Diabetes Mellitus Type I Overview
Overview Type 1 diabetes is B-cell destruction leading to absolute insulin deficiency. It accounts for 5-10% of all diabetes. Type I diabetes is divided into two types: Immune mediated and idiopathic. The traditional paradigm is of childhood onset with acute symptoms of DKA.
Diabetes: A group of metabolic diseases in which there are high blood sugar levels over a prolonged period.
Diabetes Mellitus Type I: Autoimmune destruction of beta cells in the pancreas
Diabetes Mellitus Type II: Insulin resistance followed by beta cell atrophy
Gestational Diabetes: diabetes diagnosed during the second half of pregnancy with no prior existing diabetes.
Diabetes Mellitus Type I Diagnosis
The age of onset and rate of B-cell destruction is quite variable:
- Rapid in infants and children
- Slow in others (mainly adults) such as occurs in Latent Autoimmune Diabetes of Adulthood (LADA).
This influences clinical presentation and may confuse diagnosis.
Acute onset of hyperglycaemic symptoms with ketoacidosis:
- Random plasma glucose > 11.1 mmol/L consistent with diagnosis
- HbA1c is not used in diagnosis
Autoimmune markers are not routinely used but can include:
- Glutamic acid decarboxylase (GAD65)
- Insulin (IAA)
- Tyrosine phosphatases (IA-2 & IA-2B)
Low or undetectable plasma C-peptide level supports the diagnosis.
Latent autoimmune diabetes of adulthood
- A subtype of autoimmune Type 1 diabetes sometimes misdiagnosed as T2D.
- Slowly progressive destruction of Beta cells.
- May appear to respond to oral agents initially.
- Less likely to have other features of metabolic syndrome (central obesity, HT, dyslipidaemia).
- More likely to have history of other autoimmune diseases.
- Starting insulin early may help to preserve beta cell insulin production
Criteria to standardize the definition:
- Age of onset usually > 30y
- Positive titre for at least one T1D autoantibody
- Not treated with insulin within the first 6 months after diagnosis
Diabetes Mellitus Type I Management
- HbA1c target <7
- BSL 4-6 pre meal and 4-8 post meal
- Patient education and pscyhosocial support
- Hypoglcyaemic symptoms and management
- Glucose monitoring
- Self glucose monitoring
- Continous glucose monitoring (which measure inersitial glucose)
- Multidisplnary team
- Insulin (causes weight gain)
- Continous subcutaenous insulin pump therapy
- Non-insulin treatment (all cause weight loss)
- GLP-1 receptor agonist
- SGLT2 inhibitors
- Pancreas transplantation (curative)
- Islet transplantation
Complications and Prognosis
- Increased risk of other autoimmune disease
- Autoimmune thyroid disease
- Addison's disease
- Coeliac disease
- Diabetic ketoacidosis