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 – The Adrenal Glands

The adrenal glands are small triangular-shaped structures located at the top of both kidneys. Their function is to produce hormones that help in the regulation of the metabolism, immune system, blood pressure, stress response, and more.

adrenal glands
Retrieved from https://www.jaypeedigital.com/book/9789350903025/chapter/ch16 on 12th March 2022

The adrenal glands, which are covered by an inner thick layer of connective tissue with an outer thin fibrous capsule, contain two sections:

  1. OUTER ADRENAL CORTEX – makes up the biggest part of the gland
  2. INNER ADRENAL MEDULLA – the core

The OUTER ADRENAL CORTEX is made up of 3 parts:

  1. Zona Glomerulosa – makes up 15% of the total volume (secretes mineralocorticoids)
  2. Zona Fasciculata – makes up the widest part of the total volume (mainly secretes glucocorticoids)
  3. Zona Reticularis – secretes amounts of hormones, mostly gonadocorticoids and androgens
adrenal glands
Retrieved from https://www.majordifferences.com/2014/04/difference-between-adrenal-cortex-and.html on 12th March 2022

Adrenal Cortex vs Adrenal Medulla

Mineralocorticoids

Mineralocorticoids are responsible for water and electrolyte homeostasis through control of sodium and potassium concentrations. 95% of all mineralocorticoid activity happens through Aldosterone:

  1. Aldosterone acts on the kidneys’ tubule cells, causing them to increase sodium reabsorption
  2. Sodium ions are removed from the urine and returned to the blood
  3. Rapid depletion of sodium from the body is prevented

Aldosterone causes:

  • potassium excretion
  • sodium reabsorption
  • hydrogen ions elimination
  • sodium, chloride, and bicarbonate ions retention
  • water retention

NOTE: Aldosterone reduces potassium reabsorption, thus, large potassium amounts are lost in urine excretion.

Electrolyte balance Secondary Effects

Sodium retention and potassium excretion lead to secondary effects:

  • Sodium reabsorption causes Hydrogen ions to pass into the urine to replace positive sodium ions, making the blood less acidic, thus preventing acidosis.
  • Sodium ions movement creates a positively charged field in the blood vessels surrounding the kidney tubules. This causes Chloride and Bicarbonate ions to move out from urine, back into the blood.
  • When ADH (antidiuretic hormone) is present, increased sodium concentration in the blood vessels causes water to move by osmosis from the urine into the blood.

Aldosterone control #1 – the raas system

RAAS system
Retrieved from https://www.pinterest.com/pin/557813103821299549/ on 13th March 2022

Aldosterone Control #2 – Potassium Ion Concentration

  1. Increased potassium concentration in extracellular fluid causes the adrenal cortex to secrete aldosterone
  2. Aldosterone secretion causes excess potassium to be eliminated by the kidneys
  3. Decreased potassium concentration in the extracellular fluid causes a decrease in aldosterone production, leading to less potassium excretion by the kidneys

Glucocorticoids

Glucocorticoids promote normal metabolism by:

  • increasing the rate of protein catabolism
  • increasing the rate at which amino acids are removed from cells and transported to the liver to undergo protein synthesis
  • releasing fatty acids from adipose tissue to be converted into glucose
  • promoting gluconeogenesis

Glucocorticoids promote stress resistance:

  • gluconeogenesis from amino acids causes a sudden increase in glucose availability, prompting the body to become more alert
  • blood vessels become more sensitive to chemicals that cause vasoconstriction so as to allow an increase in blood pressure

Glucocorticoids are anti-inflammatory compounds:

  • cause a reduction in mast cells
  • stabilise lyosomal membranes, leading to the inhibition of histamine release
  • decrease blood capillary permeability
  • depress phagocytosis by monocytes

Glucocorticoids:

  • Cortisol (hydrocortisone) – most abundant and responsible for about 95% of all glucocorticoid activity
  • Corticosterone
  • Cortisone

NOTE: Cortisol Serum blood test indicates adrenal function.

NOTE: Glucocorticoids slow down connective tissue regeneration, which leads to slow wound healing.

NOTE: Steroids are a synthetic form of glucocorticoids.

ACTH (Adrenocorticotropic hormone) Control

Glucocorticoid secretion is controlled through a negative feedback mechanism stimulated by stress and low blood glucocorticoid level:

  1. stress and low blood glucocorticoid level stimulate the hypothalamus to secrete CRF (corticotropin releasing factor)
  2. CRF secretion causes ACTH to be released from the anterior lobe of the pituitary
  3. ACTH is carried to the adrenal cortex, where it stimulates glucocorticoid secretion
adrenal glands
Retrieved from https://quizlet.com/279451837/chapter-9-vocabulary-flash-cards/ on 13th March 2022

Gonadocorticoids

The adrenal cortex is responsible for the secretion of both male and female sex hormones – oestrogens and androgens.

Adrenal Medulla

  • The adrenal medulla is made up of chromaffin cells (hormone-producing cells) surrounding sinuses containing blood
  • These chromaffin cells are considered to be postganglionic cells specialised in secretion
  • Preganglionic fibres pass directly into the chromaffin cells of the gland within the adrenal medulla
  • Secretion of hormones is controlled by the autonomic nervous system and innervation by preganglionic fibres that allows rapid response to a stimulus by the gland

Epinephrine and Norepinephrine

The adrenal medulla synthesises the following two hormones:

  • Epinephrine (adrenaline)
  • Norepinephrine (noradrenaline)

Epinephrine is stronger than norepinephrine. It:

  • increases the blood pressure by increasing the heart rate and constricting the blood vessels
  • increases respiration rate
  • dilates respiratory passageways
  • decreases digestion rate
  • increases muscular contraction efficiency
  • increases blood sugar level
  • stimulates cellular metabolism

However, both epinephrine and norepinephrine:

  • mimic the sympathetic nervous system – they are sympathomimetic
  • help in stress resistance

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