Acute Metabolic Complications of Diabetes

Slide 1 · Acute Metabolic

Complications of Diabetes

Diabetic ketoacidosis · Hyperosmolar hyperglycemic state · Hypoglycemia

Mechanistic pathology and clinicopathologic interpretation

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Connect insulin deficiency and counterregulation to acute metabolic derangements.

Trace the distinct mechanisms leading to ketoacidosis and hyperosmolar dehydration.

Recognize clinically important symptom patterns and precipitating conditions.

Differentiate the three emergencies and explain the therapeutic principles stated.

Mechanism → manifestation → clinical recognition

Slide 3 · Three emergencies, three dominant metabolic problems

Complication

Dominant disturbance

Characteristic consequence

Diabetic ketoacidosis

Insulin deficiency; excessive ketone-body production

Metabolic acidosis + dehydration

Hyperosmolar hyperglycemic state

Sustained severe hyperglycemia; water losses

Profound dehydration + altered mental status

Treatment-associated hypoglycemia

Glucose availability becomes inadequate

Autonomic and neurologic manifestations

Each has a distinct proximate mechanism; All warrant prompt recognition.

Slide 4 · Acute and chronic complications require different lenses

Acute metabolic complications reflect an immediate disruption of metabolic homeostasis.

Hyperglycemic crises can rapidly produce fluid loss and neurologic deterioration.

Treatment-associated hypoglycemia is an acute consequence of glucose-lowering therapy.

Chronic diabetic vascular injury is a separate topic, not the principal focus here.

The acute clinical question is what metabolic process is failing now.

Slide 5 · Insulin normally favors nutrient storage

Insulin is a major anabolic hormone regulating glucose, lipid, and protein metabolism.

Its action supports glucose assimilation by muscle and adipose tissue.

Insulin deficiency shifts metabolism toward mobilization of stored fuels.

Normal insulin action

Glucose use and fuel storage

Anabolic metabolic state

Slide 6 · Loss of insulin produces a catabolic shift

Peripheral glucose uptake falls when insulin action is markedly deficient.

Glycogen reserves become mobilized rather than replenished.

Fat and protein breakdown supply alternate circulating substrates.

The same hormonal disturbance can drive both hyperglycemia and ketogenesis.

Insulin deficiency

↓ glucose assimilation + ↑ fuel mobilization

Hyperglycemia and substrate release

Slide 7 · Counterregulatory signals intensify metabolic failure

Glucagon acts in opposition to insulin in the ketoacidotic state.

Stress-related epinephrine reduces residual insulin action and stimulates glucagon secretion.

These effects intensify the loss of metabolic restraint on glucose production.

Infection / trauma / illness

Epinephrine → reduced insulin action; ↑ glucagon

Exacerbated hyperglycemia

Slide 8 · Hyperglycemia begins a renal water-loss cascade

As plasma glucose rises, filtered glucose can exceed tubular reabsorption capacity.

Glucose then appears in urine (glycosuria).

Urinary glucose increases osmotic water loss, generating polyuria.

Continued diuresis progressively depletes water and electrolytes.

High blood glucose

Glycosuria

Osmotic diuresis

Water and electrolyte depletion

Slide 9 · Why dehydration amplifies the clinical problem

Prolonged polyuria creates a continuing deficit unless fluid intake replaces losses.

Dehydration compromises urinary clearance of circulating ketones in DKA.

In HHS, inability to compensate for water loss is especially important.

The resulting volume depletion is itself clinically consequential.

Osmotic urinary fluid losses

Replacement is inadequate

Progressive dehydration

Slide 10 · Two hyperglycemic pathways diverge at ketogenesis

Marked insulin deficiency

Unrestrained lipolysis

Ketone acids accumulate

DKA phenotype

Residual portal insulin

Ketogenesis relatively restrained

Prolonged osmotic diuresis

HHS phenotype

Slide 11 · Precipitating context directs the initial reasoning

Hyperglycemic deterioration

Missed insulin

Infection or severe stress

Insufficient water intake

Glucose-lowering therapy

Insulin or sulfonylurea

Missed meal or exertion

Excess dosing / misdosing

Slide 12 · Diabetic ketoacidosis: Linked hyperglycemia and acid production

DKA is a severe acute metabolic complication, encountered mainly in type 1 diabetes.

