Diabetes Mellitus

Diabetes Mellitus is a metabolic disorder in which the body does not produce enough insulin, or does not respond normally to insulin, leading to hyperglycaemia – abnormally high blood sugar level a.k.a. glucose. Causes include defects in insulin secretion, insulin action, and abnormal carbohydrate, fat, and protein metabolism.

Diabetes Mellitus Pathophysiology

  1. Food is ingested
  2. The pancreas produces LESS insulin than required
  3. High level of glucose is retained in the blood
  4. Breakdown of proteins and body fats lead to production of ketones, resulting in weightloss
  5. Excess glucose is excreted in urine, causing increased urine output and excessive thirst due to osmotic diuresis
  6. In case of very low insulin availability, accumulation of ketones result in ketoacidosis

Signs & Symptoms

  • polyuria – excessive urination
  • polydipsia – excessive thirst
  • polyphagia a.k.a. hyperphagia – excessive hunger due to cells being in a state of starvation
  • weightloss
  • fatigue
  • blurred vision
  • tingling and/or numbness in extremities – usually if diagnosed at a later stage, after peripheral nerve damage has already occurred
  • slow-healing wounds
  • recurrent infections – both women and men experiencing frequent infections should be tested for diabetes

NOTE: if uncontrolled, patient appears to be drowsy and may become unconscious; severe signs of diabetes include drowsiness and coma.

Diabetes Type 1 VS Diabetes Type 2

diabetes mellitus type 1 vs diabetes mellitus type 2
Retrieved from https://www.homage.sg/health/type-1-type-2-diabetes/ on 16th March 2022

Type 1 Diabetes

In Type 1 Diabetes there are very low levels of C-peptide in the blood or urine, which at times go undetected. Insulin becomes a requirement for survival. In the worst case scenario, the diabetic person may develop diabetic ketoacidosis (DKA) – a serious complication of diabetes that can be life-threatening. In DKA, the body undergoes an auto-immune process where it destroys beta cells, leading to lack of insulin production, making it impossible for blood sugar to enter the cells to be converted into energy. A person in DKA requires immediate acute care.

Type 1 Diabetes is not related to lifestyle factors, but to genetic predisposition and environmental factors.

Type 2 Diabetes

In Type 2 Diabetes, DKA can occur in stressful situations, although quite rare (since insulin is still produced even if in small amounts). Insulin is required as a controlling measure. Risks for Type 2 Diabetes include increasing age, obesity, unhealthy lifestyle, familial predisposition, and past gestational diabetes. This type of diabetes may remain undiagnosed for a long time.

gestational diabetes

Gestational Diabetes Mellitus (GDM) is diagnosed during pregnancy in the 2nd or 3rd trimester. Diagnosis criteria includes fasting plasma glucose of 5.1-6.9mmol/L OR 1 hour post-load plasma glucose of at least 10.0mmol/L OR 2 hour post-load plasma glucose of 8.5-11.0mmol/L.

LADA – Latent Autoimmune Diabetes in Adults

LADA a.k.a. slowly evolving immune-mediated diabetes is a hybrid form of diabetes which does not require insulin upon diagnosis, but which eventually does move on to needing insulin at a much faster rate than a person with Type 2 Diabetes. A person with LADA is usually over 35 years of age on diagnosis, testing positive for GAD auto-antibodies (antibodies to glutamic acid decarboxylase).

Ketosis-Prone Type 2 Diabetes

In this type of hybrid diabetes which typically affects young African-Americans, the person presents with severe insulin deficiency and ketosis.

Other Types of Diabetes

  • MONOGENIC DIABETES includes Neonatal Diabetes, and MODY (Maturity Onset Diabetes of the Young)
  • EXOCRINE PANCREATIC INSUFFICIENCY (EPI) include pancreatitis and cancer
  • DRUG-INDUCED DIABETES such as glucocorticoids
  • INFECTIONS such as cytomegalovirus
  • MONOGENIC DEFECTS OF INSULIN ACTION
  • ENDOCRINE DISORDERS such as Cushing’s Syndrome
  • GENETIC SYNDROMES such as Down’s Syndrome and Huntington’s Chorea
  • UNCLASSIFIED DIABETES

Criteria for Asymptomatic Prediabetes and Diabetes Mellitus Testing

Prediabetes is not considered as a clinical condition. Testing for prediabetes and diabetes in asymptomatic overweight or obese individuals is recommended for those with at least one of the following risk factors:

  • diabetic first-degree relative
  • ethnicity
  • history of cardiovascular disease
  • sedentary lifestyle
  • hypertension (including individuals on anti-hypertensives)
  • low HDL Cholesterol level and/or high triglyceride level
  • women with PCOS
  • conditions related to insulin-resistance
  • HIV

