From the Guidelines
The workup for Type 1 diabetes mellitus (T1DM) should include plasma blood glucose rather than A1C to diagnose the acute onset of type 1 diabetes in individuals with symptoms of hyperglycemia, as well as autoantibody testing and assessment of endogenous insulin production. The initial testing should include fasting plasma glucose, random plasma glucose with symptoms, or hemoglobin A1c, and confirmation of T1DM specifically requires autoantibody testing, including glutamic acid decarboxylase (GAD), islet cell (ICA), insulin (IAA), and zinc transporter 8 (ZnT8) antibodies 1.
Key Components of T1DM Workup
- Autoantibody testing to confirm T1DM diagnosis
- Assessment of endogenous insulin production through C-peptide levels
- Comprehensive metabolic panel
- Lipid profile
- Thyroid function tests (TSH, free T4)
- Celiac disease screening (tissue transglutaminase antibodies)
- Urinalysis with microalbumin-to-creatinine ratio to assess for early nephropathy
- Baseline ophthalmologic examination for retinopathy
- Screening for diabetic ketoacidosis in newly diagnosed patients presenting with hyperglycemia According to the most recent guidelines, the presence of two or more autoantibodies predicts clinical diabetes and may serve as an indication for intervention 1. The staging of type 1 diabetes includes three distinct stages, with stage 1 characterized by the presence of two or more autoantibodies and normoglycemia, stage 2 characterized by autoantibodies and dysglycemia, and stage 3 characterized by overt hyperglycemia and symptoms 1.
Importance of Early Detection and Intervention
- Early detection and intervention can help prevent or delay the onset of clinical diabetes
- Autoantibody testing can identify individuals at high risk of developing T1DM
- Assessment of endogenous insulin production can help determine the severity of the disease
- Comprehensive evaluation and monitoring can help establish baseline values and track disease progression and complications 1.
From the Research
Type 1 Diabetes Mellitus Workup
- Type 1 diabetes mellitus (T1DM) is a chronic disease characterized by insulin deficiency due to pancreatic β-cell loss and leads to hyperglycaemia 2
- The pathogenesis of T1DM is thought to involve T cell-mediated destruction of β-cells, and islet-targeting autoantibodies can be used to identify and study individuals who are at risk of developing T1DM 2
- A cure is not available, and patients depend on lifelong insulin injections, with novel approaches to insulin treatment being developed 2
Diagnostic Criteria
- Hemoglobin A1c (HbA1c) is the most important criterion controlling long-term complications of diabetes, and its level is affected by fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) 3, 4, 5
- The current diagnostic criterion of HbA1c ≥ 6.5% has a low sensitivity compared to FPG ≥ 126 mg/dL and 2-hour plasma glucose (2hPG) ≥ 200 mg/dL 4
- FPG and PPG significantly impact HbA1c and time-in-range (TIR), and balanced management of both is important to achieve glycemic goals for people with diabetes on multiple daily injection insulin therapy 5
Predictive Indicators for Diabetes Mellitus
- Combining HbA1c with FPG can help identify subgroups of people with impaired fasting glucose (IFG) at highest risk of diabetes mellitus (DM) 6
- Patients with both IFG and abnormal HbA1c have a higher risk of DM than patients with IFG alone, and should have the highest priority in diabetes prevention programs 6
- Other risk factors for DM in patients with IFG include body mass index ≥27.5 kg/m2, serum triglyceride level ≥150 mg/dL, family history of DM, and low level of high-density lipoprotein-cholesterol 6