How is diabetes mellitus diagnosed?
The Metabolic Syndrome
The metabolic syndrome is a cluster of findings that taken together make it a risk factor for developing Type 2 diabetes. The abdominal obesity of the metabolic syndrome is associated with insulin resistance that results in subsequent hyperglycemia and vascular disease. The elevated triglycerides, low HDL-cholesterol, hypertension, and elevated fasting plasma glucose that are seen with this syndrome interrelate in negative ways.
The diagnosis of DM is via documentation of hyperglycemia. Any one of the three American Diabetes Association criteria below establishes the diagnoses of diabetes:
- Fasting plasma glucose (FPG) values ≥126 mg/dL. (Normal is < 100.)
- Two-hour plasma glucose values of ≥200 mg/dL after a 75 g oral glucose challenge in the oral glucose tolerance test (OGTT). (Normal is < 140.)
- A1c values ≥6.5%. (Normal is 6%.) The glycated hemoglobin A1c is a reflects a composite of glycemic control over the previous month(s).
Any abnormal result of these criteria require re-testing.
Other Causes of Hyperglycemia
There are other causes of hyperglycemia that must be ruled out. They include “stress hyperglycemia,” which is not DM but is a risk for developing it. Steroids and other medications during severe illness can cause stress hyperglycemia.
Diabetes occurs with and augments other co-morbidities. The work-up for diabetes includes seeking and identifying co-morbidities to implement a global treatment plan. These include the following:
- Smoking cessation
- Hypertension, hyperlipidemia, and other cardiovascular risks
- Visual changes due to diabetic retinopathy and hearing impairment
- Kidney function tests, liver abnormalities, and periodontal disease
- Cognitive impairment
- Bone weakness/fractures