Final answer:
Critical blood glucose levels fall under the severe range and indicate a possible medical emergency. They are significantly lower (hypoglycemia) or higher (hyperglycemia) than the normal fasting range of 70-130 mg/dL.
Step-by-step explanation:
Blood glucose results that appear as CRITICAL, either low or high, do not fall within the normal range or even the moderate range. They would be classified as severe range. A normal fasting blood glucose level is between 70-130 mg/dL, and post-prandial levels after a meal typically range from 100-140 mg/dL. Blood glucose levels that are significantly lower than the normal fasting range can indicate hypoglycemia, which is critically low. On the other hand, levels that stay well above the normal range, particularly after fasting (such as above 125 mg/dL), suggest hyperglycemia or diabetes, which are critically high conditions. Thus, critical blood glucose levels are those that are much lower or higher than what is considered normal or safe and can signal a medical emergency.