Type1 Diabetes Mellitus: Case Discussion and Key Learning Points
Model Case Presentation
Patient Demographics
Name: Miss Riya, Age: 10 years, Gender: Female, Informant: Mother (Reliable)
Chief Complaints
- Increased urination and thirst – 2 months
- Loss of weight despite increased appetite – 2 months
- Vomiting, abdominal pain, and excessive lethargy – 2 days
History Summary
Previously healthy child, passing large volumes of urine frequently (including nocturia and new-onset nocturnal enuresis), drinking water excessively (~4–5 litres/day), and eating more than usual yet losing approximately 4 kg over 2 months. Over the past 2 days, she developed nausea, bilious vomiting (~4 episodes), diffuse abdominal pain, deep rapid breathing, and progressive drowsiness.
No history of similar episodes before. No family history of diabetes in first-degree relatives. No history of steroid use or recurrent infections. Born term, NVD, immunizations up to date. Non-consanguineous marriage.
Examination Summary
| Parameter | Finding | Significance |
|---|---|---|
| Weight | 26 kg (was 30 kg) | Loss of 4 kg — catabolism |
| RR | 36/min, deep | Kussmaul breathing (DKA) |
| HR | 124/min | Tachycardia — dehydration |
| BP | 90/60 mmHg | Borderline low — ~7% dehydration |
| GCS | 13/15 | Mild altered sensorium |
| Breath odour | Fruity / acetone | Ketonemia |
| Temperature | 37.2°C | Normal |
| Skin | Dry, reduced turgor, sunken eyes | ~7% dehydration |
| BMI | Low-normal | Thin build — consistent with T1DM |
Systemic Examination: Diffuse mild abdominal tenderness (no guarding/rigidity — pseudo-peritonitis of DKA). No hepatomegaly. No lymphadenopathy. No features of hypothyroidism or Cushing's.
Neurological: Drowsy but arousable; pupils equal and reactive. No focal deficits.
Bedside: Blood glucose (glucometer) = 425 mg/dL. Urine: 4+ glucose, 3+ ketones.
✅ Complete Diagnosis
Type 1 Diabetes Mellitus — New Onset, Presenting in Moderate Diabetic Ketoacidosis (DKA) with approximately 7% Dehydration.
💡 Staging of T1DM (ADA/JDRF)
Stage 1: ≥2 autoantibodies positive, normoglycemia, asymptomatic.
Stage 2: ≥2 autoantibodies + dysglycemia (impaired FPG or IGT), asymptomatic.
Stage 3: Clinical diagnosis — symptomatic hyperglycemia / DKA.
Most children present at Stage 3.
📝 History — Exam Q&A
T1DM is an autoimmune disease characterised by selective destruction of pancreatic beta cells, leading to absolute insulin deficiency. The patient is entirely dependent on exogenous insulin.
| Feature | Type 1 DM | Type 2 DM |
|---|---|---|
| Mechanism | Autoimmune beta-cell destruction | Insulin resistance + relative deficiency |
| Age | Usually <20 years (peak 5–7 yr, puberty) | Adults; increasing in obese adolescents |
| Body habitus | Thin / normal weight | Usually overweight / obese |
| Autoantibodies | Positive (GADA, IA-2A, ZnT8A, IAA) | Negative |
| C-peptide | Very low / undetectable | Normal or elevated |
| Ketosis | Prone to DKA | Rare (HHS more common) |
| Insulin requirement | Mandatory lifelong | Oral agents ± insulin |
| Symptom | Mechanism |
|---|---|
| Polyuria | Glucose exceeds renal threshold (~180 mg/dL) → osmotic diuresis → excess urine output |
| Polydipsia | Fluid loss from polyuria → dehydration → thirst |
| Polyphagia | No intracellular glucose uptake (no insulin) → cells starve → hunger signals despite hyperglycemia |
| Weight loss | Catabolism: fat lipolysis, protein breakdown (gluconeogenesis), glycogen depletion; glucose lost in urine |
| Nocturia / enuresis | Osmotic diuresis continues at night — secondary enuresis in a previously toilet-trained child is a RED FLAG |
| Fatigue / weakness | Energy deficit due to absent insulin-mediated glucose utilisation |
Several reasons:
- Delayed recognition — classic symptoms (polyuria, polydipsia) are missed or attributed to UTI, growth spurts, or behavioural issues
- Rapid beta-cell loss — especially in younger children; absolute insulin deficiency develops quickly
- No insulin → lipolysis → FFA → ketogenesis → ketonemia → metabolic acidosis
- Intercurrent illness (e.g., viral URTI) may precipitate DKA by increasing counter-regulatory hormones (glucagon, catecholamines, cortisol, GH)
DKA at first presentation is most common in: <5 years of age, no family history of T1DM, lower socioeconomic status, delayed medical access.