NOTES:

  • Individuals diagnosed with prediabetes should be re-tested for diabetes on a yearly basis
  • Women who have had Gestational Diabetes Mellitus should be re-tested for diabetes every 3 years
  • From the age of 35, every individual should start undergoing diabetes testing. Following a normal result, testing should be repeated after 3 years unless the person is considered to be high risk

Diabetes Mellitus Diagnosis

FASTING PLASMA GLUCOSE (FPG) – blood testing following an 8 hour fasting period (a test result of 7.0mmol/L / 126mg/dl or more indicates diabetes).

Patient should have the appointment scheduled early in the morning. Hypoglycaemics should NOT be administered whilst fasting. Patients on Lantus need to take their dose in the evening, without the bonus dose in the morning; they should then check their blood glucose before they leave in the morning to ensure they are not hypoglycaemic – if they are, they need to take something and reschedule their FPG test.

About 7ml of venous blood is drawn into a red or grey top tube. Patient should eat after FBG test.


ORAL GLUCOSE TOLERANCE TEST (OGTT) – blood testing following 75g oral glucose intake 2 hours before (a test result of 11.1mmol/l / 200mg/dl or more indicate diabetes).

Encourage patient to take full 75g dose since it is difficult to ingest. Smoking affects results so tell your patient to avoid smoking.

Prior to testing day, patient should consume adequate carbohydrate intake and perform physical activity, and should eat a 30-50g carbohydrate-based meal the evening before the test and fast for 8 hours, drinking water only if necessary. Drugs may be stopped based on physician’s recommendation. Patient’s weight should be measured to determine recommended oral glucose dose.

During test, a fasting blood specimen should be taken prior to administration of oral glucose – 75g carbohydrate load (patient can drink water if needed – no smoking). Blood is drawn after 2 hours. Patient should be monitored for transient reactions such as dizziness, sweating and weakness.

Note any drugs which can impact the result on the laboratory slip and send to the lab. Patient can drink and eat as normal, and if required, insulin or oral hypoglycaemic agents can be administered if prescribed.


HAEMOGLOBIN A1c (HbA1c) – average blood glucose level testing covering the previous two to three months (a test result of 6.5% / 48mmol/mol or more indicates diabetes)

NOTE: If asymptomatic, repeat the same test on a different day. Two test results above the threshold are required for diabetes diagnosis.

Prediabetes

Prediabetes refers to the phase in which the criteria for diabetes is not met, but the glucose levels are higher than normal. It is associated with obesity, high triglyceride level, low HDL cholesterol level, and hypertension.

Whilst prediabetes is not considered to be a clinical condition, it increases the risk for diabetes as well as cardiovascular disease, and so, individuals diagnosed with prediabetes should take preventative measures to avoid progressing to type 2 diabetes.

Prediabetes is determined by the following test results:

  • FPG 100mg/dl (5.6mmol/l) to 125mg/dl (6.9mmol/l) OR
  • 2hr PG during 75-g OGTT 140mg/dl (7.8mmol/l) to 199mg/dl (11.0mmol/l) OR
  • HbA1c 5.7-6.4% (39-47mmol/mol)

Diabetes Mellitus Nursing Care Management

Additional Notes…

  • blood glucose control may be lost when the patient is going through stress, exercise, puberty, fever, etc.
  • excessive thirst is a possible warning sign for diabetes
  • sense of smell is not affected in individuals with diabetes
  • individuals with diabetes can still eat foods high in carbs as long as they make adjustments in their medication doses (as instructed by their clinician)
  • frequent urination is a possible warning sign for diabetes
  • individuals with diabetes can still exercise
  • numbness in the hands and feet is common in individuals with diabetes
  • being overweight or obese doesn’t increase the risk of getting type 1 diabetes
  • individuals with diabetes can still enjoy some sweets or ice cream (in moderation)
  • diabetes is a life threatening condition – over a century ago, having diabetes without insulin treatment being available meant having a terminal illness

Reference

World Health Organization (2019). Classification of diabetes mellitus. Retrieved from https://apps.who.int/iris/rest/bitstreams/1233344/retrieve


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The Endocrine System – Pancreas Anatomy and Physiology

The pancreas, which is located in the curve of the duodenum, is a flat organ measuring between 12.5cm-15cm. It is a composite gland – both an exocrine and an endocrine gland: Exocrine acini secrete digestive enzymes into the duodenum, while the Islets of Langerhans help with carbohydrate metabolism.