Insulin deficiency plus glucagon excess increase blood glucose and ketone production.

Osmotic diuresis and ketoacidosis jointly account for systemic illness.

Depressed consciousness and coma may follow persistent derangement.

Insulin deficiency + glucagon excess

Hyperglycemia + ketone-body overproduction

Dehydration + metabolic acidosis

Neurologic compromise

Slide 13 · Why type 1 diabetes is especially vulnerable

Progressive β-cell loss ultimately produces major insulin deficiency.

An intercurrent stress can abruptly increase insulin requirements.

When endogenous or administered insulin is insufficient, catabolism becomes unrestrained.

DKA may be a severe manifestation of this metabolic transition.

Declining β-cell insulin output

Stress raises insulin requirement

Relative/absolute insulin insufficiency

Risk of ketoacidosis

Slide 14 · DKA can also occur in type 2 diabetes

Type 2 diabetes usually retains more portal-vein insulin than type 1 disease.

This residual insulin can restrain hepatic fatty-acid oxidation and ketone formation.

Under especially severe stress, DKA nevertheless may develop in type 2 diabetes.

Diabetes subtype is therefore informative but not an absolute exclusion.

“Mainly type 1” does not mean “type 1 exclusively.”

Slide 15 · Insulin omission is an important DKA trigger

Failure to take insulin is described as a frequent precipitating event.

Reduced insulin signaling removes restraint on glucose production and lipolysis.

Clinical assessment must connect drug exposure with the metabolic process.

Addressing the trigger is necessary in addition to reversing the crisis.

Insulin omitted

Insulin effect falls

↑ hyperglycemia + ↑ ketogenesis

DKA risk

Slide 16 · Infection and tissue stress can precipitate DKA

Infection, other illness, trauma, and certain drugs are recognized precipitants.

Stress responses can increase secretion of epinephrine.

Epinephrine opposes residual insulin action and promotes glucagon release.

Metabolic demand may then exceed available insulin.

Infection / illness / trauma

Counterregulatory stress response

Reduced effective insulin + ↑ glucagon

Metabolic decompensation

Slide 17 · The insulin–glucagon imbalance has two glucose effects

Peripheral tissues

Less glucose assimilation

Circulating glucose remains elevated

Liver

Increased gluconeogenesis

Additional glucose enters blood

Slide 18 · Reduced glucose utilization is not the whole story

Hyperglycemia is not explained solely by failure of tissue glucose uptake.

Concurrent hepatic glucose production further increases plasma glucose.

The two processes operate simultaneously during severe insulin insufficiency.

This helps explain why DKA can evolve rapidly under superimposed stress.

↓ peripheral glucose use

↑ hepatic glucose output

Combined hyperglycemia

Slide 19 · Urinary glucose drives osmotic diuresis in DKA

Excess filtered glucose is not completely reclaimed by renal tubules.

Glycosuria retains osmotic solute within tubular fluid.

Increased urinary water loss produces polyuria and dehydration.

Loss of electrolytes accompanies this water loss.

Severe hyperglycemia

Renal glucose threshold exceeded

Glycosuria → osmotic diuresis

Water/electrolyte deficit

Slide 20 · DKA dehydration impairs ketone elimination

The kidney normally contributes to urinary excretion of ketones.

Dehydration can compromise that elimination pathway.

Continued ketone-body production then outstrips utilization and excretion.

The systemic acid burden becomes progressively greater.

Osmotic diuresis

Dehydration

Reduced urinary ketone clearance

Worsening ketoacidosis

Slide 21 · Insulin deficiency activates adipose lipid mobilization

In the deficient-insulin state, hormone-sensitive lipase activity increases.

Adipose triglyceride stores are broken down.

Circulating free fatty acids (FFAs) rise and reach the liver.

