● A random plasma glucose > 200 mg/dL (11.1 mmol/L) in a patient with classic symptoms of hyperglycemia or hyperglycemic crisis. Random (casual) plasma glucose test This test can be performed at any time of day when severe diabetic symptoms develop. Diabetes is diagnosed when the Fasting plasma glucose (FPG) FPG assesses fasting blood glucose levels. Fasting is defined as not have anything to eat or drink except water for at least eight hours before the test. The test is typically performed first thing in the morning before breakfast. (ADA, 2021n). Oral glucose tolerance test (OGTT) An OGTT is performed to assess insulin response to glucose loading. A fasting blood sugar is obtained before the ingestion of an oral glucose solution, and blood samples are drawn at specifically timed intervals. The oral glucose solution should contain the equivalent of 75 g anhydrous glucose dissolved in water (ADA, 2021a; Pagana et al., 2019). Results from the OGTT are (ADA, 2021a): ● Normal: less than 140 mg/dL. ● Prediabetes: 140 mg/dL to 199 mg/dL ● Diabetes: 200 mg/dL or higher Patient care considerations and patient teaching include the following important factors (Pagana et al., 2019; Rebar et al, 2019): ● The patient should follow their usual diet and exercise regimen for three days before the test. ● The patient must be instructed to fast for 12 hours before the OGTT. ● Certain drugs may be withheld before testing based on the recommendations of the patient’s health care provider. Examples of drugs that can interfere with test results are A1C test The A1C test is a blood test used to obtain information about a patient’s average blood glucose over the past three months. The A1C is used in the diagnosis of type 2 diabetes and prediabetes and is the primary test used for diabetes management (NIDDK, 2018e). The A1C test does not require fasting. Blood can be drawn at any time of day, thus making it more convenient than some other testing options. The test may also be used during the first health care pregnancy visit to determine if the woman had undiagnosed diabetes before becoming pregnant. After that, the oral glucose tolerance test (OGTT) or the glucose challenge test is used to test for gestational diabetes (NIDDK, 2018e; Pagana et al., 2019). The A1C test is based on attachment of glucose to hemoglobin in red blood cells. Although red blood cells are continually forming and dying, they typically live for approximately three months. The A1C can reflect blood glucose levels over the previous three months. Reported as a percentage, the higher the percentage, the higher the blood glucose levels have been (NIDDK, 2018e). Results of the A1C are (2021n): ● Normal: Less than 5.7% ● Prediabetes: 5.7 to 6.4% ● Diabetes: 6.5% or higher Recommendations from the ADA include (2021n): ● Assess glycemic status (A1C or other glycemic measurement) at least two times a year in patients who are meeting treatment goals (and who have stable glycemic control). ● Assess glycemic status at least quarterly, and as needed, in patients whose therapy has recently changed and/or who are not meeting glycemic goals. Healthcare Professional Consideration: Because A1C reflects average glucose status over several months, it has significant predictive value for diabetes complications. A1C testing should be performed routinely in all patients who have diabetes (ADA, 2021e).
Details about the various tests used in the diagnostic process follow.
blood glucose is >200 mg/dL (ADA,2021n).
FPG results are (ADA, 2021n): ● Normal: Less than 100 mg/dL ● Prediabetes: 100 mg/dL to 125 mg/dL ● Diabetes: 126 mg/dL or higher
hormonal contraceptives, salicylates, diuretics, phenytoin, and nicotinic acid. ● Fasting blood and urine specimens are obtained. ● An oral glucose solution is administered that consists of 75 g of glucose or dextrose for patients who are not pregnant or 100 g for pregnant patients. The patient must drink the entire glucose solution. The amount of glucose in solution is based on body weight for pediatric patients. ● During the OGTT, the patient must not use tobacco or ingest coffee or tea because these substances cause physiological stimulation. They must be told not to eat or drink anything during the testing period except for the oral glucose solution provided by the test administrator—except for water, which the patient is encouraged to drink. ● A venous blood sample is collected at 30- and 60-minutes post-ingestion of the glucose solution and at hourly intervals thereafter. ● Urine samples are collected at hourly intervals. ● During the period of testing, the patient should be monitored for dizziness, sweating, weakness, and giddiness, which are usually transient and self-limiting. Following are the A1C-range recommended goals (ADA, 2021e): ● An A1C goal for many nonpregnant adults of <7% (53 mmol/ mol) without significant hypoglycemia is appropriate. ● If using ambulatory glucose profile/glucose management indicator to assess glycemia, a parallel goal is a time in range of >70% with time below range <4%. ● Based on provider judgment and patient preference, achievement of lower A1C levels than the goal of 7% may be acceptable, and even beneficial, if it can be achieved safely without significant hypoglycemia or other adverse effects of treatment. ● Less stringent A1C goals (such as <8% [64 mmol/mol]) may be appropriate for patients with limited life expectancy, or where the harms of treatment are greater than the benefits. ● Reassess glycemic targets over time based on the criteria specific to various age groups. Table 1. Explanation of Results of Diabetes Screenings Test Normal Prediabetes Diabetes A1C Less than 5.7% 5.7% to 6.4% 6.5% or higher
Fasting plasma glucose
Less than 100 mg/dL
100 mg/dL to 125 mg/dL
126 mg/dL or higher
Oral glucose tolerance test
Less than 140 mg/dL
140 mg/dL to 199 mg/dL
200 mg/dL or higher
Compiled from: (ADA, 2021b; 2021e; 2021n)
Book Code: ANCCUS2423
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