Diabetes Flashcards
What is the normal range for plasma glucose?
Between 3.9 mmol/L and 5.6 mmol/L
What is the normal range for venous glucose?
Between 4 mmol/L and 6 mmol/L
What is an indicator for insulin release?
C-peptides which are important for correct folding of insulin and released with insulin by pancreatic beta cells. This can indicate B cell functioning
What are the criteria for diagnosing diabetes according to WHO 2006?
Must have diabetes symptoms and either:
* Random venous glucose of 11.1 mmol/L or more
* Fasting blood glucose over 7.1 mmol/L
* Two-hour plasma glucose over 11.1 mmol/L
Evidence from at least two tests must be on two separate days
What are the diagnostic criteria for gestational diabetes?
Fasting glucose over 5.6 mmol/L and 2-hour glucose over 7.8 mmol/Ll
What is the cutoff point for HbA1c?
Over 48 mmol/L; however it is not used by WHO for diagnosis of diabetes
In which populations is HbA1c not appropriate for diagnosing diabetes?
Children and young people
Type 1 diabetics
Acutely ill patients
Those with acute pancreatic damage
What conditions can make HbA1c levels inaccurate?
Anaemia
Medications predisposed to hyperglycaemia suc as steroids
Pregnancy
Patients on haemodialysis due to high glucose levels of dialysate fluid
What investigations are included for diabetes?
Estimated glomerular filtration rate, lipid profile, serum creatinine, sensation testing
What is the cause of Type 1 diabetes?
Autoimmune cell-mediated destruction of beta cells that prevents peripheral uptake of glucose due to
Genetic conditions associated with HLA-DR3 and HLA-DR4
Environmental triggers
Autoimmunity
How is insulin released from the pancreas?
Biphasic manner, where the first phase is a brief spike lasting 10 mins and the second has a longer plateau.
Which HLA markers are associated with Type 1 diabetes?
HLA-DR3 (Coeliacs) and HLA-DR4 (Hashimoto’s disease)
What is the autoantigen associated with Type 1 diabetes?
-> Glutamate decarboxylase (GAD65) is the most common
-> Islet cell cyptoplasm
-> Insulin
What are some environmental triggers for Type 1 diabetes?
Infectious agents such as cytomegalovirus, enterovirus, influenza, mumps and rubella
Childhood vaccination
Vitamin D deficiency
Short breastfeeding time
Obstetric complications
Childhood obesity
Psychological stress
What is the clinical presentation of Type 1 diabetes?
Duration of symptoms occur over a few weeks:
Hyperglycaemia
Weight loss
Diabetic ketoacidosis
Fruity smelly breath/acetone
Fatigue, polyuria and polydipsia
Incidence is typically childhood and adolescence
What characterizes Stage 1 of Type 1 diabetes?
Asymptomatic with normal fasting glucose and presence of 2 pancreatic autoantibodies. Beta cell death overwhelms phagocytes and causes buildup in pancreas, reducing first phase insulin release.
What characterizes Stage 2 of Type 1 diabetes?
Asymptomatic with dysglycaemia, raised HbA1c between 5.7 to 6.4, impaired glucose tolerance. There will be auto activation of B and T cells in the pancreatic lymph nodes.
What characterizes Stage 3 of Type 1 diabetes?
Symptomatic hyperglycaemia, polydipsia, polyuria, unintentional weight loss. There is movement of auto reactive B and CD4 and CD8 T cells back into the pancreas isley
Why is screening recommended for first or second-degree relatives of Type 1 diabetics?
Due to the heritability of autoimmune disease
What are common features of both Type 1 and Type 2 diabetes?
Polydipsia, polyphagia, polyuria due to glucose being a highly osmotic diuretic that draws water out of the nephrons into the urine.
What causes Type 2 diabetes?
Defective insulin secretion of pancreatic B cells and insulin insensitivity which reduces peripheral glucose uptake, associated with metabolic syndrome.
What are the features of metabolic syndrome?
Low HDL, high LDL, VLDL, and waist circumference
What happens when glucose levels are high in pancreatic beta cells?
B cells take up glucose from the GLUT2 receptor, undergo glycolysis, causing a rise in ATP which inhibits the K+ channel to prevent K+ efflux. This rise in intracellular K+ causes opening of Ca2”+ channels for Ca2+ influx that causes the release of insulin vesicles.
B cells synthesise pre-proinsulin, which undergoes a maturation process to pro insulin by the endoplasmic reticulum, and trnaslocated into vesicles of insulin in the Golgi apparatus, which are triggered to be released by high blood glucose.
What is Late Autoimmune Diabetes (LADA)?
Diabetes onset after age 30, associated with autoantibodies against islet B cells. It shares lifestyle risk factors with type 2 diabetes such as excess body weight, heavy smoking and intake of high carb food. Risk factors for LADA include autoimmune disease and low birth weight.
Patients with LADA may have hyperglycaemia for over 6 months without the need for insulin.