After insulin therapy is started, residual beta cells temporarily recover function → endogenous insulin secretion partially resumes. This causes:
- Reduced exogenous insulin requirement (often <0.5 U/kg/day)
- Near-normal blood glucose control with low insulin doses
- Elevated C-peptide (detectable)
Duration: Weeks to months (rarely up to 1–2 years)
Clinical relevance: Reduce insulin doses to avoid hypoglycemia; inform parents the disease has NOT resolved — permanent beta-cell loss will follow.
⚠️ Key Point
NEVER stop insulin during the honeymoon phase — residual beta-cell function is temporary and insulin must be continued to preserve remaining cells.
- No steroid use — rules out steroid-induced diabetes
- No recurrent pancreatitis — rules out pancreatogenic DM
- No cystic fibrosis — CF-related diabetes
- No syndromic features — Wolfram syndrome (DM + DI + optic atrophy + deafness), Down syndrome, Turner syndrome (associated with T1DM)
- No obesity / acanthosis nigricans — helps differentiate from T2DM or MODY
- Family history of autoimmune conditions — thyroid disease, vitiligo, Addison's (associated with T1DM)
- Dietary history — celiac disease (associated; wheat-free diet may be needed)
| Type | Key Feature |
|---|---|
| Type 1A (Autoimmune) | Most common in children; autoantibodies positive; HLA-DR3/DR4 association |
| Type 1B (Idiopathic) | Autoantibody negative; more in Asian/African populations |
| Type 2 DM | Insulin resistance; obese adolescents; rising incidence; acanthosis nigricans |
| MODY (Maturity Onset Diabetes of the Young) | Single-gene mutation; autosomal dominant; usually non-ketotic; responds to specific therapy (e.g., MODY2 – no treatment, MODY3 – sulfonylurea) |
| Neonatal DM | Onset <6 months; may be transient or permanent; KATP channel mutations (sulfonylurea responsive) |
| Secondary DM | CF-related DM, steroid-induced, pancreatogenic, haemochromatosis |
HLA associations (chromosome 6p21):
- Risk alleles: HLA-DR3/DQ2 and HLA-DR4/DQ8 — present in >90% of T1DM patients
- Highest risk: HLA-DR3/DR4 heterozygote
- Protective allele: HLA-DQ6 (DQB1*0602) — strongly protective
Familial risk:
- General population: ~0.4%
- Mother with T1DM: ~2–3%
- Father with T1DM: ~5–6%
- Both parents: ~25–30%
- HLA-identical sibling: ~16%
- Monozygotic twin: ~30–50% (not 100% — environmental triggers needed)
Environmental triggers: Viral infections (Coxsackievirus B4, enteroviruses), early cow's milk exposure, vitamin D deficiency (hypotheses — not fully proven).
MODY = Maturity Onset Diabetes of the Young — a group of monogenic diabetes caused by single-gene mutations affecting beta-cell function.
| Feature | T1DM | MODY |
|---|---|---|
| Inheritance | Polygenic / multifactorial | Autosomal dominant |
| Autoantibodies | Positive | Negative |
| Ketosis | Prone to DKA | Rare |
| Family history | Variable | 3 generations affected (AD pattern) |
| C-peptide | Very low | Detectable / normal |
| BMI | Thin | Normal |
| Treatment | Insulin mandatory | Type-specific (diet / SU / insulin) |
Common MODY subtypes: MODY2 (GCK — mild stable hyperglycemia, often no treatment needed), MODY3 (HNF-1α — sulfonylurea responsive), MODY5 (HNF-1β — renal anomalies).
Diagnosis: Genetic testing (next-generation sequencing).
🩺 Examination — Exam Q&A
- Kussmaul breathing — deep, rapid, sighing respiration (respiratory compensation for metabolic acidosis)
- Fruity / acetone breath — exhaled acetone from ketonemia
- Dehydration — dry mucous membranes, sunken eyes, reduced skin turgor, reduced capillary refill
- Tachycardia — from dehydration and acidosis
- Hypotension — in severe dehydration / shock
- Abdominal tenderness — "pseudo-peritonitis" of DKA (no guarding or rigidity; resolves with treatment)
- Altered consciousness / GCS reduction — cerebral dysfunction from acidosis or cerebral edema
⚠️ Important
Abdominal pain and vomiting in DKA can mimic a surgical abdomen. NEVER operate until DKA is corrected and reassessed.
