What are the different types of diabetes and their management approaches?

Different Types of Diabetes and Their Management Approaches

Diabetes is classified into four main categories: Type 1, Type 2, Gestational Diabetes Mellitus (GDM), and specific types due to other causes, each requiring distinct management approaches based on their underlying pathophysiology. 1

Type 1 Diabetes

• Pathophysiology: Caused by autoimmune β-cell destruction leading to absolute insulin deficiency 1
• Presentation:
  • Classic presentation in children with diabetic ketoacidosis (DKA) in approximately one-third of cases
  • Adult-onset may present more variably without classic symptoms 1
• Diagnosis:
  • Testing for islet autoantibodies (GAD, IA-2, ZnT8) helps confirm diagnosis
  • C-peptide testing useful after disease duration >3 years 1
• Management:
  • Insulin therapy is essential for survival
  • Regular blood glucose monitoring
  • Carbohydrate counting and insulin dose adjustment

Type 2 Diabetes

• Pathophysiology: Characterized by progressive loss of β-cell insulin secretion on a background of insulin resistance 1
• Presentation:
  • Often asymptomatic and discovered during routine screening
  • May occasionally present with DKA, particularly in ethnic minorities 1
• Management:
  • Lifestyle modifications (diet, exercise, weight management)
  • Oral antidiabetic medications
  • Injectable therapies including insulin when needed
  • Regular monitoring of complications

Gestational Diabetes Mellitus (GDM)

• Definition: Diabetes diagnosed in the second or third trimester of pregnancy that was not clearly overt diabetes prior to gestation 1
• Epidemiology: Affects approximately 8.3% of pregnancies 1
• Screening: Typically occurs at 24-28 weeks of gestation 1
• Management:
  • Dietary measures and blood glucose monitoring
  • Insulin therapy required in 20-30% of cases
  • Glycemic targets: fasting blood glucose <5.2 mmol/L and 2-hour postprandial <6.6 mmol/L 1

Specific Types Due to Other Causes

Monogenic Diabetes

• MODY (Maturity-Onset Diabetes of the Young):

  • Single gene mutations affecting beta-cell function 2
  • Different subtypes with varying clinical presentations
  • Treatment varies by subtype:
    • MODY2 (glucokinase mutations): Often managed with diet alone
    • MODY3 (HNF1A mutations): Often responsive to sulfonylureas 2

• Neonatal Diabetes:

  • Permanent Neonatal Diabetes Mellitus (PNDM)
  • Transient Neonatal Diabetes
  • Mutations in Kir6.2 and SUR1 genes often respond to sulfonylurea treatment 2

Other Specific Types

• Secondary Diabetes:
  • Pancreatic diseases (pancreatitis, cystic fibrosis, hemochromatosis)
  • Endocrinopathies (Cushing's syndrome, acromegaly)
  • Drug-induced (glucocorticoids, atypical antipsychotics)
  • Genetic syndromes (Down syndrome, Klinefelter syndrome) 3

Diagnostic Criteria

• American Diabetes Association diagnostic criteria 1:
  • A1C ≥6.5% (48 mmol/mol)
  • Fasting plasma glucose ≥126 mg/dL (7.0 mmol/L)
  • 2-hour plasma glucose ≥200 mg/dL (11.1 mmol/L) during OGTT
  • Random plasma glucose ≥200 mg/dL (11.1 mmol/L) with classic symptoms

Clinical Considerations and Pitfalls

• Misdiagnosis is common: Up to 40% of adults with new-onset type 1 diabetes are initially misdiagnosed 1

• Age is not a reliable indicator: Both type 1 and type 2 diabetes occur across all age groups 1

• Atypical presentations:

  • Latent Autoimmune Diabetes in Adults (LADA): Adult-onset autoimmune diabetes with slower progression than typical type 1 4
  • Ketosis-Prone Diabetes (KPD): Presents with ketoacidosis but may not require long-term insulin 4

• Important clinical practice points:

  • Regular reassessment of diabetes classification is crucial, especially when treatment response is suboptimal 1
  • Genetic testing should be considered when clinical features suggest monogenic forms
  • Treatment should be tailored to the specific pathophysiology of the diabetes type