Abdominal -- and not peripheral -- obesity induces insulin resistance. Morbid obesity is not always accompanied by either diabetes mellitus or metabolic syndrome. Development of morbid obesity can require appropriate insulin secretion and recruitment of small insulin-sensitive adipocytes, able to store fatty acids. These fatty acids are therefore not stored in ectopic sites (muscle, liver, islets of Langerhans), and neither insulin resistance nor glucolipid toxicity develops and causes insulin deficiency. This explains the relative rarity of diabetes in morbid obesity. Patients with morbid obesity are at greater risk of developing mechanical complications (e.g. cardiac, pulmonary, or locomotor system, or sleep apnea) than metabolic complications or cardiovascular heart disease.