Meeting the American Diabetes Association Standards of Care: An Algorithmic Approach to Clinical Care of the Diabetes Patient

By Mayer B. Davidson

Improving glycemic, lipid, and blood pressure outcomes is the essence of diabetes care. Maintaining consistently positive results is an ongoing challenge for every healthcare professional. After years of clinical practice, Mayer Davidson, MD, has developed a series of algorithmic techniques that can increase positive results. Based on ADA's Standards of Care, this book offers detailed treatment algorithms that have been shown to be clinically effective in improving outcomes in people with diabetes.

• Language: English
• Publisher: American Diabetes Association
• Release date: Feb 5, 2010
• ISBN: 9781580403665

Mayer B. Davidson

Mayer B. Davidson, MD, is a well-known and respected researcher and an expert in clinical endocrinology. He is a Professor of Medicine at the UCLA School of Medicine and a Principal Investigator at the Clinical Center for Research Excellence at the Charles Drew University of Medicine and Science (Los Angeles). He is very active in the ADA community and was Editor-in-Chief of Diabetes Care from 2002 to 2006 and President of the American Diabetes Association from 1997 to 1998.

Book preview

Chapter 1

Laying the Groundwork

BACKGROUND FOR EVIDENCE-BASED ADA GUIDELINES FOR STANDARDS OF DIABETES CARE

Diabetes mellitus has a profound effect on the health of our population. Diabetic retinopathy is the leading cause of blindness in people between 20 and 74 years of age (1). Diabetic nephropathy is the leading cause of patients undergoing dialysis for end-stage renal disease (2). Diabetic peripheral neuropathy is the underlying cause of non-traumatic lower-extremity amputations in diabetic patients (3). More than half of lower-extremity amputations occur in people with diabetes (4), who at the time these data were collected constituted only 4.5% of the population (5). The prevalence of coronary artery disease is twofold higher in men with diabetes and fourfold higher in women with diabetes, compared with appropriate nondiabetic control subjects (6). Strokes are two to three times more common in people with diabetes than in people without the disease (7). Peripheral arterial disease is also much more common in diabetic patients than in nondiabetic individuals (8).

Much of this devastation can be avoided. The microvascular complications of diabetes could be markedly reduced, if not eliminated, if near-euglycemia is maintained. Progression of early kidney disease to late-stage nephropathy can be forestalled by appropriate (non-glycemic) therapy. Although macrovascular disease cannot be entirely prevented, its effects can be sharply curtailed with appropriate treatment for lipids and blood pressure, smoking cessation, and ingestion of aspirin. Evidence for these important assertions will be briefly summarized.

GLYCEMIA

There have been five studies in over 2,000 type 1 (9–11) and type 2 (12,13) diabetic patients demonstrating that there is virtually no development or progression of retinopathy and nephropathy over 4–9 years if mean A1C levels are maintained at <7.0%. Figure 1 shows this relationship in type 1 diabetic patients enrolled in the well-known Diabetes Control and Complications Trial (DCCT). In two of these studies (9,12), an intervention that lowered glycemia resulted in much less microvascular complications, proving a causative relationship between near-euglycemia and these improved outcomes.

Figure 1. DCCT: Relative risk of progression of diabetic complications by mean HbA1c.*

There is much less evidence that lowering glycemia will have a beneficial effect on macrovascular disease, at least in the near- to mid-term. Although there is an association between glycemia and cardiovascular disease (CVD), it extends all the way down into the mid-normal range (14). For instance, in men between the ages of 40 and 74 years, there was a 2.7-fold increase of a myocardial infarction in individuals with A1C levels between 5.0 and 5.4% compared with individuals with A1C levels <5.0% over 4 years (15). In another study involving nondiabetic adults, there was a 2.4-fold increase in the relative risk for a CVD event over 8–10 years for each 1% increase in A1C levels >4.6% (16).

In older individual studies (17) or in a meta-analysis (18), no beneficial effect was seen on CVD by lowering glycemia in type 2 diabetic patients. Three larger recent studies that focused specifically on the effect of glucose control on CVD also failed to demonstrate a beneficial effect. In the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study (19), 10,251 patients (median baseline A1C level of 8.1%), 35% of whom had a previous CVD event, were randomized to receive intensive (goal A1C level of <6.0%) or usual care (goal A1C level of 7.0–7.9%). The study was stopped after 3.5 years because there was a significantly higher CVD mortality in the intensively treated group (achieved median A1C level of 6.4%) compared with the control group (achieved median A1C level of 7.5%) despite the fact that the intensively treated group had a significant reduction in nonfatal myocardial infarctions.

In the ADVANCE study (20), 11,140 patients (mean A1C level of 7.5%) with a history of major macrovascular or microvascular disease or at least one other risk factor for vascular disease (besides diabetes) were randomized to receive intensive glucose control (goal A1C ≤6.5%) or standard glucose control (targeted A1C defined on the basis of local guidelines). At the end of the study (median duration of 5 years), there was no difference in major macrovascular events (CVD death, nonfatal myocardial infarction, nonfatal stroke) between the intensively treated patients (achieved mean A1C of 6.5%) and the patients treated under standard conditions (achieved mean A1C of 7.3%). There was a significant reduction in the development of nephropathy in the intensively treated group, as has been found in many other studies evaluating microvascular complications.

