Ready, Set, Stop!
Preventing diabetes before it starts
Before someone is diagnosed with type 2 diabetes, he or she is already on a slippery slope called pre-diabetes. Sound grim? Well, there's an upside: Even though most people with pre-diabetes go on to develop diabetes within 10 years, a body of evidence is emerging that shows a person with pre-diabetes can make a U-turn--through lifestyle changes or medication--and may never have to become a person with diabetes.
How do you know you have pre-diabetes? The same way regular diabetes is diagnosed: by having your blood glucose measured. In pre-diabetes, blood glucose runs higher than normal, but not high enough to be classified as diabetes. (See table below.) And as with uncontrolled diabetes, pre-diabetes blood glucose levels can continue to rise without careful management. There are two types of glucose tests recommended by the American Diabetes Association to diagnose pre-diabetes: the fasting plasma glucose (FPG) test and the oral glucose tolerance test (OGTT). The FPG blood test is taken after an 8-hour fast, while the OGTT blood test is taken after consuming a special glucose drink (following an 8-hour fast).
Pre-diabetes can be considered impaired fasting glucose (IFG), impaired glucose tolerance (IGT), or both. Either an FPG between 100 mg/dl and 126 mg/dl or an OGTT between 140 mg/dl and 200 mg/dl would indicate a person has pre-diabetes. Blood glucose levels above these ranges mean a diagnosis of diabetes; below these ranges is considered normal, although levels that approach the pre-diabetes lower limit shouldn't be ignored.
In addition to being a risk factor for diabetes, pre-diabetes also increases one's chances for other health problems. Glucose levels within the pre-diabetes range confer a greater likelihood of cardiovascular disease, although to a lesser extent than diabetes. Recent research has also shown that rates of retinopathy--diabetic eye disease that can cause blindness--are higher for those with blood glucoses within the pre-diabetes range than for the general population.
What is going on here? As hard as scientists and doctors try to define conditions using the best available data, diseases don't necessarily obey the rigid cutoffs researchers set. This is especially true in the case of diabetes and pre-diabetes. Considering recent data on cardiovascular disease and retinopathy, pre-diabetes seems less like a unique condition and more like a less severe diabetes. A panel of experts is currently addressing this issue.
Sending Pre-Diabetes Packing
With diabetes numbers on the rise, researchers are working hard to find effective ways to keep pre-diabetes from turning into full-blown diabetes. The usual suspects--diet and exercise--are proving valuable at staving off diabetes, but certain diabetes medications are also showing promise as agents of prevention.
The Diabetes Prevention Program (DPP) compared lifestyle and the diabetes medication metformin head to head in patients with pre-diabetes to determine what method better retards diabetes development. The subjects--generally obese and with an average age of 51--were put into 3 groups: an intensive lifestyle intervention group (that received intensive motivational therapy, ate less fat and fewer calories, and exercised 150 minutes per week), a group that took metformin and received information about lifestyle changes, and a group that received a placebo along with the lifestyle information. The winner was intensive lifestyle changes, which reduced diabetes development by 58 percent compared to placebo, followed by metformin, which reduced diabetes development by 31 percent relative to placebo.
In the DPP trial and another study from Finland, researchers found that even modest increases in activity, like walking 150 minutes a week, and weight loss of as little as 5 to 7 percent could delay or prevent diabetes. However, these small changes came from huge efforts on the part of patients and specially trained staff. Since this level of guidance isn't available to most people, it's unclear whether such lifestyle modification is a viable public health strategy for curtailing rising diabetes rates.
Several other studies have been conducted to ascertain what benefits other diabetes medications might hold for populations with pre-diabetes. Tests on the alpha-glucosidase inhibitor acarbose showed it reduced conversion to diabetes from pre-diabetes by 56 percent relative to placebo. A recent study presented at the 2008 Scientific Sessions of the American Diabetes Association found that the thiazolidinedione drug pioglitazone (Actos) lowered the progression to diabetes by 81 percent over 3 years relative to placebo. However, it should be noted that no drugs have yet been approved for the treatment of pre-diabetes.
What's clear is that pre-diabetes may be reversible if certain measures are taken. Therefore, screening is extremely important to find those at greatest risk. According to a recent report by the U.S. Centers for Disease Control and Prevention (CDC), 25 percent of Americans have pre-diabetes; a separate CDC survey found that 46 percent of those between the ages of 40 and 74 have it. More troubling still, only 4 percent of adults know they have it. Which makes getting information about how pre-diabetes is diagnosed and treated even more crucial. So pass it on.