glucose regulation

Glucose Regulation

Process of maintaining blood glucose levels within a narrow range for continuous cellular energy.

Metabolism

Biochemical reactions in cells producing energy, repairing tissues, and sustaining life processes.

Role of Insulin at the Cellular Level

Acts as a key unlocking cells to allow glucose entry from the bloodstream.

Glycogenesis

The insulin-promoted conversion of excess glucose into stored glycogen in liver and muscles.

Liver Response to Fasting or Exercise

Breaks down stored glycogen to release glucose back into circulation for steady energy.

Catabolism

Energy-releasing metabolic reactions that break down complex molecules into simpler units.

Anabolism

Energy-consuming metabolic reactions that build complex molecules from simpler ones.

Role of the Hypothalamus in Metabolism

Connects neural and endocrine systems with the pituitary gland to regulate metabolic homeostasis.

Euglycemia: Fasting Blood Glucose

70-99 mg/dL.

Euglycemia: 2-Hour Postprandial

100-140 mg/dL.

Hyperglycemia: Fasting Blood Glucose

Greater than 100 mg/dL.

Hyperglycemia: 2-Hour Postprandial

Greater than 140 mg/dL.

Hypoglycemia (General Threshold)

Blood glucose less than 70 mg/dL.

Hypoglycemia: Level 1

Glucose ≥ 54 mg/dL and < 70 mg/dL.

Hypoglycemia: Level 2

Glucose < 54 mg/dL.

Hypoglycemia: Level 3

Severe neuroglycopenic impairment requiring assistance; may lead to seizures, coma, or death.

Insulin (Source Cells)

Pancreatic beta cells.

Insulin (Primary Function)

Lowers blood glucose by facilitating cellular glucose entry and promoting storage.

Insulin Peak and Duration

Peaks in 30-60 minutes and returns to baseline in 2-3 hours.

Glucagon (Source Cells)

Pancreatic alpha cells.

Glucagon (Primary Function)

Raises blood glucose by stimulating glycogenolysis and gluconeogenesis.

Glycogenolysis

Breakdown of stored liver glycogen into glucose.

Gluconeogenesis

Synthesis of glucose from non-carbohydrate precursors like lactate, amino acids, and glycerol.

Incretins

Intestinal peptides that enhance insulin secretion following food intake.

Somatostatin (Source & Function)

Secreted by pancreatic delta cells; inhibits insulin and glucagon release and slows gastric motility.

Ghrelin

Stomach-derived hormone that stimulates appetite via hypothalamic neurons.

Epinephrine (Metabolic Effect)

Released from adrenal medulla during SNS activation to rapidly increase blood glucose production.

Cortisol Secretion Pathway (HPA Axis)

Hypothalamus releases CRH → Anterior pituitary secretes ACTH → Adrenal cortex releases cortisol.

Cortisol (Metabolic Effect)

Raises blood glucose by promoting gluconeogenesis and inducing temporary insulin resistance.

Modifiable risk factors

- diet & lifestyle (High cal & carb, refined sugars, obesity)

- Cx stress

- smoking/pollutants

- ETOH use (inhibits gluconeogenesis)

Non-modifiable risk factors

- aging

- genetics

- race + ethnicity (AA, Hispanic, Native Americans, Asian)

- Gender (PCOS)

Medical triggers for DM

- infection and illness (insulin resistance)

- steroid meds (hyperglcemia)

- beta blockers (hypoglycemic s/s, leads to unawareness)

-diuretics (K+ loss = inhibition of insulin)

Negative Feedback Mechanism in Glucose Regulation

Rising glucose triggers insulin release; falling glucose inhibits insulin and stimulates glucagon.

Type 1 Diabetes Mellitus (T1DM) Etiology

Autoimmune destruction of pancreatic beta cells leading to absolute, lifelong insulin deficiency.

