Clinical Features of Type 1 & 2 Diabetes Flashcards
Epidemiology of Type 2 Diabetes
- Most common form of diabetes
- 85% of all diabetes in Caucasian populations
- 95% of all diabetes in other ethnic groups
What are the risk factors for Type 2 Diabetes?
-Genetics =Race -Increasing age -Central obesity -Low birth weight (hypertension and heart disease)
Describe the genetic component of Type 2 Diabetes
- Genome-wide association studies have identified >400 gene variants associated with an increased risk of Type 2 diabetes= polygenic
- Most relate to beta cell function or mass, rather than obesity/insulin resistance
- 40% of the overall risk of Type 2 diabetes is determined by genetic factors
- Relative with Type 2 Diabetes= x5 risk
Describe the prevalence of Type 2 Diabetes
- More than 25% of people of Asian origin aged>60 years suffer from diabetes (greater in all age groups than European)
- Massively different between ethnicities (genetically- code for central obesity, smaller pancreas, less beta cells)
Why does incidence and prevalence of Type 2 Diabetes increase with age?
- Beta cell function reduces with age
- Obesity increases with age (lower age on onset in more overweight people)
What are the stages of development of Type 2 Diabetes?
- Normal glucose tolerance
- Impaired glucose metabolism (insulin secretion 150%)
- Impaired glucose tolerance (50% tolerance)
- Type 2 Diabetes (secretion= 50%, tolerance= 70%)
What is the classical presentation of Type 2 Diabetes?
- Asymptomatic – found on routine screening
- Thirst (hypothalamus, leads to polydipsia), polyuria (osmotic symptoms= glucose in urine)
- Malaise, chronic fatigue
- Infections, e.g. thrush (candidiasis, skin infection, UTI); boils (sugary environment)
- Blurred vision (lens in eyes coated in glucose= osmotic drag for interstitial fluid= refractive error as lens distorted)
- Complication as presenting problem (e.g. retinopathy, neuropathy)
What are the features of metabolic syndrome?
-Central obesity
-High blood pressure
-High triglycerides
-Low HDL-cholesterol
=very atherogenic
-Insulin resistance
What other medical disorders are associated with Type 2 Diabetes?
- Obstructive Sleep Apnoea
- Polycystic Ovarian Disease
- Hypogonadotropic Hypogonadism in men (testosterone levels drop more quickly, adipose inhibits trophin, more aromatase)
- Non-Alcoholic Fatty Liver Disease= cirrhosis and hepatocellular carcinoma
What are the symptoms of Type 1 Diabetes at presentation?
- Polyuria, thirst
- Fatigue, malaise
- Weight loss
- Blurred vision
- Nausea, vomiting
- Usual presentation is in childhood, adolescence or young adulthood
- Can present at any age, more acute onset
- Short history (weeks) of florid osmotic symptoms and rapid weight loss; Ketonuria/ketonaemia is usually present
- High risk of metabolic decompensation - ketoacidosis (insulin deficiency= less glucose in cells= generate ketones= acidic)
Describe the pathogenesis of Type 1 Diabetes
-Genetic predisposition – HLA haplotypes (HLA-DR and HLA-DQ) as risk alleles
-Environmental trigger
=? viral infection
=? chemical toxin
-Autoimmune mechanism activated – can detect antibodies in blood to GAD, IA2 and/or ZnT8
-Destruction of pancreatic beta cells (cytotoxic lymphocytes)
Describe the development of Type 1 Diabetes
-Progressive destruction beta cells
-Can take many years
=Genetic susceptibility
=Insulitis, inflammatory cell infiltration
=Impaired glucose tolerance
What are the relative risk when relatives are diagnosed with Type 1 Diabetes?
- 0.5% lifetime risk
- Father= 9
- Mother= 3
- Non-HLA identical sibling= 3
- HLA-identical sibling= 16
- Non-identical twin= 20
- Identical twin= 35%
- Bother parents= 30%
Describe the prevalence of Type 1 Diabetes
-North-South Gradient in Europe
= More cases the further north
=Viruses in cold climates??
What autoimmune disorders are associated with Diabetes?
- Thyroid disease
- Pernicious anaemia
- Coeliac disease
- Addison’s disease
- Vitiligo
