الفهرس 
Pathophysiology Of Type II DiabetesOnly 14 pages are availabe for public view
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Abstract
Diabetes Mellitus is a major health problem, there are 2 types of diabetes, type 1 (insulin-dependent) and type 2 (non–insulin-dependent).
Type 2 diabetes mellitus is a common disease with numerous complications. Bariatric surgery is an efficient procedure for controlling T2DM in morbidly obese patients.
Risk factors for type 2 diabetes can be classified as modifiable including: Obesity, Central obesity, Lack of physical activity, Smoking, Alcohol abstinence, Low fiber in the diet, High saturated fat in the diet and nonmodifiable including: Ethnicity, Age, Genetic factors, Family history of type 2diabetes, Prior gestational diabetes, Prior glucose intolerance, History of cardiovascular disease, History of hypertension, History of dyslipidemia, Low birth weigh.
The pathogenetic mechanisms underlying type 2 diabetes are insulin resistance and deficiency in insulin secretion (Beta-Cell Dysfunction) and genetic factors and the effect of gut hormones.
Insulin resistance mechanisms include insulin receptors level (cellular mechanisms) and role of adipocyte products, and impaired bioenergetic capacity of skeletal muscle mitochondria.
Insulin secretion deficiency mechanisms include glucose toxicity and Lipotoxicity meaning prolonged exposure of insulin secreting cells to elevated levels of hyperglycemia or fatty acids lead to cellular dysfunction or by deposition of protein in the islets of Langerhans in the pancreas (islet amyloid).
The role of Genetic Factors is by two methods, the so-called candidate gene approach and the genome wide scan approach and includes many studies of many genes like: Coactivator-1α, Peroxisome proliferator activated receptors Gamma, Hepatocyte Nuclear Factor 4 α, KCNJ11 Calpain-10, ENPP1 TCF7L2.
The role of gut hormones in pathophysiology of Type 2 diabetes is through its role in the digestion, absorption, and assimilation of ingested nutrients, signals from the gastrointestinal tract are important regulators of gut motility and satiety and the most important gut hormones in regulating Type 2 diabetes mellitus are: GIP, GLP-1, Cholecystokinin and Ghrelin.
Carbohydrates are classified into monosaccharides, disaccharides, oligosaccharides and polysaccharides.
Digestion of carbohydrates occurs in the mouth then in the duodenum then in the intestine resulting in monosaccharides.
Absorption of carbohydrates occurs across the intestinal epithelial cells into the blood by facilitated diffusion and by Na-dependent facilitated transport resulting in glucose.
Glucose is used in glycolysis, Krebs cycle, pentose phosphate pathway, synthesis of glycogen, synthesis of amino acids, and synthesis of acetyl-CoA which is the precursor of fatty acids and cholesterol
The maintenance of a stable level of glucose in the blood is regulated by homeostatic mechanisms, involving the liver, extrahepatic tissues, and several hormones.
The surgical treatment of morbid obesity has developed into a subspecialty of general surgery and is known as bariatric surgery which is recommended in persons with a body-mass index of more than 40 or of more than 35 in patients with coexisting illnesses only if other forms of treatment had failed.
Bariatric operations have traditionally been divided into three groups: restrictive, malabsorptive, and mixed.
Several studies show that most of these patients are able to discontinue medications and maintain normal serum glucose levels following surgery induced weight loss.
Roux-en-Y gastric bypass (RYGBP) is one of the most common forms of bariatric surgery. This procedure restricts stomach volume through creation of a small pouch along the lesser curvature and reroutes nutrient flow from the upper portion of the stomach into the mid- to distal jejunum. Consequentially, most of the stomach, the duodenum, and proximal jejunum are bypassed; the operation can be done by laparoscope.
Complications of Roux-en-Y gastric bypass include: anastomotic leak with peritonitis, acute distal gastric dilatation, Roux limb obstruction, severe wound infection, minor wound infection or seroma, venous thrombosis, stomal stenosis, marginal ulcer, intestinal obstruction, internal hernia, staple line disruption, incisional hernia, cholecystitis, deficiencies of vitamin B12, Iron deficiencie and anemia.
Jejunoileal Bypass entailed excluding most of the small bowel, by leaving just 30 cm of the jejunum and 10 cm of the ileum in continuity.
Although weight loss was dramatic the jejunoileal bypass essentially ceased to be performed because of its complications
The sleeve gastrectomy is a restrictive procedure.
Ileal transposition involves the removal of a small segment of the ileum with its vascular and nervous supply and inserting it into the proximal small intestine.
Other surgical procedures include horizontal gastroplasty, vertical banded gastroplasty and biliopancreatic bypass.
Most patients who undergo bariatric surgery experience rapid resolution of type 2 diabetes, Improvement of T2DM after gastrointestinal surgery has been reported in patients with relatively mild forms of obesity and in nonobese individuals, Most reported series show that return to euglycemia and normal insulin levels occur within days after surgery, long before there is any significant weight loss.
The term hindgut hypothesis has been used to describe the effects of some bariatric operations result meaning enhanced nutrient delivery to the distal intestine, accentuating L-cell secretion of anorexigenic and antidiabetic peptides.
Foregut Hypothesis posits that exclusion of a short segment of proximal small intestine from contact with ingested nutrients exerts direct antidiabetes effects.
Other proposed mechanisms of T2DM resolution after surgeries include changes in gut motility and gastric emptying.