Pilot Study for an Oral Insulin Sensitivity Test And Effects of Vinegar on Glucose Absorption
Principal Investigator: Arline D. Salbe, PhD
Co-investigators: S. Mitchell Harman, MD, PhD; Panayiotis D. Tsitouras, MD; Frank Gucciardo, PA; Carol Johnston, PhD
In 2005, 20.8 million people in the U.S. were estimated to have diabetes, representing 7% of the population; 21% of the population over 60 has diabetes. As many as one third of all individuals are unaware of their diagnosis. Although diabetes was listed as the sixth leading cause of death in 2002, research has shown that people with diabetes have twice the risk of death as similarly aged people without diabetes. In 2000, the worldwide prevalence of diabetes was estimated at 171 million people, a figure expected to more than double by 2030.
More than 90% of diabetes cases are type 2 diabetes mellitus, which is associated with obesity and aging. Serious complications include blindness, kidney failure, neuropathy, atherosclerosis leading to heart disease, and amputations. Pathologic factors include resistance to insulin action and a defect of the insulin secreting cells resulting in a lack of compensation for insulin resistance. Glucose intolerance and hyperglycemia are characteristic symptoms. Simple but effective ways to lower blood glucose levels, applicable to a wide variety of dietary habits, are strongly needed. Common household vinegar may do just that. Several studies in both animals and humans indicate that vinegar has potent glucose-lowering effects. However, the mechanism of action remains in question and understanding the way vinegar lowers blood sugar is critical to making effective recommendations for its use.
Mechanisms that have been proposed for the effect of vinegar on glycemia include interference with digestion of complex carbohydrate; delayed gastric emptying; enhanced uptake of peripheral glucose and conversion to glycogen; and increased satiety. The aim of this proposed pilot study is to explore the mechanism of the glucose lowering effects of vinegar by examining the rate of absorption of glucose from the digestive tract. If vinegar decreases the rate of glucose absorption into the blood after a meal, then adding it at mealtimes to decrease the rise in post-prandial glucose might be recommended. If vinegar affects glucose metabolism in the liver, then consuming it at bedtime might be recommended to decrease the pre-meal rise in blood sugar known as the 'dawn phenomenon'. This study will also characterize the safety and reproducibility of a novel method for estimating the glucose absorption rate. Validating this simple method of glucose metabolism will, in itself, be an important addition to the assessment procedures used in diabetes research.
| Status: |
IRB Approved; Funding applications submitted |
| Procedures: |
At baseline, study participants will give informed consent and be screened by medical history, physical exam, and standard laboratory tests. Each participant will have four study visits at one-week intervals. In randomized order, participants will be given placebo twice (60 ml water, 1tsp saccharine, 1 drop color) and vinegar twice (20 ml vinegar = 1 g acetic acid, 58 ml water, 1 tsp saccharine, 1 drop color), followed immediately by a light meal. Testing for glucose absorption using the oral octreotide/insulin suppression test will take place over a 3-hour period, with blood samples drawn every 20 minutes. Before the test meal, forearm veins will be cannulated bilaterally. One arm will be infused with 0.9% saline for blood sampling. At time zero, a 25 g intravenous bolus of Octreotide (Sandostatin®) will be given and the opposite arm infused via a digital peristaltic pump with a 0.9% NaCl sterile solution to deliver 5 mU/m2/min regular human insulin and 0.5µg/min octreotide. Samples will be frozen until assayed for glucose and insulin. During testing, participants will rate their hunger and satiety levels by responding to a questionnaire. The effects of vinegar on both the rate of rise in glucose concentration and on vinegar-induced satiety will be estimated using established statistical methods. |
|