of reasons:

  • Eating food with a high carbohydrate content - if the spike is very rapid it probably means simple carbs like sugar

  • A sudden stress event - a near-miss on the drive to work or a stressful meeting can cause your body to release glucose from your stored energy

  • An extremely hot or cold, shower - as for the stress event, your body will release glucose to deal with the cold or heat

  • Exercise - as your body responds to the increase in movement it will release glucose for energy

The spikes you need to avoid are those related to food as they will interrupt your progress towards weight loss.