This supplies the substrate for hepatic ketone-body production.

Insulin deficiency

Hormone-sensitive lipase stimulated

Adipose fat breakdown

FFAs delivered to liver

Slide 22 · Free fatty acids enter a hepatic mitochondrial pathway

FFAs arriving at the liver are esterified to fatty acyl–coenzyme A.

Fatty acyl–CoA molecules are oxidized within hepatic mitochondria.

The pathway generates ketone bodies that enter the circulation.

Ketone-body output increases when the hormonal brake is lost.

Circulating FFAs

Hepatic fatty acyl–CoA

Mitochondrial oxidation

Ketone-body formation

Slide 23 · Two principal ketone acids are named

Acetoacetic acid

Produced during hepatic fatty-acid oxidation

Contributes to circulating ketone burden

β-Hydroxybutyric acid

Major accompanying ketone-body product

Contributes to metabolic acidosis

Slide 24 · Ketone production can exceed peripheral utilization

Tissues can utilize circulating ketone bodies as fuels.

When the liver synthesizes them faster than they are consumed, ketonemia develops.

Excess ketone bodies may also appear in urine (ketonuria).

Excess production is the central driver of the ketoacidotic state.

Hepatic ketone production rises

Production > peripheral utilization

Ketonemia ± ketonuria

Systemic acid accumulation

Slide 25 · Ketonemia and ketonuria are related, not identical

In circulation

Hepatic output exceeds utilization

Ketones accumulate in blood

In urine

Ketones are eliminated renally

Dehydration may compromise clearance

Slide 26 · Protein catabolism can further aggravate ketosis

Insulin deficiency also favors breakdown of body proteins.

Catabolism releases amino acids that can supply metabolic pathways.

Ketogenic amino acids aggravate the ketotic state.

The dysregulation affects carbohydrate, fat, and protein metabolism together.

Insulin-deficient catabolism

Protein breakdown

Ketogenic amino-acid contribution

Greater ketotic burden

Slide 27 · Two disturbances converge to produce serious DKA

Glucose pathway

Hyperglycemia

Glycosuria

Dehydration

Lipid pathway

Lipolysis

Ketone-body production

Metabolic ketoacidosis

Slide 28 · Fatigue in DKA reflects systemic metabolic derangement

Fatigue is a recognized presenting manifestation.

Hyperglycemia, dehydration, and the catabolic state evolve concurrently.

Fatigue is nonspecific and needs interpretation alongside other DKA features.

It should not be used in isolation to identify a hyperglycemic emergency.

Use constellations of findings, not a single symptom.

Slide 29 · Nausea and vomiting are DKA warning manifestations

Nausea and vomiting occur in the ketoacidotic syndrome.

They may complicate the ability to replace ongoing fluid losses.

Their presence can reinforce a dehydrating process already driven by glycosuria.

These symptoms with their relative absence in HHS.

Gastrointestinal symptoms belong to the DKA phenotype.

Slide 30 · Severe abdominal pain can accompany DKA

Severe abdominal pain is a characteristic potential manifestation.

It occurs with a systemic metabolic disturbance rather than requiring a separate named lesion.

The symptom is clinically important when paired with polyuria, dehydration, or deep breathing.

Differential evaluation still requires consideration of concurrent illnesses.

Abdominal pain does not exclude a primary metabolic emergency.

Slide 31 · Fruity breath odor is a bedside clue in DKA

A characteristic fruity odor among DKA manifestations.

It appears within the broader clinical pattern of exaggerated ketone metabolism.

It is a supportive clue rather than a standalone test.

The core diagnosis still concerns the underlying metabolic state.

A clue supports a mechanism; It does not substitute for assessment.

Slide 32 · Kussmaul breathing signals a severe metabolic pattern

DKA

Systemic metabolic ketoacidosis

Deep, labored breathing may be present

HHS

Ketoacidosis usually absent

Kussmaul breathing may therefore be absent

Slide 33 · Prolonged DKA can impair consciousness

Sustained ketoacidosis can lead to depressed consciousness.

