Diabetes, Type II

Table 1.

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications – OTC drugs or Herbals – that might affect the lab results?

Given inherent variability in all laboratory testing, both preanalytical and analytical, it is possible that patients with a lab result over the threshold for diabetes have a repeated value near the margins but below the diagnostic criteria for diabetes. It is recommended that such patients be monitored closely and their testing be repeated in approximately 3-6 months.

A drop in glucose levels may occur if the specimen is not tested immediately, leading to inaccurate reporting of blood glucose levels. It is recommended that blood be drawn in a gray-top tube containing sodium fluoride, which will inhibit glycolysis within 1 hour. Blood samples drawn in a red-top tube for serum glucose or in a green-top tube for plasma glucose will demonstrate a 2-3% decrease in glucose concentration per hour. In addition, patients suffering from sepsis or conditions that result in high white blood cell counts, such as chronic lymphocytic leukemia, may have artificially low glucose concentrations because of an increased rate of glucose metabolism as a consequence of leukocytosis and activated neutrophils.

Mean FPGs tend to be higher earlier in the day, thus, it is recommended that blood for this test be drawn in the morning. In addition, plasma glucose levels, typically, vary from day to day and can be affected by other factors, such as acute stress.

Although the A1C test can overcome many of the mentioned issues, caution in interpreting results must be used, as hemoglobinopathies, age, and other medical illnesses that affect red blood cell survival make interpreting the results difficult. Thus, use of this test may result in an over-diagnosis of the elderly, African-Americans, patients with an iron deficiency, or patients genetically predisposed to increased levels of hemoglobin concentration. A correlation between decreased A1C levels and pregnancy has also been well documented. Likewise, use of the A1C test alone may not be adequate for the diagnosis of diabetes in patients with anemia, hemoglobinopathies, or kidney disease.

What Lab Results Are Absolutely Confirmatory?

Laboratory tests used for diagnosis are also used for confirmation. Typically, if a lab test results in a diagnosis of diabetes, the same test is repeated on a subsequent day for confirmation. If results are simultaneously available for two separate tests and both indicate diabetes, additional testing is not required for confirmation. If, however, the results are discordant, the test with result above the diagnostic threshold for diabetes should be repeated. Diagnosis is then based on the results of the repeated test.

Additional Issues of Clinical Importance

Following a diagnosis of diabetes, patients should seek care from a medical team comprised of physicians, nurse practitioners, physician’s assistants, nurses, dietitians, pharmacists, and mental health professionals to implement a management plan for their disease.

In nonpregnant adults, the American Diabetes Association (ADA) recommends an A1C goal greater than 7.0%, a preprandial capillary plasma glucose of 70-130 mg/dL (3.9-7.2 mmol/L), and a peak postprandial capillary plasma glucose (2 hours after eating) of less than 180 mg/dL (10 mmol/L). For women with type I or type II diabetes who become pregnant, the optimal glycemic goals set by the ADA include a premeal, bedtime, and overnight glucose of 60-99 mg/dL (3.3-5.4 mmol/L), a peak postprandial glucose of 100-129 mg/dL (5.4-7.1 mmol/L), and an A1C of 6.5%.

When establishing a treatment plan for achieving glycemic goals, it is important to consider patient age, duration of diabetes, and presence of cardiovascular disease to reduce the risk of hypoglycemic events.

Additional ADA recommendations for blood pressure, lipids, and triglycerides for patients with diabetes are listed in Table 3.