Diabetes and Hypoglycaemia Flashcards Preview

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Flashcards in Diabetes and Hypoglycaemia Deck (41)
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What is glucose and how is it maintained? 


Glucose is the major energy substrate 

Its levels are maintained through 

  • Glycogenolysis 
  • Gluconeogenesis (lactose, amino acids and fatty acids are used to make glucose) 
  • Dietary Carbohydrates 


What is the livers role in terms of glucose levels? 

After meals → it will store glucose as glycogen 

During fasting → it will make glucose readily available through glycogenolysis and gluconeogenesis 


List two reasons why glucose levels must be regulated

Avoid Deficiency → brain and erythrocytes require a continous supply 

Avoid Excess → High glucose and metabolites cause pathological changes to tissue e.g. micro/macro vascular diseases, neuropathy 


What are the metabolic effects of insulin? 

  • Decreases ketogenesis
  • Decreases gluconeogenesis
  • Decreases glycogenolysis
  • Decreases lipolysis, increases lipogenesis 
  • Increases uptake of glucose into tissues
  • Increases amino acid uptake
  • Increases glycogen synthesis
  • Increased fatty acid synthesis 


What is the definition of diabetes mellitus? 

Metabolic disorder characterised by chronic hyperglycaemia, glycosuria and associated abnormalities of lipid and protein metabolism 

Hyperglycaemia is as a result of increased hepatic glucose production and decreased cellular glucose uptake 



When do you get glycosuria? 

When blood glucose > 10mmol/L exceeding renal threshold 


How do we diagnose for DM? 

  • In presence of symptoms (polyuria, polydipsia and weight loss for type 1) 
    • Random plasma glucose >11.1 mmol/l (200mg/dl)  
    • Fasting plasma glucose >7.0 mmol/l (126 mg/dl) (fasting is defined as no calorific intake for at least 8 hours)
    • Oral glucose tolerance test (OGTT) – plasma glucose > 11.1 mmol/l
      • Given glucose and check levels after a few hours
  • In the absence of symptoms
    • Test blood samples on 2 separate days


What is IGT and IFG? 

 Impaired glucose tolerance (IGT) → blood glucose is raised above normal levels but not enough to warrant diabetes. However you are at a greater risk of developing diabetes/ cardiovascular disease 

  • Fasting plasma glucose
  • OGTT value of 7.8-11.1 mmol

Impaired Fasting Glycaemia (IFG) → occurs when blood glucose levels in the body are elevated during fasting, but not enough to prompt diagnosis of diabetes 

  • Fasting plasma glucose and OGTT value <7.8


What is an oral glucose tolerance test? 

  • 75g of oral glucose and test after 2 hours
  • Blood samples collected at 0 and 120 mins after glucose
  • Subjects tested fasting after 3 days of normal diet containing at least 250g of carbohydrate


In what type of patients is the oral glucose tolerance test carried out in? 

  • IFG (impaired fasting glycaemia)
  • Unexplained glycosuria
  • Clinical features of diabetes with normal plasma glucose values
  • For the diagnosis of acromegaly 


How can the oral glucose tolerance test be used for diagnosis of acromegaly? 

  • Higher levels of blood glucose will prevent the release of GH 
  • In a patient with acromegaly there will still be high levels of GH following the oral glucose tolerance test 


What are the ways in which diabetes can be classfied? 

  • TYPE 1 = Insulin secretion is deficient due to autoimmune destruction of beta cells in the pancreas by T-cells 
  • TYPE 2 = Insulin secretion is retained but there is target organ resistance to its actions 
  • SECONDARY = Chronic pancreatitis, pancreatic surgery, secretion of antagonists 
  • GESTATIONAL = Occurs for first time in pregnancy 


Describe type 1 diabetes? 

  • Predominantly in children and young adults
  • Sudden onset (days/weeks)
  • Appearance of symptoms may be preceded by ‘prediabetic’ period of several months


What is the pathogenesis of type 1 diabetes? 

  • Commonest cause is autoimmune destruction of B-cells 
  • Strong link with human leukocyte antigen genes within the major histocompatabillity complex region on chromosome 16 
  • HLA class II cell surface will present itself as foreign and self-antigens to T-lymphocytes to initiate an autoimmune response

    • Circulating antibodies to various cells against 

  • Glutamic acid decarboxylase
  • Tyrosine-phosphatase-like molecule
  • Islet autoantigen


What is the most commonly detected antibody associated with type 1 DM? 

Islet cell antibody 


What occurs as a consequence of type 1 DM? 

Destruction of beta cells will cause hyperglycaemia due to deficiency of both insulin and amylin 


What is amylin? 

Amylin is a glucoregulatory peptide hormone that is co-secreted with insulin 

It lowers blood glucose by slowing gastric emptying and supressing glucagon output from pancreatic cells 


What are the metabolic complications of type 1 DM? 


What is the presentation of type 2 DM? 

  • Slow onset (months/years)
  • Patients middle aged/elderly – prevalence increases with age
  • Strong familiar incidence


What is the pathogenesis of type 2 DM? 

insulin resistance; β-cell dysfunction:

may be due to lifestyle factors - obesity, lack of exercise


Describe some metabolic complications of type 2 DM

  • Development of severe hyperglycaemia
  • Extreme dehydration
  • Increased plasma osmolality
  • Impaired consciousness
  • No ketosis
  • Death if untreated
  • Hyper-osmolar non-ketotic coma (HONK)



What can type 2 DM result in? 

Hyper-osmolar non-ketotic coma (HONK) will be ketoacidosis in type 1 DM


What is the treatment of type 2 DM? 

  • Initially you will have foods with a lower glycaemic index and carry out more exercise
  • If this does help, then diabetic drugs will be the next option of treatment
    • Metformin, sulphonylureas, dipeptidyl peptidase inhibitors (DPP-4) 


What does metformin do? 

Metformin will help increase uptake of glucose from blood and decrease gluconeogenesis


What do sulphonylureas do? 

Stimulate the cells of the pancreas to make more insulin and help insulin work more effectively


What do dipeptidyl peptidase inhibitors do? 

DPP-4 inhibitors work by blocking the action of DPP-4, an enzyme which destroys the hormone incretin.

Incretins help the body to produce more insulin only when it is needed and reduce the amount of glucose being produced by the liver when it is not needed 


How do you monitor glycaemic control? 

1. Self Monitoring

  • Capillary blood measurement 
  • Urine Analysis → Glucose in urine gives an indication of blood glucose concentration above the renal threshold 

2. 3-4 Months 

  • Blood HbA1c

3. Urinary albumin (index of risk progression to neuropathy) 


What is blood HbA1c? 

Glycated Hb; covalent linkage of glucose to residue in Hb 


What are long term complicatons of T1 and T2 diabetes? 

  • Micro-vascular disease:
    • Retinopathy, nephropathy, neuropathy
      • (glucose can damage blood vessels of the eye, nerve endings or nerves)
      • Patients with diabetes will require frequent eye checks
      • Amputations of leg can occur
  • Macro-vascular disease:
    • related to atherosclerosis heart attack/stroke


What are the responses of falling glucose levels in fasting? 

  • Physiological counter-regulatory response
    • Suppression of insulin release, limiting glucose entry into non-cerebral tissues
    • Secretion of glucagon, adrenaline, noradrenaline, cortisol and growth hormone to raise glucose level 

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