Clinical signs of dehydration in DKA are often underestimated because hyperosmolality from hyperglycemia maintains intravascular volume longer than isotonic dehydration. Dehydration in DKA is usually classified clinically:
| Degree | Clinical Signs |
|---|---|
| Mild (~5%) | Slightly dry mucous membranes; alert; normal pulse and BP |
| Moderate (~7%) | Dry skin, reduced turgor, sunken eyes, tachycardia, reduced urine output, BP borderline |
| Severe (>10%) | Above + hypotension, poor perfusion, prolonged CRT, obtunded — impending shock |
Note: ISPAD 2022 guidelines recommend assuming 5–10% dehydration for calculation purposes in DKA, regardless of clinical appearance.
| Severity | Venous pH | Bicarbonate | Consciousness |
|---|---|---|---|
| Mild | 7.20 – 7.30 | 10 – 15 mEq/L | Alert |
| Moderate | 7.10 – 7.20 | 5 – 10 mEq/L | Alert or drowsy |
| Severe | <7.10 | <5 mEq/L | Stupor / coma |
All require: Blood glucose >200 mg/dL + ketonemia/ketonuria + acidosis.
- Thin / wasted build — weight loss, muscle wasting (catabolism)
- Short stature — in poorly controlled, long-standing T1DM (Mauriac syndrome)
- Injection site changes — lipohypertrophy (nodular thickening at sites of repeated injection), lipoatrophy
- Vitiligo — associated autoimmune skin condition
- Signs of hypothyroidism — goitre, dry skin, bradycardia (associated Hashimoto's thyroiditis)
- Abdominal distension / failure to thrive — if associated celiac disease
- No acanthosis nigricans — helps differentiate from T2DM / insulin resistance states
Mauriac Syndrome is seen in long-standing, poorly controlled T1DM in children. Features:
- Growth retardation / short stature
- Delayed puberty
- Hepatomegaly — due to glycogen accumulation in liver (glycogenic hepatopathy)
- Moon face (pseudo-Cushing's from high insulin levels)
- Protuberant abdomen
Seen in era of poor glycemic control; now rare with modern management.
| System | Examination | Complication |
|---|---|---|
| Eyes | Fundoscopy — neovascularization, exudates, haemorrhages | Diabetic retinopathy |
| Kidneys | BP, peripheral oedema | Diabetic nephropathy |
| Feet | Peripheral pulses, sensation (monofilament), reflexes, ulcers | Diabetic neuropathy, foot disease |
| Skin | Injection sites — lipohypertrophy / lipoatrophy | Poor absorption from hypertrophic sites |
| Growth | Height, weight, pubertal staging (Tanner) | Growth failure in poor control |
| Thyroid | Neck for goitre | Autoimmune thyroiditis (Hashimoto's) |
Cerebral edema is the most feared complication of DKA, occurring in 0.3–1% of pediatric DKA and carrying ~20–25% mortality.
Warning signs (during treatment):
- Headache (new, worsening)
- Sudden behavioral change / agitation / irritability
- Deteriorating GCS despite improving biochemistry
- Bradycardia + hypertension (Cushing's triad)
- Papilledema (late)
- Cranial nerve palsies (CN III, VI)
- Respiratory irregularity
Risk factors: Young age, new-onset T1DM, severe acidosis (low bicarbonate), high initial BUN, excessive hypotonic fluids, rapid fall in blood glucose, use of bicarbonate.
🔬 Investigations — Exam Q&A
Any ONE of the following (ADA / WHO criteria):
- Fasting plasma glucose ≥ 126 mg/dL (fasting = no caloric intake for ≥8 hours)
- Random plasma glucose ≥ 200 mg/dL + classic symptoms (polyuria, polydipsia, weight loss)
- 2-hour plasma glucose ≥ 200 mg/dL during OGTT (75 g glucose)
- HbA1c ≥ 6.5%
💡 Note
In symptomatic patients, a single abnormal test is diagnostic. In asymptomatic patients, TWO abnormal results on separate occasions are required to confirm diagnosis.