Type 2 Diabetes Mellitus (T2DM) Pathophysiology

Insulin resistance causes compensatory hyperinsulinemia, eventually leading to beta-cell failure and hyperglycemia.

Primary Target Tissues of Insulin Resistance in T2DM

Skeletal muscle, liver, and adipose tissue.

Beta-Cell Compensation in Early T2DM

Beta cells temporarily overproduce insulin to force glucose into insulin-resistant target cells.

Diabetic Ketoacidosis (DKA) Pathophysiology

Absolute insulin deficiency causing fat breakdown into acidic ketone bodies and metabolic acidosis.

DKA Diagnostic Criteria

Blood glucose > 250 mg/dL, metabolic acidosis (pH < 7.2), and severe dehydration. Ketones in urine

DKA Key Clinical Signs

Polyuria, thirst, abdominal pain, Kussmaul respirations, altered mental status, and fruity breath.

Kussmaul Respirations

Deep, rapid breathing mechanism to blow off acidic CO₂ during metabolic acidosis.

Hyperosmolar Hyperglycemic State (HHS) Pathophysiology

Severe hyperglycemia in T2DM from insulin resistance/insufficiency without significant ketosis or acidosis.

HHS Key Clinical Features

Extremely high glucose (500-700+ mg/dL), profound diuresis, intracellular dehydration, and altered consciousness.

HHS vs. DKA Mortality

HHS has higher mortality than DKA because its subtle onset delays clinical recognition.

Microvascular Complications of Hyperglycemia

- Retinopathy (blindness)

- nephropathy (renal failure)

- peripheral neuropathy (sensory loss)

Macrovascular Complications of Hyperglycemia

Accelerated atherogenesis causing coronary artery disease, stroke, and peripheral vascular disease.

Other Chronic Complications of Hyperglycemia

-High infection risk

-poor wound healing

-periodontal disease

-hypertension

-memory impairment

Effect of Hypoglycemia on the Central Nervous System

Glucose starvation of CNS cells leads to immediate neurologic dysfunction.

Early Signs of Hypoglycemia (Autonomic / Sympathetic)

-Palpitations

-tremors

-anxiety

-sweating

-pallor

-intense hunger

Late Signs of Hypoglycemia (Neuroglycopenic)

-Drowsiness

-confusion

-fatigue

-slurred speech

-unresponsiveness

-seizures

-coma

-death

Hypoglycemic Unawareness (Glycemic Unawareness)

Autonomic neuropathy blocks epinephrine release, preventing early warning signs before sudden loss of consciousness.

Subjective Assessment: Review of Systems (Three P's)

Polydipsia, polyuria, and polyphagia.

Subjective Assessment: Common Symptoms

Chronic fatigue, unexplained weight changes, slow-healing sores, and sensory changes (numbness/tingling).

Medication History: Compliance Barriers

Side effects like metformin-induced diarrhea causing patients to discontinue medication.

Psychosocial Assessment: Occupational Safety

Evaluating fall risks in patients with peripheral neuropathy working high-risk jobs.

Acanthosis Nigricans (Clinical Significance)

Key physical marker indicating severe insulin resistance in Type 2 Diabetes.

Fasting Plasma Glucose (FPG) Diagnostic Criterion

≥ 126 mg/dL after a minimum 8-hour fast.

Glycosylated Hemoglobin (HbA1c) Diagnostic Criterion

≥ 6.5%, reflecting average blood glucose over the preceding 2 to 3 months.

Oral Glucose Tolerance Test (OGTT) Diagnostic Criterion

≥ 200 mg/dL measured 2 hours after ingesting a 75g glucose solution.

C-Peptide Levels (Clinical Significance)

Indicates pancreatic beta-cell function; helps differentiate T1DM (low/absent) from T2DM.

Autoimmune Markers in Diabetes Diagnosis

Antibodies confirming autoimmune-mediated beta-cell destruction in T1DM versus idiopathic T1DM.

