Insulin levels are used in the diagnosis of insulinomas. Measures of insulin levels and glucose levels by simple blood tests should show an excess insulin level (>30µ/ml) and a decreased glucose level (normal range being between 65 and 95 mg/dl). This is best represented as a ratio of insulin to glucose (I-G ratio). In affected individuals this ratio is generally >1.0 where normally it is less 0.4. Ideally, the sample should be taken during a hypoglycaemic episode, but due to the fact that most patients have intermittent occurrences, this is usually not possible.