Surgery has major effects on carbohydrate metabolism and thus presents special risks for patients with diabetes. Surgical mortality rates for patients with diabetes have declined but the successful perioperative care of these patients requires close cooperation between surgeons, anesthesiologists, and primary physicians to prevent complications. More than 20 million people in the USA have diabetes and at least half of them will require surgery at some point in their lives. In addition to surgical conditions typical of the general population, patients with diabetes experience increased intervention for occlusive vascular disease; cholelithiasis; ophthalmic disease (i.e., cataract extraction, vitrectomy); renal disease; and infection. Three of four patients with diabetes are older than 40 years and are approaching a time of life when surgical indications increase. The presence of diabetes typically is known before operation, although a new diagnosis of diabetes is made in the perioperative period in as many as 20% of cases.

Pathophysiology

The endocrine pancreas, which consists of the islets of Langerhans, accounts for less than 3% of the total pancreatic mass in adults. The islets are unevenly distributed through the pancreas and contain four cell types: A (α) cells, which secrete glucagons; B (β) cells, which secrete insulin; D (δ) cells, which secrete somatostatin; and F cells, which secrete pancreatic polypeptide. Insulin, the major secretory product, is synthesized as a precursor molecule, preproinsulin, in the endoplasmic reticulum and is cleaved by microsomal enzymes to proinsulin. Proinsulin is then converted by proteolysis to insulin and an amino acid residue, c-peptide.