When you have diabetes, your body either doesn't produce enough insulin or can't use it effectively. Insulin is a hormone that helps regulate blood sugar levels. Without it, your body can't process glucose properly, leading to high blood sugar levels. There are two main types of diabetes: type 1, where the pancreas doesn't produce insulin, and type 2, where the body can't use insulin properly. Insulin injections are necessary for managing both types. The insulin sensitivity factor (ISF) is a measure of how much one unit of insulin will lower your blood sugar level, measured in milligrams per deciliter (mg/dL). Knowing your ISF helps you determine the correct dose of insulin to take, especially for short-acting or rapid-acting insulin. If you take too much insulin, your blood sugar can drop too low, causing hypoglycemia, which is dangerous and can lead to seizures or loss of consciousness. If you take too little, your blood sugar remains high, leading to hyperglycemia, which can cause long-term complications. Insulin sensitivity varies from person to person and can change throughout the day due to factors like activity level and hormone secretion. There are two main methods to calculate your ISF: the 1500 rule for regular insulin and the 1800 rule for short-acting insulin. For regular insulin, divide 1500 by your total daily dose of insulin. For example, if you take 30 units daily, your ISF is 1:50, meaning one unit of insulin lowers your blood sugar by 50 mg/dL. For short-acting insulin, divide 1800 by your total daily dose. If you take 30 units daily, your ISF is 1:60, meaning one unit lowers your blood sugar by 60 mg/dL. It's important to test your ISF at the right time for accurate results, and consult your doctor for personalized advice.