endocrine and metabolic disorders
Diabetes Mellitus (DM)
Diagnosis of Diabetes Mellitus
Fasting plasma glucose (FPG) levels Glycosylated hemoglobin (HbA1C) Sometimes oral glucose tolerance testing Diabetes mellitus is suggested by typical symptoms and signs and confirmed by measurement of plasma glucose ( Diagnosis references , ). OGTT is more sensitive for diagnosing diabetes and impaired glucose tolerance but is less convenient and reproducible than FPG. It is therefore rarely used routinely, except for diagnosing Diabetes Mellitus in Pregnancy and for research purposes. In practice, diabetes mellitus or impaired fasting glucose regulation is often diagnosed using random measures of plasma glucose or of HbA1C. A random glucose value>200 mg/dL (>11.1 mmol/L) may be diagnostic, but values can be affected by recent meals and must be confirmed by repeat testing; testing twice may not be necessary in the presence of symptoms of diabetes. HbA1C is a form of hemoglobin that is chemically attached to a sugar that increases with blood glucose and has a validated relationship with average glucose level over the preceding 3 months. HbA1C measurements are now included in the diagnostic criteria for diabetes: HbA1C≥6.5%=diabetes HbA1C 5.7 to 6.4%=prediabetes or at risk of diabetes However, HbA1C is an indirect measure of blood glucose; values may be falsely high or low (see Monitoring Diabetes Treatment ) and can vary with race/ethnicity. Tests must be done in a certified clinical laboratory with an assay that is certified and standardized to a reference assay. Point-of-care finger-stick HbA1C measurements should not be used for diagnostic purposes, although they can be used for monitoring diabetes control. Urine glucose measurement, once commonly used, is no longer used for diagnosis or monitoring because it is neither sensitive nor specific. Point-of-care fingerstick HbA1C tests are not accurate enough to be used for initial diagnosis of diabetes. All patients with type 1 diabetes mellitus should begin screening for diabetic complications 5 years after diagnosis. For patients with type 2 diabetes, screening begins at diagnosis. Typical monitoring for complications includes Foot examination Funduscopic examination Urine testing for albuminuria Measurement of serum creatinine and lipid profile Foot examinationshould be done at least annually for impaired sense of pressure, vibration, pain, or temperature, which is characteristic of peripheral neuropathy. Pressure sense is best tested with a monofilament esthesiometer (see figure). The entire foot, and especially skin beneath the metatarsal heads, should be examined for skin cracking and signs of ischemia or infection, such as ulcerations, gangrene, fungal nail infections, deceased pulses, and hair loss. Funduscopic examinationshould be done by an ophthalmologist; the screening interval is typically annually for patients with any retinopathy to every 2 years for those without retinopathy on a prior examination. If retinopathy shows progression, more frequent evaluation may be needed. Spot or 24-hour urine testingis indicated annually to detect albuminuria, and serum creatinine should be measured annually to assess kidney function. Testing for cardiovascular diseaseis needed. Many physicians consider baseline ECG important given the risk of heart disease. Lipid profile should be checked at least annually and more often when abnormalities are present. Blood pressure should be measured at every examination. 1.American Diabetes Association: Standards of Medical Care in Diabetes.Diabetes Care46 (Supplement 1): 1-291, 2023. 2.Holt RIG, DeVries JH, Hess-Fischl A, et al: The management of type 1 diabetes in adults. A consensus report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD).Diabetologia64(12):2609–2652, 2021. doi: 10.1007/s00125-021-05568-3 