Bariatric Times - January 2009 - (Page 21)

Bariatric Times • January 2009 Metabolic Perspective 21 normal weight, and obesity. Each patient was studied after a 260kcal meal and after a 520kcal meal. Intact GLP-1 and total GLP-1 were measured. The total GLP-1 included the inactivated portion. GLP-1 has a 90-second half-life. The highest levels for intact GLP-1 were observed in the lean, healthy group, with an early sharp peak. The larger meal caused the highest rise and sustained level. The GLP-1 rise was less for the healthy obese subjects and those with T1D and T2D. The least rise after both meals occurred in the patients with T2D. These observations are supportive of impairment in initial gush, which is the stomach volume-controlled emptying that overflows the duodenum. It is important to note that the healthy obese subjects had almost the same impairment of GLP-1 secretion as the subjects with T2D. It is known from other studies that serum insulin levels rise with increasing body weight. It is only when the pancreas cannot meet the demand for insulin that diabetes is diagnosed. The diagnosis of diabetes should not be a requirement for treatment. Failure to show an adequate rise in GLP-1 with consequent high serum insulin level needs to be treated. Surgeons know that all patients with severe obesity are candidates for treatment. This increases the number of candidates with T2D in the United States from 23 million to 100 million. TREATMENT Surgeons have been treating T2D by exposing the ileum to glucose. The operations bypass the antro-duodenal-ileal control of gastric emptying, or shorten the distance to the ileum, so that glucose is not absorbed before it reaches the ileum. However, surgical operations eliminate the possibility of normal feedback control of GLP-1 secretion. Näslund observed very high plasma levels of GLP-1, 20 years following intestinal bypass.5 Valverde demonstrated with biliopancreatic diversion in nondiabetic obese patients a marked increase in plasma GLP-1 at one month, with further increase at three and six months.9 The peak levels were reached earlier after the meal at three and six months. The total GLP-1 secretion was markedly above normal after these operations. Continual excessive stimulation of the beta cells by GLP-1 may result in excessive insulin secretion even when blood glucose levels are normal or low. Service et al10 reported six patients with hyperinsulinemic hypoglycemia, requiring partial pancreatectomy, following Roux-enY gastric bypass (RYGB). There a focus on stomach surgery. Clarence Dennis, vice chairman of surgery, explained that he and Leo Rigler, chief of radiology, had studied patients with Wangensteen’s modification of Billroth II gastrectomy.6 They had observed fluoroscopically a portion of the standard meal appearing in the ileum within five minutes. Dennis recommended a small opening between the stomach pouch and jejunum so as to retard the rate of emptying of the pouch. The concern at the time was avoiding dumping syndrome. This is a marked reaction to hypertonic liquids and foods high in glucose. Patients complain of postprandial abdominal discomfort, weakness, sweating, diarrhea, and even a need to lie down. Dumping was considered an undesirable complication to be avoided. It now appears that mild, usually asymptomatic dumping occurs in healthy, normal-weight people. Schirra et al7 studied normal, lean humans and demonstrated that there is a threshold for glucose infused into the duodenum, above which plasma GLP-1 rises. When a 400mL solution containing 50 grams of glucose was infused over three hours, the concentration of glucose required to stimulate GLP-1 secretion was twice as high as was required if the glucose was given by mouth in 400mL of fluid in five minutes. Schirra showed that the duodenum dilutes stomach contents so that when they reach the jejunum there is no flush, but if the threshold of glucose entering the duodenum is exceeded either by rate of stomach emptying or concentration of the glucose, a small bowel flush results. Vilsboll et al8 showed that it is possible to modulate secretion of GLP-1 by meal size. Increasing meal size increases the number of “initial gushes.” The study compared the response of patients with T2D, T1D,

Table of Contents Feed for the Digital Edition of Bariatric Times - January 2009

Bariatric Times - January 2009 Surgical Perspective Psychological Perspective Metabolic Perspective Editorial Message Table of Contents Editorial Board Anesthesiology Perspective Body Contouring Perspective Journal Watch Advertiser Index News & Trends

Bariatric Times - January 2009

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.