Progression to coma is possible without reversal of the metabolic crisis.

The neurologic finding occurs in the context of systemic derangement.

It marks escalation beyond early symptoms such as fatigue or nausea.

Persistent ketoacidotic state

Systemic metabolic deterioration

Depressed consciousness

Coma

Slide 34 · Mechanistic reading of a DKA presentation

Fluid-loss signals

Polyuria / thirst

Dehydration

Possible mental-status decline

Ketone-acid signals

GI symptoms / fruity odor

Deep, labored breathing

Progressive ketoacidosis

Slide 35 · DKA reversal requires addressing several mechanisms

Insulin administration as necessary for reversal.

Metabolic acidosis must be corrected as part of treatment.

Precipitating conditions such as infection also require treatment.

Addressing only one factor risks leaving a driver of the syndrome unresolved.

Restore insulin action

Correct metabolic acidosis

Treat precipitating illness

Reverse metabolic crisis

Slide 36 · Teaching case: Missed insulin and acute deterioration

HYPOTHETICAL TEACHING SCENARIO

A person with established insulin-treated diabetes misses insulin doses.

An intercurrent infection is followed by polyuria, vomiting, and deep breathing.

Identify the common hormonal disturbance linking these findings.

Explain how the renal and hepatic pathways contribute differently.

Teaching interpretation (presenter notes): See discussion key

Slide 37 · Hyperosmolar hyperglycemic state: A dehydration-dominant crisis

HHS is described particularly in type 2 diabetes.

Sustained hyperglycemia causes continued osmotic diuresis.

Inadequate replacement of urinary water losses leads to severe dehydration.

Impaired mental status may be the presenting consequence.

Persistent severe hyperglycemia

Sustained osmotic diuresis

Severe water deficit

Mental-status impairment

Slide 38 · Residual portal insulin helps explain absent ketoacidosis

Patients with type 2 diabetes may retain higher portal-vein insulin levels.

This insulin restrains unrestricted hepatic fatty-acid oxidation.

Ketone-body formation is therefore more effectively limited.

Hyperglycemia can nonetheless become extremely severe.

Residual portal insulin

Hepatic fatty-acid oxidation restrained

Less ketone-body overproduction

Hyperglycemia may still progress

Slide 39 · Osmotic diuresis is sustained over time in HHS

Chronic or sustained hyperglycemia continuously exposes renal tubules to excess glucose.

Glycosuria drives ongoing loss of water in urine.

If oral water intake is inadequate, the deficit accumulates.

This explains why profound dehydration dominates HHS.

Sustained hyperglycemia

Ongoing glycosuria

Prolonged urinary water loss

Cumulative dehydration

Slide 40 · Failure to replace water loss is a central vulnerability

HHS is particularly associated with an inability to drink enough water.

Water replacement may be restricted by acute disability or intercurrent illness.

Physiologic urinary losses then exceed intake.

Clinical severity reflects the resulting progressive fluid deficit.

Osmotic water loss persists

Drinking fails to match loss

Dehydration worsens

Neurologic consequences

Slide 41 · HHS with an older, disabled patient

An older patient with diabetes and stroke or infection.

Neurologic disability or illness can prevent adequate access to drinking water.

This circumstance permits continuing glycosuric fluid depletion.

Age alone is not the mechanism: Inadequate water replacement is.

Interpret patient vulnerability through the water-balance mechanism.

Slide 42 · HHS may lack the early symptoms of ketoacidosis

In HHS, ketoacidosis is absent or much less prominent description.

Nausea, vomiting, and Kussmaul breathing may therefore be absent.

Without these alerts, medical attention may be delayed.

Late presentation is associated with severe dehydration and altered mental status.

Ketoacidosis-associated symptoms absent

Warning features less conspicuous

Delayed clinical presentation

Severe dehydration / mental impairment

Slide 43 · Hyperglycemia in HHS is usually more extreme

Textbook pattern

DKA

HHS

Typical glucose description

250–600 mg/dL

600–1200 mg/dL

Key accompanying disturbance

Ketoacidosis + dehydration

Profound dehydration; little/no ketoacidosis

Interpretation

Ranges may overlap

Do not classify by glucose alone

These are Robbins descriptive ranges, not formal diagnostic criteria.

