Lesson
Glucose Homeostasis and Disease Mechanisms
Glucose concentration reflects coordinated production, uptake, storage, counterregulation, renal handling, food, activity, illness, sleep, and medication. Diabetes emerges through different failures within this network.
- Beta-cell insulin
- Alpha-cell glucagon
- Liver and muscle
- Incretin and kidney
- Insulin resistance and beta-cell decline
Glycogenolysis and gluconeogenesis preserve fuel during fasting
Insulin, glucagon, and incretin signals respond to nutrient state
Uptake, storage, and restrained lipolysis limit circulating glucose
Coordinate fasting and fed physiology
In the fed state, glucose-stimulated insulin suppresses hepatic glucose production, promotes muscle and adipose uptake, supports glycogen and lipid storage, and restrains lipolysis and ketogenesis. During fasting, lower insulin and higher glucagon, catecholamines, cortisol, and growth hormone support glycogenolysis, gluconeogenesis, lipolysis, and fuel availability. Disease and treatment alter this balance over hours and years.
Trace organ contributions
The liver stores and releases glucose, skeletal muscle is a major site of insulin-mediated disposal, adipose tissue controls free fatty acid flux and inflammatory signaling, the kidney filters and reabsorbs glucose and contributes to gluconeogenesis, and the brain coordinates appetite and autonomic responses. Gut incretin hormones amplify glucose-dependent insulin release and affect glucagon, gastric emptying, satiety, and weight.
Separate insulin deficiency from resistance
Type 1 diabetes usually reflects autoimmune beta-cell destruction and progressive absolute insulin deficiency. Type 2 diabetes combines insulin resistance with a progressive inability of beta cells to meet demand. Glucotoxicity and lipotoxicity can further impair secretion and action, so severe hyperglycemia can temporarily blur phenotype and improve after metabolic stabilization.
Connect chronic hyperglycemia to tissue injury
Persistent hyperglycemia promotes glycation, oxidative stress, inflammation, endothelial dysfunction, altered cellular signaling, and microvascular injury. Duration, blood pressure, lipids, tobacco, kidney function, genetics, social conditions, and treatment access shape the observed risk. Glucose control is essential, but it is only one part of complication prevention.
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Lesson
Diagnosis and Classification
A laboratory threshold establishes diabetes, but the phenotype determines therapy and prognosis. Confirmation, assay validity, clinical urgency, and uncertainty must remain visible.
- Diagnostic thresholds
- Confirmatory testing
- Prediabetes
- A1C limitations
- Phenotype and etiology
A1C, fasting glucose, oral glucose tolerance, or symptomatic random glucose
Repeat unless symptoms or crisis make hyperglycemia unequivocal
Tempo, ketosis, antibodies, C-peptide, family history, and exposures
Apply the four diagnostic pathways
Diabetes is diagnosed by A1C at least 6.5 percent, fasting plasma glucose at least 126 mg/dL, two-hour plasma glucose at least 200 mg/dL during a 75 g oral glucose tolerance test, or random plasma glucose at least 200 mg/dL with classic hyperglycemic symptoms or crisis. Use a certified laboratory method. A glucose meter or CGM is not the diagnostic standard.
Confirm unless hyperglycemia is unequivocal
Without classic symptoms or crisis, obtain two abnormal results, either from the same sample using different tests or from repeat testing. When tests disagree, repeat the test above the diagnostic threshold and investigate substantial discordance. Prediabetes includes A1C 5.7 to 6.4 percent, fasting glucose 100 to 125 mg/dL, or two-hour glucose 140 to 199 mg/dL.
Know when A1C can mislead
A1C estimates chronic glycemia through red-cell exposure and can be distorted by altered red-cell turnover, hemoglobin variants, transfusion, pregnancy, kidney disease, erythropoietin, blood loss, iron status, and assay interference. Use plasma glucose for diagnosis when the A1C and glucose relationship is unreliable. Fructosamine or glycated albumin can support monitoring in selected contexts but have their own limitations.
