Diabetic Lipolysis & Ketoacidosis

Glucose Unavailability ➜ Shift to Alternative Fuels

• CONTEXTUAL RECALL (ties to previous lectures)

  • In untreated/poorly-treated diabetes mellitus, insulin either lacks or is ineffective.

  • Without sufficient insulin, cells cannot transport glucose across their membranes ("cells can’t use it").

  • Body reacts by mobilising stored energy: lipolysis (breakdown of triglycerides in adipose tissue).

• Lipolysis basics

  • Hormone-sensitive lipase hydrolyses triglycerides → glycerol + free fatty acids (FFAs).

  • FFAs enter blood and are delivered to liver & other tissues to be oxidised for ATP production.

  • While it supplies energy, it creates multiple downstream complications.

Immediate Biochemical & Circulatory Consequences

• Hyperlipidaemia

  • Transcript: “you get a whole bunch of fat in your bloodstream”.

  • Plasma FFA & VLDL concentrations rise.

  • Blood becomes more viscous; lipids can precipitate/accumulate along vascular endothelium.

• Organ-specific damage pathways

  • Heart ➜ Accelerated atherosclerosis → ↑ risk of coronary artery disease (CAD).

  • Kidneys ➜ Lipid deposits + haemodynamic changes raise intraglomerular pressure → diabetic nephropathy progression.

  • Eyes ➜ Fragile retinal vessels may rupture under lipid-induced hypertension → haemorrhage & visual loss.

"Good" & Bad of Burning Fat

• Superficial benefit: Weight loss (“yay”).

  • Often misperceived as positive; transcript emphasises it is not worth the trade-off.

• Hidden cost: generation of ketone bodies (acetoacetate, β-hydroxybutyrate, and acetone).

  • Produced in liver mitochondria from excess acetyl-CoA derived from FFA β-oxidation.

Ketoacidosis – Pathophysiology & Chemistry

• Chemical relationship
  $\text{Fatty Acids} \xrightarrow[\text{β-oxidation}]{} \text{Acetyl-CoA} \xrightarrow[\text{ketogenesis}]{} \text{Ketone Bodies}$

• Acid–base impact

  • Ketone bodies dissociate, releasing $H^+$ ➜ metabolic acidosis.

  • Normal arterial pH: $7.35!\text{–}!7.45$; Diabetic ketoacidosis (DKA) often < $7.30$.

  • “Low pH of the blood” = life-threatening.

Respiratory Compensation (Kussmaul Breathing)

• Acidic pH stimulates peripheral/central chemoreceptors.

• Leads to deep, laboured hyperventilation to reduce $CO_2$ (a volatile acid) and raise pH.

• Clinicians can suspect DKA purely from this breathing pattern (“doctor saw the way they were breathing”).

Acetone Breath & Forensic / Legal Misinterpretations

• One ketone (acetone) is volatile → exhaled air smells fruity/"nail-polish"-like.

• Real-world scenario: Law-enforcement officers may confuse acetone breath with ethanol intoxication → arrests for drunk driving.

• Explains need for medical rather than punitive response; underscores importance of glucometer checks in field sobriety contexts.

Neurological & Behavioural Manifestations

• Acidic pH and hyperosmolar state alter neuronal function.

  • Leads to confusion, disorientation, ataxia (“staggering around”).

  • Mimics alcohol inebriation, reinforcing misdiagnosis.

Cardiovascular & Systemic Dangers

• Arrhythmias: Acidosis affects ion channels; K⁺ shifts extracellularly → risk of ventricular fibrillation.

• Gastrointestinal: Nausea & vomiting exacerbate dehydration & electrolyte loss.

• Terminal progression: If untreated → cerebral oedema, coma, death (“ultimately causes it”).

Ethical & Practical Implications

• Medical-legal: Need for police, EMTs, and clinicians to distinguish DKA from intoxication to avoid wrongful arrest & ensure prompt care.

• Public health: Education on recognising DKA signs (weight loss, fruity breath, deep breathing) can save lives.

• Therapeutic: While ketogenic diets are popular, pathological ketogenesis in insulin deficiency is NOT equivalent; patient education is critical.

Consolidated Key Points for Review

• Insulin absence → cells starve despite hyperglycaemia.

• Body compensates by lipolysis → hyperlipidaemia & weight loss.

• Excess fatty-acid oxidation in liver produces ketone bodies.

• Ketone accumulation lowers blood pH → diabetic ketoacidosis (DKA).

• Clinical triad of DKA

  1. Metabolic acidosis (pH < $7.30$, serum bicarbonate < $18\,\text{mEq/L}$)

  2. Hyperglycaemia (glucose often > $250\,\text{mg/dL}$)

  3. Ketonaemia/ketonuria

• Kussmaul breathing + fruity breath are compensatory & diagnostic clues.

• DKA can mimic alcohol intoxication → risk of misdiagnosis/arrest.

• Immediate dangers: arrhythmias, cerebral dysfunction, coma, fatality.

Mnemonic

"FAT-BREATH"
F – Free fatty acids rise
A – Arrhythmias risk
T – Triglyceride overflow (hyperlipidaemia)
B – Breathing deep (Kussmaul)
R – Retinal bleeding
E – Electolyte shifts
A – Acetone aroma
T – Tachycardia ➜ CAD risk
H – High mortality if untreated