In the Veterans Affairs Diabetes Trial (VADT) (21), 1,791 veterans (mean baseline A1C level of 9.4%) were randomized to receive intensive or standard treatment. A total of 40% of the cohort had had a prior CVD event. At the end of the study (median duration of 5.6 years), there was no difference in major CVD events (death, myocardial infarction, stroke, heart failure, amputation due to ischemia, intervention for coronary, or peripheral arterial disease) in the intensively treated (achieved A1C level of 6.9%) and standard (achieved A1C level of 8.4%) groups. As in the ADVANCE study, there was a significant decrease in the progression of albumin excretion in the intensively treated group.

Although there were no significant reductions in CVD events after a mean of 6.5 years of intensive treatment in type 1 diabetic patients, there was a significant decrease after a further 10.5 years (22). Similarly, in type 2 diabetic patients, there were no statistical differences in myocardial infarctions and death from any cause between intensive and conventional treatment after a median of 10.5 years, but significant reductions in both were seen in the intensively treated group after a further 10 years (23). These beneficial effects on macrovascular disease occurred despite the fact that between-group differences in A1C levels in both studies were lost within 1 year after the DCCT and U.K. Prospective Diabetes Study (UKPDS) were concluded, supporting the importance of near-euglycemia early in the course of diabetes.

Based on these data, the American Diabetes Association (ADA) recommends an A1C treatment goal of <7.0% (24), with which the author agrees.

LIPIDS

There is no doubt, of course, that lowering LDL cholesterol levels has a causative effect on reducing cardiac events in the general population (25). Lipid-lowering drugs are equally effective in reducing the relative risk of coronary disease in people with and without diabetes, i.e., the percent reduction is the same (26). However, the reduction of absolute risk is threefold greater in diabetic patients (26) because approximately three times as many people with diabetes are at risk for a CVD event than individuals without diabetes. Relative risk reduction is similar across all baseline LDL cholesterol levels (27) and is equally beneficial in older and younger diabetic patients (27,28) and in men and women (27). There is an ∼20% relative risk reduction for a 40 mg/dl fall in LDL cholesterol levels (25,29). Not surprisingly then, cardiac events were 25% lower in diabetic patients receiving 80 mg atorvastatin compared with 10 mg (30). Treatment of ∼30 type 2 diabetic patients with a statin will prevent one major cardiac event over 4 years (31,32). The use of statins has been shown to be cost-effective (33,34).

Based on these data, the ADA (24) recommends that all type 2 diabetic patients over the age of 40 years should receive a statin regardless of baseline LDL cholesterol levels. Statins should also be considered for younger patients at high risk for CVD. The goal for patients without clinical evidence of CVD is <100 mg/dl. For these with clinical evidence of CVD, the goal is <70 mg/dl.

What about triglyceride concentrations? Very high triglyceride levels (>1,000 mg/dl) can cause pancreatitis. Therefore, patients presenting with values >1,000 mg/dl should be treated initially with a fibrate. Because all diabetic patients >40 years of age will also be taking a statin, the fibrate should be fenofibrate, not gemfibrozil. The combination of a fibrate and a statin increases the risk of side effects. Fenofibrate is less likely to do so because it does not affect the pharmacokinetics of statins as gemfibrozil does.

Very few patients have high enough triglyceride levels to require initial fibrate treatment. Many patients, however, will have elevated triglyceride levels, and most of them have depressed HDL cholesterol levels. It is not clear whether the risk is mainly due to high triglyceride levels or low HDL cholesterol levels. Fenofibrate treatment of type 2 diabetic patients who were not taking a statin had much less of an effect on CVD (35) than published reports with statins. The National Cholesterol Education Program (36) and the ADA (24) suggest the following approach to triglyceride concentrations. Once the LDL cholesterol goal is reached, non-HDL cholesterol (total cholesterol minus HDL cholesterol) should be calculated in patients whose triglyceride levels are >200 mg/dl. Triglycerides are carried on many different lipoproteins, and non-HDL cholesterol levels reflect the more atherogenic ones. The goal for non-HDL cholesterol is <30 mg/dl above the LDL cholesterol goal.

RENAL EVALUATION

Many studies have evaluated the effects of either angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) on renal disease in diabetic patients. Studies on patients with clinical proteinuria (i.e., albumin-to-creatinine ratios >300 μg/mg, 24-h urinary albumin >300 mg, 24-h urinary protein >500 mg), many of whom had renal insufficiency, used a primary end point of a doubling of serum creatinine levels and secondary end points of dialysis, renal transplant, or death. In randomized control trials, both an ACE inhibitor (37) and an ARB (38,39) significantly reduced these end points compared with a placebo. Either blood pressure levels were kept the same in the two groups (37) or the benefits were independent of blood pressure changes (38,39). Many smaller studies support these conclusions