In the video, a person discusses with their friend the considerations they need to take into account when determining their insulin dose and how much insulin they need to take for their upcoming meal. Video has English subtitles.
If you're on a multiple daily injections or pump therapy, you should always dose rapid-acting insulin when you eat carbohydrate-rich food or snacks. Exceptions include carb-loading for exercise, treating too low blood sugar, and small snacks (up to 10 grams of carbohydrates) for which you don't need to dose mealtime insulin.
The carbohydrate content of meal components is estimated to a precision of 5 grams (g), and if desired, the total carbohydrate amount for the meal can be rounded to the nearest ten. A rough visual estimation of the portion size is sufficient.
The need for mealtime insulin is expressed in units of rapid-acting insulin per 10 grams of carbohydrate. The amount is individual, typically ranging between ½–2 units / 10 g of carbohydrates. The need can vary throughout the day, typically being higher in the morning and late morning and decreasing towards the evening.