pancreas anatomy and physiology
Retrieved from https://en.wikipedia.org/wiki/Pancreas on 7th March 2022

Pancreas Blood Supply

The Splenic Artery supplies the pancreas with blood, while venous return is completed through small veins within the Splenic Vein.

pancreas anatomy and physiology
Retrieved from https://epos.myesr.org/posterimage/esr/ecr2014/120564/mediagallery/539242?deliveroriginal=1 on 7th March 2022

Pancreas Nerve Supply

The Autonomic Nervous System (ANS) innervates the pancreas. Parasympathetic Vagal Fibres stimulate exocrine secretion, while Sympathetic Vasoconstrictor Impulses travel through nerves derived from spinal cord segments T6-T10 which pass through blood vessels within the pancreas. This reflects why pancreatic pain frequently radiates these nerve pathways.

pancreas anatomy and physiology
Retrieved from https://clinicalgate.com/thorax-2/ on 7th March 2022

The Endocrine Portion

The Islets of Langerhans contain 4 types of cells:

  1. Alpha Cells – make up 15% of the pancreatic islet cells; secrete Glucagon
  2. Beta Cells – make up 80% of the pancreatic islet cells; secrete Insulin
  3. Delta Cells – make up 5% of the pancreatic islet cells; secrete Somatostatin
  4. F Cells – secrete Pancreatic Polypeptide
Retrieved from https://slideplayer.com/slide/7426531/ on 7th March 2022
  • Glucagon INCREASES blood glucose level
  • Insulin DECREASES blood glucose level
  • Somatostatin INHIBITS insulin and glucagon, acting as a regulator
  • Pancreatic Polypeptide INHIBITS somatostatin secretion, gallbladder contraction, and digestive enzyme secretion (Pancreatic Polypeptide is secreted near the end of the digestive system)

Glucagon

The main function of glucagon is that of increasing blood glucose level. This is carried out through the following process:

  1. Glucagon increases glycogen conversion into glucose within the liver (glycogenolysis) AND increases nutrient (amino acids, glycerol and lactic acid) conversion into glucose within the liver (gluconeogenesis)
  2. Liver releases glucose into the blood, causing an increase in blood sugar level
  3. Blood sugar level controls secretion of glucagon through a negative feedback mechanism

lysis = breaking down of glycogen

neo = new

genesis = production

Secretion of glucagon is STIMULATED by:

  • decreased blood glucose level
  • protein-based foods
  • exercise

Secretion of glucagon is INHIBITED by:

  • somatostatin
  • insulin

Insulin

Islet beta cells produce insulin, which increases protein build-up within the cells. Insulin regulation is controlled by a negative feedback mechanism based on the blood sugar level.

Insulin decreases blood sugar level through the following process:

  1. increases glucose transportation from the blood into the cells
  2. increases glucose conversion into glycogen (glycogenesis)
  3. decreases glycogenolysis and gluconeogenesis
  4. stimulates glucose conversion to fatty acids
  5. stimulates protein synthesis

Secretion of insulin is STIMULATED by:

  • increased blood glucose level
  • acetylcholine (released by parasympathetic vagus nerve fibres)
  • amino acids (arginine and leucine)
  • growth hormone (GH) (which causes increase in blood sugar level)
  • ACTH (adrenocorticotropic hormone) (stimulates glucocorticoids secretion leading to hyperglycaemia, indirectly stimulating insulin release)

Secretion of insulin is INHIBITED by:

  • somatostatin (GIF – growth hormone inhibiting factor)

Insulin production is also AFFECTED by:

  • stomach and intestinal gastrin
  • secretin
  • cholecystokinin
  • gastric inhibitory peptide (GIP)

Insulin vs Glucagon

Somatostatin

Somatostatin is secreted by delta cells in the Islets of Langerhans following an increase in blood glucose, fatty acids, and amino acids due to an ingested meal. Somatostatin travels in the blood, slowing down the absorption of nutrients from the GIT, acting as paracrine secretion, diffusing into tissue fluid targeting nearby cells, and inhibiting both insulin and glucagon release from nearby alpha and beta cells.

Somatostatin secretion is INHIBITED by pancreatic polypeptide.

Pancreatic Polypeptide

Pancreatic Polypeptide inhibits secretion of somatostatin, gallbladder contraction, and secretion of pancreatic digestive enzymes.

Secretion of pacreatic polypeptide is STIMULATED by:

  • protein-containing meals
  • fasting
  • exercise
  • hypoglycaemia

Secretion of pancreatic polypeptide is INHIBITED by:

  • somatostatin
  • hyperglycaemia

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