To confirm the diagnosis of acromegaly a physician orders - IGF (Insulin-like Growth Factor) test: Growth hormone is the culprit behind acromegaly. When growth hormone enters liver it produces IGF which in-turn signals the synthesis of muscles, bones and cartilages. - OGTT (Oral Glucose Tolerance Test): IGF also alters the response of body towards glucose and insulin functioning. This test confirms the action of IGF in body.