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
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
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
What is the clinical presentation of Type 1 diabetes?
Hyperglycaemia
Weight loss
Diabetic ketoacidosis
Fruity smelly breath/acetone
Fatigue, polyuria and polydipsia
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.
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 T cells back into the pancreas.
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.
What symptoms are associated with LADA?
Polydipsia, polyuria, weight loss, visual changes and neuropathic symptoms
What should be avoided in the management of LADA?
Sulphonylureas, as they worsen pancreatic beta cell function.
-> LADA has a risk of cardiovascular disease and small fibre neuropathy.
What is Mature Onset Diabetes of the Young (MODY)?
An autosomal dominant condition due to a monogenic mutation disrupting pancreatic beta cell function.
What is the most common mutation associated with MODY?
MODY3, due to a mutation of Hepatocytes nuclear factor 1 which is found in liver, pancreas and intestine. It is involved in pancreatic beta cell maturation, mitchochondrial metabolism and insulin secretion, causing a decreased renal threshold for glycosuria. It can lead to vascular complications and risk of metabolic Syndrome.
There is also a mutation of glucokinase, which can at as a sensor of glucose for pancreatic beta cells to stimulate insulin release.
What characterizes MODY2?
Only experiences mild hyperglycaemia, requiring lifestyle and dietary modifications
What is the most common medication prescribed for young people with MODY?
Metformin and sulphonylurea
What are the key features of MODY?
Family history of diabetes, patient does not necessarily require insulin, diagnosis under 25 years old
Which substance inhibits ketogenesis?
Insulin.
What is diabetic ketoacidosis (DKA)?
Most common complication in Type 1 diabetes with acute onset due to inability to use glucose as energy source. This stimulates liver cells to induce the uptake of fatty acids for beta-oxidation to form ketones which build up and raise blood pH. Ketones will be above 3 and ph will be below 7.3. The body tries to compensate by increasing breathing to get rid of CO2, causing shortness of breath and Kussmaul breathing. Patients present with Hypovolemia, hypotension, Kussmaul breathing and hyperglycaemia.
How do patients present with diabetic ketoacidosis?
Patients present with Hypovolemia, hypotension, Kussmaul breathing and hyperglycaemia. They progress from polyuria to volume depletion, with decreased urine output, skin turgor and sweating.
There is hyperkalemia due to shift in potassium from intracellular space to extracellular space due to insulin deficiency and hyperglycaemia.
What is the criteria for diagnosis of diabetic ketoacidosis?
Arterial ph below 7.3, serum bicarbonate less than 15 and hyperglycaemia.
Why does diabetic ketoacidosis occur?
DKA occurs with:
incorrect insulin management or non-compliance
Pancreatitis
Acute illness such as infection (pneumonia and UTI) trauma and surgery
Alcohol abuse and myocardial infarction
SGLT2 inhibitors
Why do SGLT2 inhibitors cause diabetic ketoacidosis?
SLGT2 inhibitors like canagliflozin have a diuretic effect and loss of glucose, promote glucagon secretion and stimulating ketogenesis to compensate.