The American Diabetes Association explains that a patient with impaired glucose tolerance has the condition known as pre-diabetes: His blood sugar levels are abnormally high, but are too low for a diabetes diagnosis. Impaired glucose tolerance is diagnosed using the oral glucose tolerance test. During this test, a patient's blood sugar is measured first after fasting and then two hours after drinking a sugar-rich drink. A blood sugar level between 140-199 milligrams per deciliter at the two-hour mark means that the patient has impaired glucose tolerance. Fortunately, progression to diabetes may be delayed or prevented with lifestyle changes or medication.
Engaging in Moderate-Intensity Exercise
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) summarizes a large body of literature on diabetes prevention, and informs readers that a modest amount of exercise, done consistently, can help in preventing the progression of pre-diabetes to Type 2 diabetes. One especially significant study, known as the Diabetes Prevention program, was a landmark study in that it showed that patients at risk for developing Type 2 diabetes can prevent or at least delay the onset of the condition by making changes to their daily lives. The study included over 3,000 patients, and found that being moderately physically active for 150 minutes weekly -- for instance, walking briskly for 30 minutes, five times a week -- can help contribute to modest weight loss, which in turn can significantly decrease the risk of pre-diabetes becoming Type 2 diabetes.
Eating a Low-Calorie, Low-Fat Diet
The Diabetes Prevention Program study also included another component in its "lifestyle modification" group of subjects: eating a healthy, well-balanced diet. In the landmark study, a patient in the lifestyle modification group decreased his caloric intake by an average of 450 calories daily and his fat intake by an average of nearly 7 percent. These changes to the diet, combined with the consistent, moderate level of exercise, resulted in a modest but important weight loss: By losing between 5 and 7 percent of his body weight -- in a 200-pound person this is equivalent to a little over 10 pounds -- the patient was able to decrease his risk of Type 2 diabetes by 58 percent. This is a significant result, as it shows that patients with pre-diabetes can delay or even prevent the onset of Type 2 diabetes without having to rely on medications.
Taking the Medication Metformin
Metformin is a medication that is often considered to be "first line," or first choice, treatment for type 2 diabetes. If you have developed Type 2 diabetes this means you are no longer sensitive to the insulin your body makes: Rather than glucose going into the cells of the body, it accumulates within the bloodstream, leading to abnormally high levels of sugar in the blood. As described in the medical reference UpToDate, metformin works in two main ways: It decreases the amount of sugar that is produced by the liver, and increases the body's sensitivity to insulin. For patients who are at risk for developing Type 2 diabetes -- that is, they have pre-diabetes and are either unable or unwilling to make the lifestyle modifications needed to normalize their blood sugar levels -- metformin may be beneficial. The Diabetes Prevention Program study found that a patient who was placed in the "metformin intervention" group was able to reduce her risk of Type 2 diabetes by 31 percent. The disadvantage that patients with impaired glucose tolerance have to consider is that, like all medications, metformin has potential side effects. According to UpToDate, these commonly include diarrhea, nausea and vomiting; less commonly, patients may experience rashes, chest discomfort, weakness or headaches. So patients with impaired glucose tolerance must weigh the potential benefit of metformin against the risk of side effects. If possible, it is generally preferable to start with lifestyle modification before beginning a pharmacological intervention.
References
- American Diabetes Association: Prediabetes FAQs
- NIDDK: Diabetes Overview
- New England Journal of Medicine; Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin; W.C. Knowler et. al.; February 2002
- UpToDate; Metformin: Drug Information; Lexi-Comp, Inc.; 2010