Serum Potassium Management in DKA

Must monitor and correct before insulin therapy to prevent severe hypokalemia as K+ enters cells.

Blood and Urine Ketone Monitoring

Essential for diagnosing DKA and monitoring its clinical resolution.

BMP and Urinalysis in Diabetes Monitoring

Evaluates renal function (BUN, creatinine, microalbuminuria) to screen for diabetic nephropathy.

Lipid Profile in Diabetes

Measures cholesterol, HDL, and triglycerides to assess macrovascular and cardiovascular risk.

Primary Prevention in Diabetes

-Family education

-low-sugar diet

-30-60 minutes daily exercise

-obesity prevention

Secondary Prevention in Diabetes

-Screening at age 45

-catching prediabetes early

-metformin therapy

-small habit stacking

Tertiary Prevention (Collaborative Care & Complication Management)

-Managing DM via insulin

-oral medications

-school Individualized Education Plans

DKA and HHS protocols

1. Aggressive fluid resuscitation: IV bolus of 1L isotonic fluid over 30 min - 1 hr (restores vascular volume)

2. Correction of K+ (needs to be corrected before starting insulin infusion, prevent hypokalemia)

Comprehensive Complication Screenings

Annual dilated eye exams, regular professional foot exams, and required vaccinations to prevent infection.

Interdisciplinary Team Approach in Diabetes

Involves dietitians, diabetes educators, exercise physiologists, behavioral specialists, and case managers.

Neuro-Regulation of Glucose Homeostasis

The central nervous system and hypothalamus act as primary regulators of hormonal homeostasis.

Effect of Severe Hypoglycemia on Brain Cells

Energy deprivation rapidly impairs cognitive function, potentially causing seizures, coma, or death.

Hyperglycemia Effect on Fluid & Electrolytes

Increases blood osmolality, pulling fluid into vascular space and causing osmotic diuresis.

Potassium Shift in DKA

Acidosis and insulin deficiency shift potassium into bloodstream, which reverses upon insulin administration.

Diuretic Effect on Beta Cells

Diuretic-induced potassium depletion directly impairs pancreatic beta-cell insulin secretion.

Perfusion Damage from Chronic Hyperglycemia

Vascular damage and atherogenesis lead to CAD, stroke, arterial ulcers, and amputations.

Elimination Complications of Autonomic Neuropathy

Nerve damage causes gastroparesis, severe bowel elimination issues, and neurogenic bladder.

Skin Integrity Signs in Insulin Resistance

Velvety skin thickening (acanthosis nigricans) and impaired wound healing with chronic ulcers.

Sensory Perception Loss in Diabetes

Peripheral neuropathy impairs sensation in hands and feet, risking deep infected ulcers.

Abdominal Pain in Acute DKA

Metabolic acidosis and severe dehydration produce sharp, distressing abdominal pain.

T1DM Primary Pathophysiology

Autoimmune destruction of pancreatic beta cells causing absolute insulin deficiency.

T2DM Primary Pathophysiology

Insulin resistance with gradual decline in beta-cell insulin secretion.

T1DM Typical Age of Onset

Often diagnosed in children and young adults under age 30.

T2DM Typical Age of Onset

Typically diagnosed in adults, though pediatric cases are rising rapidly.

T1DM Lifetime Insulin Requirement

Exogenous insulin is a strict lifetime requirement; oral hypoglycemics do not work.

T2DM Lifetime Insulin Requirement

Lifestyle and oral meds first-line; insulin added if beta cells fail.

T1DM Acute Complication Risk

High risk for Diabetic Ketoacidosis (DKA).

T2DM Acute Complication Risk

High risk for Hyperosmolar Hyperglycemic State (HHS).

T1DM Co-occurring Conditions

Strong autoimmune links with high rates of celiac and thyroid disease.

T2DM Co-occurring Conditions

Strongly associated with Metabolic Syndrome (obesity, HTN, dyslipidemia).