Methods and devices involving using a bolus calculator to account for an uncertainty of a carbohydrate estimate to reduce a risk of hypoglycemia and/or a risk of hyperglycemia. More specifically, methods and devices using an algorithm executed by a processor of the bolus calculator and using a carbohydrate estimate and a measure defining the uncertainty of the carbohydrate estimate to determine the probability of hypoglycemia and/or hyperglycemia if the carbohydrate estimate is an overestimate or an underestimate, and subsequently providing recommendations and alerts to a user.