Slide 44 · Neurologic impairment in HHS reflects crisis severity

Mental-status change is a defining clinical concern account.

It develops against a background of marked hyperglycemia and dehydration.

The absence of prominent ketoacidotic symptoms may conceal progression.

Altered consciousness is a warning of advanced hyperglycemic decompensation.

Hyperglycemia persists

Severe dehydration evolves

Mental-status deterioration

Slide 45 · DKA and HHS share a renal mechanism but differ in ketogenesis

Feature

DKA

HHS

Major substrate problem

Glucose + ketone acids

Glucose-driven fluid loss

Common diabetes association

Mainly type 1; sometimes type 2

Typically type 2

Ketogenesis

Unrestrained in severe insulin deficiency

Relatively restrained by portal insulin

Prominent manifestations

GI symptoms, fruity breath, Kussmaul

Dehydration, impaired mental status

Both involve glycosuric diuresis; Ketone-acid generation distinguishes them.

Slide 46 · Teaching case: Dehydration without classic acidotic symptoms

HYPOTHETICAL TEACHING SCENARIO

An older person with type 2 diabetes becomes ill and cannot maintain water intake.

Polyuria continues; Consciousness progressively deteriorates.

Prominent vomiting and deep labored breathing are not reported.

Explain why an HHS-type presentation is more plausible than classic DKA.

Teaching interpretation (presenter notes): See discussion key

Slide 47 · Hypoglycemia is a treatment-associated acute danger

Insulin therapy as a common context in both diabetes types.

Sulfonylurea therapy is another important context in type 2 diabetes.

The emergency is inadequate circulating glucose during glucose-lowering therapy.

Rapid correction is important to avoid neurologic injury.

Insulin / sulfonylurea exposure

Too much glucose-lowering effect for current needs

Hypoglycemia

Autonomic and neurologic symptoms

Slide 48 · A missed meal can precipitate hypoglycemia

Food intake may be lower than anticipated while medication action persists.

Missing a meal as a precipitating circumstance.

The relevant clue is a mismatch between glucose supply and glucose-lowering treatment.

History-taking should identify recent meals and drug use.

Meal omitted

Glucose availability reduced

Medication effect persists

Hypoglycemic symptoms

Slide 49 · Excessive physical exertion is a recognized trigger

Physical activity changes the balance between available fuel and its use.

Excessive exertion among causes of treatment-associated hypoglycemia.

The circumstances should be interpreted alongside insulin or sulfonylurea exposure.

The exercise history may explain an otherwise unexpected episode.

Unusually high exertion

Greater metabolic fuel demand

Treatment–fuel mismatch

Hypoglycemia

Slide 50 · Insulin overadministration or misdosing can be causal

Drug exposure

Insulin dose too high

Administration error / misdosing

Context

Meal not taken

Exertion greater than expected

Slide 51 · Autonomic symptoms can be early hypoglycemic clues

Sweating is among the warning symptoms in the Robbins account.

Palpitations and tachycardia are also characteristic findings.

Dizziness may accompany these symptoms.

Look for the medication and meal/activity context rather than treating each symptom alone.

Sweating + palpitations during glucose-lowering therapy require urgent consideration of hypoglycemia.

Slide 52 · Confusion identifies neurologic compromise

Confusion is among the listed hypoglycemic manifestations.

If low glucose persists, loss of consciousness may develop.

Neurologic deterioration is a central reason immediate reversal is necessary.

Presentation can vary among individuals and episodes.

Ongoing hypoglycemia

Confusion / neurologic dysfunction

Possible loss of consciousness

Slide 53 · Repeated episodes may obscure warning symptoms

Usual symptom pattern

Sweating / palpitations

Dizziness, then possible confusion

Hypoglycemia unawareness

Warning symptoms may be blunted

Neurologic impairment may appear first

Slide 54 · Rapid glucose delivery reverses the immediate problem

Urgent restoration of glucose availability.

