The American Diabetes Association (ADA) revises its Clinical Practice Recommendations yearly, and the 2008 version includes more changes than usual. Besides several substantive additions, there was an effort to streamline the document, “to pare down recommendations to focus on primary treatments that are known to benefit people with diabetes,” says Sue Kirkman, MD, vice president of clinical affairs for the association.
A broader approach to weight control is perhaps the most striking change in policy, but sections on screening, hypoglycemia, and the treatment of older adults should be of particular interest to primary-care physicians as well, she says.
Expanding the diet options
As was the case in earlier versions, weight loss is a key recommendation for overweight individuals who have or who are at risk of diabetes. But the 2008 guidelines note that “either low-carbohydrate or low-fat calorie-restricted diets may be effective in the short term (up to one year).” Previously the ADA did not recommend low-carbohydrate diets because of insufficient data documenting their safety and efficacy.
“Obesity is a big problem, and many studies show that adherence to a diet is the most important determinant of weight loss, not which diet it is,” Dr. Kirkman observes. “Different people adhere to different diets. A lot of clinical trials have shown at least equivalent weight loss with low-carb diets…it didn't seem reasonable to advise against one strategy.”
Because individuals on low-carbohydrate diets are likely to increase intake of other macronutrients, the Recommendations also advocate monitoring of lipid profiles, renal function, and (in the presence of nephropathy) protein intake.
Testing and prevention
Screening criteria and preventive strategies are more explicit. The new guidelines recommend diabetes and prediabetes testing for asymptomatic individuals who are overweight and have additional risk factors (e.g., physical inactivity, family history of diabetes, hypertension), regardless of age. As before, all individuals older than 45 should also be screened.
The section on prevention and delay of type 2 diabetes now includes a table listing interventions and summarizing prevention trial results. (Interventions with documented efficacy are presented in the table below.) Counseling is recommended for patients with impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) to help them achieve the goals established by the multicenter Diabetes Prevention Program (DPP): weight loss 5%-10% of body weight and physical activity equal to 150 minutes weekly of moderate walking.
A more significant change is the addition of pharmacotherapy for prevention. The guidelines recommend that clinicians consider metformin for individuals who are obese, younger than 60 years old, and at very high risk (i.e., both IFG and IGT and at least one other risk factor). Metformin was chosen for its low cost (the drug is available generically), relatively benign side-effect profile, and performance in the DPP.
Approach to treatment
The guidelines now include treatment recommendations—general strategies rather than specific drugs—for type 1 as well as type 2 diabetes. For type 1 diabetes, the emphasis is on the use of multiple injections with a mix of basal and prandial insulin, the latter to match carbohydrate intake, premeal blood glucose, and anticipated activity. Insulin analogs should be considered, particularly if hypoglycemia is a problem.
For type 2 diabetes, the Recommendations stress prompt intervention with metformin, dietary modification, exercise, and the addition of other drugs as needed to achieve and maintain glycemic levels as close to normal as possible. Insulin should be considered early on—even at the time of diagnosis in the presence of marked weight loss or other signs or symptoms of severe hyperglycemia.
Beyond metformin and insulin, the guidelines no longer recommend a sequence or schema for choosing among specific drugs for type 2 diabetes.
Glycemic control
The 2008 guidelines recognize the utility of continuous monitoring of interstitial glucose to supplement self-monitoring of blood glucose in type 1 diabetes, particularly for patients with hypoglycemia unawareness.
Glycemic goals remain largely unchanged, although the language has been revised. Hemoglobin A1c should in general be kept below 7%; the goal might be more rigorous—as close to normal as possible (<6%)—for selected patients and less stringent for others (e.g., with history of severe hypoglycemia or long-standing diabetes with minimal complications).
[Dr. Kirkman points out that the 2008 Recommendations were issued before release of data from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial that associated intensive glycemic control with increased mortality. She notes that the question remains unsettled and that data from this and other trials should clarify the situation soon. “Until we know more, we aren't changing anything,” she states.]
The section on hypoglycemia has been expanded to include discussions on prevention and hypoglycemia unawareness. Patients who have had episodes of severe hypoglycemia or who have hypoglycemia unawareness should be counseled to raise glycemic goals sufficiently to avoid further episodes for a period of at least several weeks. The same dysfunctions in counter-regulatory hormone release and autonomic response may both increase risk of and result from hypoglycemia. Such irregularities have been shown to normalize after a period in which hypoglycemia is rigorously avoided.
Preventing complications
There are fewer recommendations for BP control and lipid management than before, reflecting an attempt to emphasize those treatments found to be most effective, Dr. Kirkman says.
In the case of hypertension, the Recommendations now specify that drug treatment begin with an ACE inhibitor or angiotensin receptor blocker (ARB), with a diuretic added if necessary to achieve target pressures.
For dyslipidemia, the addition of statin therapy to lifestyle modification is recommended for patients with cardiovascular disease (CVD) or for those older than 40 or who have one or more CVD risk factors. Statins should be considered for others whose LDL remains >100 mg/dL.
Target LDL levels are set at <100 for those without overt CVD, with a lower goal (<70) an option for those with CVD, using high-dose statins if necessary. An alternative goal, added this year, is LDL reduction of 40% from baseline. The recommendations for nephropathy have also been shortened, to focus on the use of ACE inhibitors and ARBs for micro- and macroalbuminuria.
Older adults
The 2008 Recommendations put new emphasis on older adults and are the first to include specific guidelines for them. “They stress the need to individualize treatment,” says Dr. Kirkman.
Distinctions are based on functionality and life expectancy. For those patients who are functionally and cognitively intact and who have “significant” life expectancy, the Recommendations set the same goals as for younger adults. The glycemic goals can be relaxed for other patients as long as symptomatic or acute hyperglycemia is avoided. In screening for complications, those likely to lead to functional impairment, such as visual and lower-extremity involvement, deserve particular attention, the authors say.
The ADA's Clinical Practice Recommendations 2008 were published in Diabetes Care (2008;31 [suppl 1]) and are available online at http://care.diabetesjournals.org/content/vol31/Supplement_1/, accessed July 2, 2008.
Mr. Sherman is a medical writer in New York City.