Bedside / Immediate:
- Blood glucose (glucometer)
- Urine: glucose + ketones (dipstick)
- Blood ketones (beta-hydroxybutyrate) — if available
Lab investigations:
- Blood gas (venous/arterial) — pH, bicarbonate, pCO₂ (assess acidosis, respiratory compensation)
- Serum electrolytes — Na⁺, K⁺, Cl⁻ (critical before insulin)
- Blood glucose (lab)
- Blood urea, creatinine — renal function
- CBC — leukocytosis (stress response, not always infection)
- Calcium, Magnesium, Phosphate — fall during treatment
- HbA1c — confirms chronic hyperglycemia
- Urine culture — if infection suspected
- CRP / cultures — if precipitating infection suspected
Hyperglycemia draws water from the intracellular to extracellular space, diluting serum sodium (pseudohyponatremia).
Corrected Na⁺ = Measured Na⁺ + 1.6 × [(Blood glucose – 100) / 100]
Example: Measured Na = 128 mEq/L, Blood glucose = 500 mg/dL → Corrected Na = 128 + 1.6 × 4 = 134.4 mEq/L (normal)
Importance: If corrected Na is falling during treatment (should rise as glucose falls), it suggests excessive hypotonic fluid administration → risk of cerebral edema.
| Antibody | Full Name | Notes |
|---|---|---|
| GADA | Glutamic Acid Decarboxylase Antibodies | Most common (~80%); persists longest; also in LADA |
| IA-2A | Islet Antigen-2 Antibodies | High specificity; predicts rapid progression |
| IAA | Insulin Autoantibodies | Most common in young children (<5 yr); disappears after insulin therapy starts |
| ZnT8A | Zinc Transporter 8 Antibodies | Useful when others negative; relatively specific |
| ICA | Islet Cell Antibodies | Older marker; less used now; detected by immunofluorescence |
Presence of ≥2 antibodies confers very high risk of progression to clinical T1DM (Stage 1 → 3 inevitable).
HbA1c reflects the average blood glucose over the past 2–3 months (life of an RBC). It is formed by non-enzymatic glycation of haemoglobin.
Target in children with T1DM: <7% (ADA 2024 / ISPAD 2022) — applicable to all pediatric age groups (individualised approach).
Limitations / Falsely LOW HbA1c:
- Haemolytic anaemia, iron deficiency anaemia (increased RBC turnover)
- Haemoglobin variants (HbS, HbC) — alter glycation or assay
- Recent blood transfusion
- Pregnancy
Falsely HIGH HbA1c:
- Iron deficiency anaemia (reduced RBC turnover)
- Asplenia
When HbA1c is unreliable: Use Fructosamine (reflects 2–3 week glucose average) or time-in-range (TIR) from CGM data.
C-peptide is a by-product of proinsulin cleavage produced in equimolar amounts with insulin by beta cells. It reflects endogenous insulin secretion (exogenous insulin contains no C-peptide).
| Condition | C-peptide |
|---|---|
| T1DM (established) | Very low / undetectable |
| T2DM | Normal or elevated |
| MODY | Detectable / normal |
| Honeymoon phase (T1DM) | Detectable (residual beta-cell function) |
| Insulinoma | Very high |
| Exogenous insulin overdose | Suppressed (low) |
Uses: Differentiating T1DM from T2DM/MODY, assessing residual beta-cell function, distinguishing factitious hypoglycemia from insulinoma.
| Investigation | When to Start Screening | Purpose |
|---|---|---|
| Urine microalbumin:creatinine ratio | After 5 years of T1DM or at puberty (whichever earlier) | Early nephropathy |
| Fundoscopy / retinal exam | After 5 years of T1DM or at puberty | Retinopathy |
| Fasting lipid profile | At diagnosis (if >2 yr), repeat every 1–5 yr | Dyslipidemia |
| Thyroid function tests + anti-TPO | At diagnosis; annually | Autoimmune thyroiditis (Hashimoto's) |
| Celiac antibodies (tTG-IgA + total IgA) | At diagnosis; every 2–5 yr | Celiac disease (~5–10% of T1DM) |
| Blood pressure | Every visit | Hypertension risk |
| HbA1c | Every 3 months | Glycemic control monitoring |
💊 Management — Exam Q&A
Step 1 — Resuscitation (If shocked):
IV 0.9% Normal Saline 10 mL/kg bolus over 30–60 minutes. Repeat once if needed. (Avoid large volume boluses — cerebral edema risk).
