From the Guidelines
The approach to a patient with features suggestive of Type 1 Diabetes Mellitus (T1DM) should involve immediate medical treatment and education for self-management, with consideration of the AABBCC approach to distinguish diabetes type: Age, Autoimmunity, Body habitus, Background, Control, and Comorbidities 1.
Key Considerations
- Diagnosis: No single clinical feature confirms T1DM in isolation, and misdiagnosis can occur in up to 40% of adults with new T1DM 1.
- Islet Autoantibodies: Measurement of islet autoantibodies, such as glutamic acid decarboxylase (GAD), islet tyrosine phosphatase 2 (IA-2), and/or zinc transporter 8 (ZnT8), can be useful in distinguishing T1DM from other types of diabetes 1.
- C-peptide Test: A C-peptide test can help determine the degree of beta-cell function and distinguish T1DM from other types of diabetes, particularly in individuals receiving insulin treatment 1.
- Genetic Testing: Genetic testing for monogenic diabetes may be considered in individuals with suggestive features, such as a family history of diabetes or specific monogenic causes 1.
- Treatment: Insulin therapy is typically required for individuals with T1DM, and education on self-management is essential for optimal care 1.
Diagnostic Algorithm
The diagnostic algorithm for suspected T1DM in newly diagnosed adults involves testing islet autoantibodies, considering age, body habitus, and background, and measuring C-peptide levels if necessary 1.
Clinical Decision-Making
Clinical decision-making should be based on a combination of clinical features, laboratory results, and individual patient characteristics, with consideration of the potential for misdiagnosis and the importance of timely initiation of insulin therapy in individuals with T1DM 1.
From the Research
Approach to a Patient with Features Suggestive of Type 1 Diabetes Mellitus (T1DM)
The approach to a patient with features suggestive of T1DM involves several steps, including:
- Quantifying venous plasma glucose, which is the gold standard in diagnostics 2
- Determining the HbA1c and OGTT as a precaution 2
- Screening for autoimmune disorders, such as PGAS, once manifestation of diabetes is detected 2
- Identifying and studying individuals who are at risk of developing T1DM using islet-targeting autoantibodies 3
- Classifying patients into distinct diabetic subtypes based on factors such as age of onset, immune system regulation, and autoantibodies 4
Diagnostic Approach
The diagnostic approach to T1DM involves:
- Determining antibodies, such as IA-2- and GAD-antibodies, and optionally C-peptide, in patients with a vague constellation of clinical picture 2
- Finding uric ketones, BGA, and other biomarkers to ensure diagnosis 2
- Recognizing the three stages of T1DM, including stage 1 (normoglycaemic and positive for autoantibodies to β-cell antigens), stage 2 (asymptomatic with dysglycaemia), and stage 3 (defined by glucose levels consistent with the definition of diabetes mellitus) 5
Management and Treatment
The management and treatment of T1DM involve:
- Lifelong insulin injections, with novel approaches to insulin treatment, such as insulin pumps, continuous glucose monitoring, and hybrid closed-loop systems, in development 3
- Extending the insulin-free period and/or avoiding unnecessary insulin therapy, which are important goals in the management of stage 3a T1DM 5
- Disease-modifying therapies, such as immuno- and regenerative therapies, which aim to target autoimmune mechanisms and prevent β-cell destruction 6