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Diabetes is considered by many to be an epidemic in the United States.
It is a particularly devastating disease among the native American
populations. The prevalence, increasing incidence, associated mortality
and morbidity all point to diabetes as one of the most serious health
challenges facing us.
There are two main forms of diabetes. Type
1 diabetes is due primarily to autoimmune-mediated destruction of
pancreatic beta-cell islets, resulting in absolute insulin deficiency.
People with type 1 diabetes must take exogenous insulin for survival to
prevent the development of ketoacidosis. Its frequency is low relative
to type 2 diabetes, which accounts for over 90% of cases globally. Type
2 diabetes is characterized by insulin resistance and/or abnormal
insulin secretion, either of which may predominate. People with type 2
diabetes are not dependent on exogenous insulin, but may require it for
control of blood glucose levels if this is not achieved with diet alone
or with oral hypoglycemic agents.
Diabetes mellitus affects more than 6% of the US population, with the
great majority having type 2 diabetes mellitus (DM). In some older
groups, the prevalence of DM and its metabolic forerunner, impaired
glucose tolerance (IGT), approaches 25%. Throughout the past decade,
1990 to 1998, diagnosed diabetes rose 33 percent (4.9 percent to 6.5
percent) among U.S. adults. A follow-up study by the CDC showed that in
1999 alone, increases in diabetes were noted in every category examined
including sex, age, race, education, weight and smoking status.
Prevalence increased among both women (7.4 percent to 7.6 percent) and
men (5.5 percent to 6.0 percent) and among all ethnic groups including
whites (5.9 percent to 6.2 percent), blacks (8.9 percent to 9.9
percent), Hispanics (7.7 percent to 8.0 percent) and all others (6.6
percent to 7.7 percent). Approximately 800,000 new cases of diabetes are
diagnosed each year. It is the seventh leading cause of death in this
country and a major contributor to serious health problems such as heart
disease, stroke, blindness, high blood pressure, kidney disease, and
amputations. When the long-term complications of this disease and their
costs are considered, the implications of these statistics are sobering.
The importance of blood glucose control in preventing microvascular
complications of DM, such as retinopathy and nephropathy, is now
recognized. The American Diabetes Association's recommended targets for
glycemic control include a preprandial blood glucose level of 80 to 120
mg/dL (4.4 to 6.7 mmol/L), a bedtime blood glucose level of 100 to 140
mg/dL (5.6 to 7.8 mmol/L), and an HbA1c level of less than 7%. More
stringent guidelines have recently been offered by the American College
of Endocrinology and the American Association of Clinical
Endocrinologists: preprandial blood glucose levels less than 110 mg/dL
(6.1 mmol/L), 2-hour postprandial glucose levels less than 140 mg/dL
(7.8 mmol/L), and HbA1c levels at 6.5%. These recommendations are based
on findings from 3 landmark studies: the Diabetes Control and
Complications Trial, the Kumamoto Study, and the United Kingdom
Prospective Diabetes Study (UKPDS), which have shown unequivocally that
maintaining blood glucose concentrations as close to normal as possible
in both type 1 and type 2 DM decreases the incidence of microvascular
complications. Whether such a relationship exists for macrovascular
complications, such as myocardial infarction and stroke, is less clear.
About thirty percent of patients with insulin- or non-insulin-dependent
diabetes have delayed gastric emptying (diabetic gastroparesis). Some of
them complain of epigastric pain, nausea, vomiting or postprandial
fullness (diabetic dyspepsia), although only a minority are severely
symptomatic. The clinical situation is further complicated by the
overlap of symptoms of gastroparesis with those of functional bowel
disorders, such as nonulcer dyspepsia (NUD) and irritable bowel syndrome
(IBS).
Diabetic gastroparesis is clinically relevant not only by virtue of the
symptoms induced but also because it may contribute to inadequate
glycemic control and impaired absorption of orally administered drugs.
Recent data suggest that abnormal blood glucose control, not only
autonomic neuropathy, contribute to the pathogenesis of disordered
gastric motility. In most cases, diabetic gastroparesis is diagnosed
clinically in the absence of demonstrable lesions of the upper
gastrointestinal tract.
The “gold standard” method of measuring gastric emptying time is
scintigraphy. A solid or semi-solid meal may be used. This technique
allows normal feedback regulation to occur during the test period. A
blood glucose concentration should be obtained at the time of the test.
The test involves the exposure to a radiation dose. The use of
scintigraphy is very expensive (about $1,000 per evaluation) and
consequently the clinical use is rare. The combination of expense and
radiation exposure makes this test impractical for the serial assessment
of gastric performance.
MED Foundation is supporting research in cooperation with the Western
Research Company (a company with a long history of successful projects
funded by the National Institutes of Health from Tucson Arizona) in the
development of an economical, noninvasive test for the evaluation and
diagnosis of gastroparesis. The goal is to develop a test that is
practical and affordable that can then be accessible to all diabetic
sufferers.
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