Step 2 — Fluid replacement (Rehydration):
Calculate total fluid = Maintenance (24 hr) + Deficit (% dehydration × weight in mL)
Replace over 48 hours using isotonic saline (0.9% NS) initially. Switch to 0.45% NS + dextrose when BG <250–300 mg/dL.
Subtract any bolus given from total fluid.
Step 3 — Insulin infusion:
- Start only after initial fluid bolus AND confirm K⁺ ≥ 3.5 mEq/L
- Rate: 0.05–0.1 U/kg/hour Regular insulin IV infusion (ISPAD 2022 recommends 0.05 U/kg/hr to reduce cerebral edema risk)
- Continue until DKA is resolved (pH >7.30, HCO₃ >15, anion gap normal, able to eat)
Step 4 — Potassium replacement:
- K⁺ depleted in ALL DKA (total body deficit despite normal/high serum K⁺ initially)
- Add K⁺ 40 mEq/L to IV fluid when K⁺ <5.5 mEq/L and urine output confirmed
- If K⁺ <3.5 — hold insulin, give K⁺ first
Step 5 — Monitoring:
Hourly: BG, vital signs, neuro status; Every 2 hourly: electrolytes, venous gas.
Corrected Na⁺ should rise as glucose falls — falling corrected Na⁺ is a red flag for cerebral edema.
🚨 Avoid
- Bicarbonate — not recommended; increases cerebral edema risk, worsens paradoxical CNS acidosis
- Excessive/rapid fluids — major risk factor for cerebral edema
- Insulin bolus at initiation — not recommended in children
In DKA, the serum K⁺ is falsely normal or elevated due to acidosis-driven shift of K⁺ from intracellular to extracellular space (H⁺ enters cell, K⁺ exits). Total body K⁺ is depleted.
When insulin is given:
- Acidosis corrects → K⁺ shifts back into cells
- Insulin itself drives K⁺ into cells (activates Na⁺/K⁺-ATPase)
- Diuresis further depletes K⁺
Result: Rapid, severe hypokalemia → life-threatening cardiac arrhythmias (ventricular fibrillation).
Rule: If K⁺ <3.5 mEq/L — hold insulin, replace K⁺ first.
Act immediately — do not wait for CT scan to start treatment:
- Mannitol 0.5–1 g/kg IV over 15–20 minutes — osmotic agent; may repeat in 30 min if no response
- Alternatively: 3% Hypertonic Saline 2.5–5 mL/kg IV over 15–30 minutes (preferred if hyponatremic)
- Reduce IV fluid rate to ⅓ of calculated rate
- Elevate head of bed 30°
- Restrict IV fluid to minimum
- Consider intubation if GCS deteriorating / apneic
- Arrange CT brain once stabilized
| Type | Examples | Onset | Peak | Duration |
|---|---|---|---|---|
| Ultra-rapid | Faster Aspart, Inhaled insulin | ~5 min | 30–90 min | 3–4 hr |
| Rapid-acting | Lispro, Aspart, Glulisine | 15 min | 1–2 hr | 3–5 hr |
| Short-acting | Regular (Soluble) | 30–60 min | 2–4 hr | 6–8 hr |
| Intermediate | NPH (Isophane) | 2–4 hr | 6–10 hr | 12–18 hr |
| Long-acting | Glargine, Detemir | 2–4 hr | Flat / no peak | 20–24 hr |
| Ultra-long-acting | Degludec | 1–2 hr | No peak | >42 hr |
Note: Glargine must NOT be mixed with other insulins (changes pH). Detemir may be given twice daily in children. Regular insulin is the only one given IV.
1. Basal-Bolus Regimen (Multiple Daily Injections — MDI) — Gold standard / preferred
- Basal: Glargine or Detemir once (or twice) daily — 40–50% of Total Daily Dose (TDD)
- Bolus: Rapid-acting insulin before each meal — 50–60% of TDD split equally across 3 meals
- + Correction dose for hyperglycemia (using insulin sensitivity factor)
- Allows flexible dosing based on carbohydrate intake
2. Conventional (Fixed) Regimen — 2 injections/day
- Morning: NPH + Regular (or rapid-acting) — 2/3 of TDD
- Evening: NPH + Regular — 1/3 of TDD
- Less flexible; risk of nocturnal hypoglycemia from NPH peak
3. CSII — Continuous Subcutaneous Insulin Infusion (Insulin Pump)
- Delivers programmable basal rate + bolus at meal/correction
- Uses only rapid-acting insulin (e.g., lispro/aspart)
- Preferred for: young children, frequent hypoglycemia, dawn phenomenon, poor compliance with MDI
Total Daily Dose (TDD):
- New onset / Honeymoon phase: 0.5 U/kg/day
- Pre-pubertal children (established): 0.7–1.0 U/kg/day
- During puberty: 1.0–1.5 U/kg/day (due to insulin resistance from GH/sex steroids)
Insulin Sensitivity Factor (Correction Factor):
= 1800 ÷ TDD (for rapid-acting insulin)
= 1500 ÷ TDD (for regular insulin)
This tells you how much 1 unit of insulin lowers blood glucose (in mg/dL).