Oral glucose and intravenous glucose are named means of reversal.

Prolonged untreated hypoglycemia can produce permanent neurologic damage.

Correction of the episode must be paired with recognition of the precipitating circumstance.

Recognize hypoglycemic syndrome

Prompt oral / intravenous glucose

Reverse glucose deficit

Reduce risk of neurologic injury

Slide 55 · Teaching case: Altered mental status after a missed meal

HYPOTHETICAL TEACHING SCENARIO

A person receiving insulin has skipped a meal.

Sweating and palpitations are followed by confusion.

Identify the acute disturbance and the most relevant precipitating clue.

Explain why prompt correction matters to neurologic outcome.

Teaching interpretation (presenter notes): See discussion key

Slide 56 · Three syndromes differ by clinical clues and mechanism

Clinical dimension

DKA

HHS

Hypoglycemia

Underlying disturbance

Insulin deficiency + ketone acids

Prolonged hyperglycemic diuresis

Excess glucose-lowering effect

Key context

Missed insulin / stress

Impaired water intake

Insulin / sulfonylurea + mismatch

Illustrative clues

Vomiting, abdominal pain, Kussmaul

Marked dehydration, mental decline

Sweating, palpitations, confusion

Major immediate risk

Acidosis / dehydration / coma

Severe dehydration / mental decline

Neurologic injury / unconsciousness

Interpret treatment history, water balance, and ketotic features together.

Slide 57 · Clinical reasoning: Choose the dominant mechanism

Hyperglycemic crises

DKA: Ketone-acid clues

HHS: Prolonged water-loss clues

Glucose deficit

Treatment or meal mismatch

Autonomic ± neurologic clues

Slide 58 · Three questions organize the emergency history

Has insulin been omitted, or has major illness increased insulin needs?

Has urine output remained high while access to water has been inadequate?

Has an insulin/sulfonylurea dose coincided with a missed meal or unusual exertion?

Which symptom cluster best matches the predicted metabolic mechanism?

History is most useful when it explains the causal sequence.

Slide 59 · Integrated mechanism summary

Initiating imbalance

Metabolic pathway

Clinical syndrome

Marked insulin deficiency + glucagon excess

↑ glucose production + ↑ lipolysis/ketones

DKA: dehydration and ketoacidosis

Sustained hyperglycemia; inadequate drinking

Persistent glycosuria → urinary water depletion

HHS: profound dehydration

Insulin or sulfonylurea action exceeds fuel supply

Circulating glucose falls

Hypoglycemia: autonomic/neurologic effects

Different biochemical pathways lead to distinct bedside patterns.

Slide 60 · Applied comparison: Three hypothetical presentations

HYPOTHETICAL TEACHING SCENARIO

Presentation A: Insulin omitted, infection, vomiting, and Kussmaul breathing.

Presentation B: Type 2 diabetes, restricted access to water, progressive mental decline.

Presentation C: Insulin-treated diabetes, missed meal, sweating, and confusion.

Name the dominant emergency in each and trace one key causal step.

Teaching interpretation (presenter notes): See discussion key

Slide 61 · High-yield synthesis

DKA: Insulin deficiency with glucagon excess promotes both hyperglycemia and ketone-acid formation.

HHS: Residual insulin restrains ketogenesis, but sustained glycosuria can cause severe dehydration.

Hypoglycemia: Insulin or sulfonylurea treatment becomes hazardous when exposure and available fuel are mismatched.

All three may impair consciousness; The preceding mechanism determines the appropriate interpretation.

Recognize the physiology—not just the label.

Slide 62 · Core source and scope

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. (2026).

Main coverage: ketoacidosis, hyperosmolar hyperglycemic state, and treatment-associated hypoglycemia.

Physiologic context: insulin deficiency, glycosuria, and the classic type 1 diabetes symptom triad.

This lecture emphasizes the textbook account; numeric glucose ranges are descriptions rather than formal diagnostic cutoffs.

Chapter/page mapping and content origin are recorded in speaker notes.