Standards of Medical Care for Diabetes

Standards of Medical Care for Patients With Diabetes Mellitus

1. American Diabetes Association

Diabetes is a chronic illness that requires continuing medical care and patient self-management education to prevent acute complications and to reduce the risk of long-term complications. Diabetes care is complex and requires that many issues, beyond glycemic control, be addressed. A large body of evidence exists that supports a range of interventions to improve diabetes outcomes.

These standards of care are intended to provide clinicians, patients, researchers, payers, and other interested persons with the components of diabetes care, treatment goals, and tools to evaluate the quality of care. While individual preferences, comorbidities, and other patient factors may require modification of goals, targets that are desirable for most patients with diabetes are provided. These standards are not intended to preclude more extensive evaluation and management of the patient by other specialists as needed. For more detailed information, refer to Skyler (Ed.): Medical Management of Type 1 Diabetes (1) and Zimmerman (Ed.): Medical Management of Type 2 Diabetes (2).

The recommendations included are diagnostic and therapeutic actions that are known or believed to favorably affect health outcomes of patients with diabetes. A grading system (Table 1), developed by the Association and modeled after existing methods, was utilized to clarify and codify the evidence that forms the basis for the recommendations

CLASSIFICATION, DIAGNOSIS, AND SCREENING

Classification

In 1997, the American Diabetes Association issued new diagnostic and classification criteria (3).

The classification of diabetes mellitus includes four clinical classes

1. Type 1 diabetes (β-cell destruction, usually leading to absolute insulin deficiency)
2. Type 2 diabetes (Results from a progressive insulin secretory defect on the background of insulin resistance)
3. Other specific types of diabetes (due to other causes, e.g., genetic defects in β-cell function, genetic defects in insulin action, diseases of the exocrine pancreas, drug or chemical induced)
4. Gestational diabetes mellitus (GDM) (diagnosed during pregnancy)

Diagnosis

Criteria for the diagnosis of diabetes in nonpregnant adults are shown in Table 2. Three ways to diagnosis diabetes are available and each must be confirmed on a subsequent day. Because of ease of use, acceptability to patients and lower cost, the fasting plasma glucose (FPG) is the preferred test.

Hyperglycemia not sufficient to meet the diagnostic criteria for diabetes is categorized as either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), depending on whether it is identified through a FPG or an oral glucose tolerance test (OGTT):   IFG = FPG ≥110 mg/dl (6.1 mmol/l) and  <126 mg/dl (7.0 mmol/l)  Or FPG 110 mg/dl (6.1 mmol/l)  to 125 mg/dl (6.9 mmol/l) IGT = 2-h PG ≥140 mg/dl (7.8 mmol/l)  and <200 mg/dl (11.1 mmol/l)  Or 2-h PG 140 mg/dl (7.8 mmol/l) to  199 mg/dl (11.0 mmol/l)  

Both categories, IFG and IGT, are risk factors for future diabetes and cardiovascular disease. Recent studies have shown that lifestyle interventions can reduce the rate of progression to type 2 diabetes (5,6,7).

Screening

Generally, people with type 1 diabetes present with acute symptoms of diabetes and markedly elevated blood glucose levels. Type 2 diabetes is frequently not diagnosed until complications appear, and approximately one-third of all people with diabetes may be undiagnosed. Although the burden of diabetes is well known, the natural history is well characterized, and there is good evidence for benefit from treating cases diagnosed through usual clinical care, there are no randomized trials demonstrating the benefits of early diagnosis through screening of asymptomatic individuals (8). Nevertheless, there is sufficient indirect evidence to justify opportunistic screening in a clinical setting of individuals at high risk. Criteria for testing for diabetes in asymptomatic, undiagnosed adults are listed in Table 3. The recommended screening test for nonpregnant adults is the FPG.

The incidence of type 2 diabetes in children and adolescents has been shown to be increasing. Consistent with screening recommendations for adults, only children and youth at increased risk for the presence or the development of type 2 diabetes should be tested (9). See Table 4.

Detection and diagnosis of GDM

Risk assessment for GDM should be undertaken at the first prenatal visit. Women with clinical characteristics consistent with a high risk for GDM (those with marked obesity, personal history of GDM, glycosuria, or a strong family history of diabetes) should undergo glucose testing as soon as possible (10). A fasting plasma glucose ≥126 mg/dl or a casual plasma glucose ≥200 mg/dl meets the threshold for the diagnosis of diabetes, if confirmed on a subsequent day. High-risk women not found to have GDM at the initial screening and average-risk women should be tested between 24 and 28 weeks of gestation. Testing should follow one of two approaches:

1. One-step approach: perform a diagnostic OGTT.
2. Two-step approach: perform an initial screening by measuring the plasma or serum glucose concentration 1 h after a 50-g oral glucose load (glucose challenge test [GCT]) and perform a diagnostic OGTT on that subset of women exceeding the glucose threshold value on the GCT. When the two-step approach is employed, a glucose threshold value ≥140 mg/dl identifies ∼80% of women with GDM, and the yield is further increased to 90% by using a cutoff of ≥130 mg/dl.

Diagnostic criteria for the 100-g OGTT is as follows: ≥95 mg/dl fasting; ≥180 mg/dl at 1 h; ≥155 mg/dl at 2 h; ≥140 mg/dl at 3 h. Two or more of the plasma glucose values must be met or exceeded for a positive diagnosis. The test should be done in the morning after an overnight fast of 8–14 h. The diagnosis can be made using a 75-g glucose load, but that test is not as well validated for detection of at-risk infants or mothers as the 100-g OGTT.

Low risk status requires no glucose testing, but this category is limited to those women meeting all of the following characteristics:

1. Age <25 years
2. Weight normal before pregnancy
3. Member of an ethnic group with a low prevalence of GDM
4. No known diabetes in first-degree relatives
5. No history of abnormal glucose tolerance
6. No history of poor obstetric outcome

Recommendations

 

A-Level evidence

1. In those with IFG/IGT, lifestyle modification should be considered.

Expert consensus

1. The FPG is the preferred test to screen for and diagnose diabetes.
2. Screen for diabetes in high-risk, asymptomatic, undiagnosed adults and children within the health care setting.
3. Screen for diabetes in pregnancy using risk factor analysis and screening tests as noted.