From the Guidelines
The workup for type 1 diabetes should include initial testing with fasting plasma glucose, random plasma glucose, and hemoglobin A1C, as well as autoantibody testing, including glutamic acid decarboxylase (GAD), islet cell antibodies (ICA), insulin autoantibodies (IAA), and zinc transporter 8 (ZnT8) antibodies, to confirm autoimmune etiology, as recommended by the most recent guidelines 1. The diagnosis of type 1 diabetes involves a comprehensive approach to confirm diagnosis and assess the patient's overall health status.
- Initial testing should include:
- Fasting plasma glucose (≥126 mg/dL indicates diabetes)
- Random plasma glucose (≥200 mg/dL with symptoms)
- Hemoglobin A1C (≥6.5% suggests diabetes)
- Specific to type 1 diabetes, autoantibody testing is crucial, including:
- Glutamic acid decarboxylase (GAD)
- Islet cell antibodies (ICA)
- Insulin autoantibodies (IAA)
- Zinc transporter 8 (ZnT8) antibodies as their presence confirms autoimmune etiology, as supported by recent studies 1.
- C-peptide levels should be measured to assess endogenous insulin production, with low levels supporting type 1 diagnosis. Additional workup includes:
- Comprehensive metabolic panel to evaluate electrolytes and organ function
- Urinalysis to check for ketones and glucose
- Thyroid function tests since autoimmune thyroid disease commonly coexists
- Screening for celiac disease with tissue transglutaminase antibodies is recommended due to increased prevalence in type 1 diabetes, as noted in recent guidelines 1. If diabetic ketoacidosis is suspected, arterial blood gases and serum ketones should be measured. This comprehensive evaluation helps distinguish type 1 from type 2 diabetes, guides immediate treatment decisions regarding insulin therapy, and identifies any comorbidities requiring concurrent management, ultimately improving morbidity, mortality, and quality of life outcomes 1.
From the Research
Workup for Type 1 Diabetes
- The primary treatment for type 1 diabetes mellitus (T1DM) is insulin therapy 2
- Typically, patients with T1DM require initiation with multiple daily injections at the time of diagnosis, which can include short-acting insulin or rapid-acting insulin analogue given before meals, along with intermediate or long-acting insulin 2
- The target glycated hemoglobin A1c (HbA1c) for children with T1DM is recommended to be < 7.5% (< 58 mmol/mol), while for nonpregnant adults, a glycemic target of HbA1c < 7% (53 mmol/mol) is considered appropriate 2, 3
Insulin Regimens
- Basal insulin analogues with a reduced peak profile and an extended duration of action are preferred for basal insulin therapy in T1DM 3
- Rapid-acting prandial analogues (such as aspart, glulisine, lispro) are preferred over regular human insulin for prandial glycemic control 3
- Faster-acting insulin aspart has been shown to have advantages in postprandial glucose coverage compared to conventional insulin aspart 4
Blood Glucose Monitoring
- Blood glucose monitoring is an integral part of effective insulin therapy and should not be omitted in the patient's care plan 2
- Fasting plasma glucose (FPG) values should be used to titrate basal insulin, while both FPG and postprandial glucose (PPG) values should be used to titrate mealtime insulin 2, 5
- Continuous glucose monitoring may improve glycemic control irrespective of treatment regimen 3
Glycemic Control
- Achieving a balanced management of both fasting plasma glucose (FPG) and postprandial glucose (PPG) is important to achieve glycemic goals for people with diabetes on multiple daily injection insulin therapy 6
- Reductions in FPG and PPG have been significantly associated with increased time in range (TIR) and improved HbA1c levels 6