Insulin Resistance Linked to Diet

Dr. Alfonso Torquati was quoted as saying, “We think that bariatric surgery is metabolic. It bypasses the duodenum and changes the way that glucose and lipid metabolism work” (“Gastric Bypass Halves Framingham Risk Score,” March 2007, p. 32).

He says later in the article that the same changes in insulin resistance improvement are not seen with gastric banding, again suggesting that the metabolic changes are somehow linked to duodenal bypass.

I would suggest that if Dr. Torquati were to evaluate the metabolic changes that occur within the first week of beginning a strict rice diet, he would appreciate a drop in insulin resistance, and the ability to stop most oral hypoglycemics within that time frame. It is therefore not intuitive to conclude that duodenal bypass has anything to do with decreasing insulin resistance.

It is more likely that the bypass patients are severely restricted in what they can and do eat in the immediate postoperative period. Gastric banding limits oral intake to a lesser degree, and patients can still eat some of the same foods they had eaten preoperatively, only in smaller portions.

Douglas Jay Sprung, M.D.

Maitland, Fla.

Dr. Torquati replies:

We thank Dr. Sprung for highlighting the importance of caloric restriction in the management of type 2 diabetes. We agree that any intervention that limits the daily amount of calories results in decreased insulin resistance. However, more important is the magnitude of change in insulin sensitivity and maintaining this effect over time. There is much evidence that gastric bypass surgery induces and maintains the greatest change in insulin sensitivity in individuals with class II and III obesity. In our recent trial we observed 12 months after gastric bypass a decrease in hemoglobin A1c of 1.7 ± 1.1% from baseline (J. Gastrointest. Surg. 2005;9:1112–6 and 1117–8). Another study showed a reduction in HbA1c of 0.6 ± 0.3 % after 12 months of combined therapy with sibutramine and a low-calorie diet similar to a post-gastric bypass regimen (900–1,300 kcal daily) (Diabetes Care 2003;26:2505–11).

What are the reasons for this significant difference? We think that a restrictive procedure such as the gastric bypass that limits caloric intake and has a malabsorptive component is the most effective treatment for subjects with type 2 diabetes and class II and III obesity. There is evidence that bypassing the duodenum and the proximal jejunum in addition to caloric restriction decreases insulin resistance more than does a simple restrictive procedure (i.e., gastric banding). A study of meal-stimulated responses of insulin, ghrelin, peptide YY, glucagon-like-peptide-1, and pancreatic polypeptide in humans and rodents following different bariatric surgical techniques found that gastric bypass patients had early and exaggerated insulin responses, potentially mediating the improved glycemic control in patients with diabetes (Ann. Surg. 2006;243:108–14). None of these effects were observed in patients losing similar weight through gastric banding, suggesting that the hormonal changes are not secondary to weight loss alone.

This evidence and more, omitted for the sake of brevity, shows that the duodenal-jejunal bypass component of the gastric bypass is a major contributor to the improvement and resolution of obesity-related comorbidities observed after gastric bypass surgery.

Health Insurance According to Need

Dr. Kevin Grumbach would have us emulate the Canadian health system, but fails to list the long waits for most surgeries and imaging studies—waits which most U.S. citizens would find unacceptable (“What is the best way to reform the U.S. health care system?” Point/Counterpoint, December 2006, p. 28).

Indeed, the numbers of Canadians who avoid the wait by obtaining care in the United States is impressive, but that factor also is ignored by Dr. Grumbach.

Dr. Robert Moffit's views are pertinent and accurate. In addition, we need to recognize that the “mandates” imposed by a majority of states make the cost of individual health insurance policies excessively high; therefore, this is a significant cause of many going uninsured. Health insurance policies should be like homeowners' policies, where the buyer contracts for the type of coverage that is needed and affordable. Mandates primarily are a response to demands by special interest groups who benefit from forcing the buyers of policies to include what they may neither need nor want and often cannot afford.

A federal law that would allow national sales of health insurance, like national sales of life insurance, would help, as would a federal law that would require that states accepting federal Medicaid funds be prohibited from forcing mandated benefits on private buyers of health insurance policies.

Alan W. Feld, M.D.


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