Classify beyond type 1 and type 2
Consider autoimmune type 1 diabetes at any age, type 2 diabetes, monogenic diabetes, exocrine pancreatic disease, cystic fibrosis-related diabetes, medication or chemical effects, endocrinopathy, transplant, and gestational diabetes. Islet autoantibodies and C-peptide can clarify uncertain cases when interpreted with disease duration, glucose, kidney function, and recent insulin exposure. Classification may evolve over time.
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Lesson
Glycemic Assessment and Individualized Targets
A1C and CGM metrics answer different questions. Targets should reduce long-term injury without creating hypoglycemia, treatment burden, or loss of function.
- A1C interpretation
- Time in range
- Time below range
- Target individualization
- Reassessment and deintensification
Longer-term glycemic exposure interpreted through red-cell biology
Time in range, above range, below range, and variability
Hypoglycemia, function, burden, comorbidity, and personal priorities
Use A1C as an integrated exposure marker
For many nonpregnant adults, an A1C below 7 percent is appropriate when it can be achieved without severe or burdensome hypoglycemia. A lower goal can fit a healthy person with low treatment risk, while a less stringent goal can fit frailty, cognitive or functional limitation, severe comorbidity, limited life expectancy, or high treatment burden. Avoid symptomatic hyperglycemia in every group.
Add time and direction through CGM
For many nonpregnant adults using CGM, a goal above 70 percent time from 70 to 180 mg/dL is appropriate. Time below 70 mg/dL should generally remain below 4 percent and time below 54 mg/dL below 1 percent, with tighter hypoglycemia protection for many older or high-risk adults. Time above range, glucose management indicator, and coefficient of variation complete the pattern.
Reconcile discordant metrics
A1C can disagree with CGM because of red-cell biology, recent change, data gaps, device accuracy, glycemic variability, or the period each measure reflects. Do not average away discordance. Verify dates, wear time, calibration or confirmation needs, anemia and kidney context, recent therapy, and whether severe highs and lows yield a deceptively acceptable mean.
Treat deintensification as active safety
Reassess goals and reduce insulin, sulfonylurea, meglitinide, or other treatment burden when hypoglycemia, frailty, cognitive change, reduced intake, kidney decline, or limited benefit changes the balance. Deintensification is not abandonment. It is a deliberate strategy to preserve safety within meaningful goals.
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Lesson
Blood Glucose and Continuous Glucose Monitoring
A glucose device is useful only when the reading is accurate, interpreted in context, and connected to a safe decision. Data volume does not replace education.
- BGM accuracy
- CGM types and lag
- Ambulatory glucose profile
- Trend-based decisions
- Training and access
Technique, device limits, wear time, and confirmatory testing
Review lows first, then range, highs, variability, and repeated timing
Connect the pattern to food, activity, illness, medication, or access
Preserve blood glucose monitoring as a safety tool
People using CGM still need access to a blood glucose meter. Confirm CGM when symptoms do not match, the value changes rapidly, device performance is uncertain, or the system instructs confirmation. Use approved meters and correctly stored, unexpired strips. Hand contamination, poor perfusion, hematocrit, temperature, altitude, and interfering substances can affect readings.
Understand what CGM measures
CGM measures interstitial glucose rather than plasma glucose and can lag during rapid change. Real-time, intermittently scanned, professional, implanted, and over-the-counter systems differ in alarms, visibility, indication, duration, and integration. Sensor placement, compression, adhesion, warm-up, medication interference, data gaps, and alert fatigue affect use.
Read the ambulatory glucose profile in sequence
Confirm adequate active data, review time below range first, then time in range and time above range, variability, overnight patterns, meals, exercise, treatment timing, and repeated day-to-day features. The median line and percentile bands reveal typical exposure and variability. A single unusual day should not outweigh a reproducible pattern.
Pair devices with training and continued access
Technology selection should include the person and caregiver, and training should cover insertion, alarms, trend arrows, confirmatory testing, data sharing, troubleshooting, sick days, exercise, driving, and backup supplies. Interruption can be dangerous for insulin users. A technically advanced device that cannot be obtained, worn, understood, or trusted is not an effective plan.
