Diabetes is a multisystem disorder caused by a relative or absolute lack of insulin. The prevalence of diabetes is approximately 7%. The majority (85%) have type 2 diabetes. With increasing obesity, reduced exercise and alterations in dietary habits, the prevalence of diabetes is increasing. For every case of diagnosed type 2 diabetes, there is another undiagnosed individual.
The cleaving of proinsulin from the beta cells of the pancreas produces the peptide hormone insulin. Insulin has both excitatory and inhibitory effects. For example, it simultaneously stimulates lipogenesis from glucose whilst inhibiting lipolysis. It is the inhibitory actions, such as the tonic inhibition of lipolysis, proteolysis, glyogenolysis, gluconeogenesis and ketogenesis, that are the physiologically more important.
Thus, the fasting hyperglycaemia of diabetes is due predominantly to overproduction of glucose by the liver as opposed to the commonly thought, underutilisation of glucose by peripheral tissues. In effect, insulin "keeps the brakes on" a number of key metabolic processes and prevents over-secretion of the "anti-insulin" hormones -glucagon, cortisol, growth hormone and catecholamines. These hormones also happen to be released as part of the "stress response" to surgery.
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Anaesthesia and Diabetes Mellitus