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Lesson
Microvascular and Cardiovascular Surveillance
Complications are detected through a calendar and a risk map, not by waiting for symptoms. Kidney, eye, nerve, foot, cardiovascular, and heart-failure risk can progress silently.
- Kidney screening
- Retinal screening
- Neuropathy and feet
- ASCVD and heart failure
- Risk-factor integration
Pair urinary albumin with estimated filtration and repeat abnormal findings
Use timed retinal review and complete neurologic and vascular examination
Treat pressure, lipids, tobacco, kidney risk, heart failure, and activity
Screen kidney function through filtration and albumin
Assess urinary albumin-to-creatinine ratio and estimated GFR at least annually in type 2 diabetes and in type 1 diabetes beginning after five years, with more frequent monitoring when CKD is present. Repeat abnormal albumin because exercise, infection, fever, heart failure, marked hyperglycemia, menstruation, and blood pressure can transiently raise it. Active sediment, abrupt decline, nephrotic features, or atypical timing suggests another kidney disease.
Protect vision before symptoms appear
Adults with type 2 diabetes need an initial comprehensive dilated eye examination at diagnosis, while adults with type 1 diabetes begin within five years after onset. Interval depends on findings, glycemia, pregnancy, and progression. Rapid glycemic improvement can transiently worsen existing retinopathy, so high-risk patients need coordinated eye follow-up rather than avoidance of needed control.
Examine nerves, skin, structure, and blood flow
Assess peripheral neuropathy at type 2 diagnosis and after five years of type 1 diabetes, then at least annually. Combine history with small-fiber and large-fiber assessment. Use a 10 g monofilament to identify loss of protective sensation and at least one additional neurologic test. Inspect skin, deformity, pulses, footwear, prior ulcer, amputation, kidney disease, and self-care ability.
Treat cardiovascular and heart-failure risk as core diabetes care
Review ASCVD, heart failure, CKD, blood pressure, lipids, tobacco, weight, activity, sleep, social conditions, and family history. Routine coronary screening in an asymptomatic person is not a substitute for risk-factor treatment. Cardiorenal protective treatment can be indicated independent of current A1C, which is addressed in the pharmacotherapy module.
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Lesson
Hypoglycemia and Longitudinal Care
Safe diabetes care repeatedly reviews low glucose, self-management capacity, mental health, food and medication access, health literacy, and the life context in which every plan must work.
- Hypoglycemia levels
- Awareness and risk
- Glucagon preparedness
- DSMES
- Social and functional context
Separate alert glucose from clinically significant and assisted events
Match treatment to consciousness, swallowing safety, and recurrence risk
Education, access, cognition, distress, schedule, and trained responders
Classify hypoglycemia by glucose and function
Level 1 is glucose below 70 and at least 54 mg/dL. Level 2 is below 54 mg/dL and requires immediate action. Level 3 is any severe event with altered mental or physical function requiring another person's assistance, regardless of the measured glucose. Review timing, symptoms, awareness, activity, alcohol, intake, kidney function, medication, and recurrence.
Treat the person and prevent the next event
A conscious person usually treats with fast-acting glucose and rechecks after 15 minutes, with individualized carbohydrate amounts for automated insulin delivery and exercise contexts. An unresponsive or unsafe person needs glucagon and emergency support, not oral intake. Prescribe glucagon for people using insulin or at high risk and train family, peers, school, workplace, or caregivers.
Identify impaired awareness and fear
Recurrent hypoglycemia can blunt autonomic warning and increase severe-event risk. Screen awareness at least annually and after clinically important events. Avoidance of hypoglycemia, structured education, CGM, and treatment adjustment can improve awareness. Fear of hypoglycemia can also drive persistent hyperglycemia and needs direct, nonjudgmental assessment.
Make education and social conditions part of treatment
Diabetes self-management education and support should be available at diagnosis, during reassessment, when complications or transitions occur, and when goals are not met. Review medication and food access, housing, work or school schedule, language, numeracy, vision, hearing, dexterity, cognition, distress, depression, eating disorder risk, support, culture, and priorities. A plan that cannot be executed is not clinically complete.
Quick check
Module test
Check the connections.
Each attempt draws 10 questions from the complete 100 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Lecture material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.