Insulin-to-Carbohydrate Ratio (ICR):
= 500 ÷ TDD
This tells you how many grams of carbohydrate 1 unit covers.
Definition (ISPAD 2022):
- Level 1 (Alert): BG <70 mg/dL (<3.9 mmol/L)
- Level 2 (Clinically significant): BG <54 mg/dL (<3.0 mmol/L)
- Level 3 (Severe): Any BG causing altered consciousness/seizure requiring external assistance
Symptoms: Shakiness, sweating, pallor, palpitations (adrenergic); confusion, headache, seizure (neuroglycopenic).
Management — "Rule of 15":
- Conscious child: 15 g fast-acting carbohydrate (3 glucose tablets, 150 mL juice) orally → recheck BG after 15 minutes → repeat if still <70 mg/dL → eat a snack
- Unconscious / unable to swallow:
- Glucagon IM/SC: <25 kg → 0.5 mg; >25 kg → 1 mg
- Dextrose IV: 10% dextrose 2 mL/kg (or 25% dextrose 1 mL/kg) IV slowly
- Nasal glucagon: Baqsimi (3 mg intranasal) — available in some countries
| Feature | Dawn Phenomenon | Somogyi Effect |
|---|---|---|
| Mechanism | Early morning surge of GH and cortisol (3–8 AM) → insulin resistance → hyperglycemia | Rebound hyperglycemia after nocturnal hypoglycemia (counter-regulatory response) |
| 3 AM BG | Normal or mildly elevated | Low (<70 mg/dL) |
| Morning BG | High | High |
| Management | Increase evening basal insulin dose or switch to insulin pump with variable basal rate | Reduce evening insulin dose; add bedtime snack |
💡 Note
The Somogyi effect is controversial — multiple studies have failed to consistently demonstrate nocturnal hypoglycemia preceding morning hyperglycemia. The Dawn Phenomenon is well-established and clinically important.
- NEVER stop insulin — even if the child is not eating (infections increase counter-regulatory hormones → more insulin is often needed)
- Check BG every 2–4 hours
- Check urine/blood ketones — if BG >240 mg/dL
- Increase fluid intake — sugar-free fluids if BG high; juice/cola if BG low
- Give correction doses of rapid-acting insulin for high BG + ketonemia
- When to seek emergency: Persistent vomiting (unable to keep fluids down), BG persistently >300 mg/dL, moderate-large ketones, altered sensorium
- Balanced, nutritious diet — same as recommended for all children (no "diabetic diet"); emphasis on whole grains, vegetables, lean protein
- Carbohydrate counting — cornerstone of modern T1DM management with MDI; counts grams of carbohydrate per meal to calculate mealtime insulin dose
- Consistent meal timing — especially important with conventional regimens
- Avoid simple sugars / refined carbohydrates (fast-absorbing → rapid glucose spikes)
- High-glycaemic index foods should be limited
- Fiber intake — slows glucose absorption
- Caloric intake — normal for age; avoid caloric restriction (risk of disordered eating in adolescents)
- Gluten-free diet if associated celiac disease confirmed
Microvascular:
- Retinopathy — rare before 5 years of disease; screen from 5 years duration or puberty. Background (non-proliferative) → Proliferative → Blindness
- Nephropathy — earliest sign is microalbuminuria (>30 mg/g creatinine); treat with ACE inhibitor. Rare before 5 years of disease
- Neuropathy — peripheral sensorimotor; autonomic (gastroparesis, postural hypotension, anhidrosis); less common in children
Macrovascular (rare in children, established in adulthood):
- Premature atherosclerosis → Cardiovascular disease, stroke
Other:
- Limited joint mobility (cheiroarthropathy) — painless stiff hands due to glycation of collagen; "prayer sign" positive
- Lipohypertrophy / lipoatrophy — at injection sites
- Growth failure — Mauriac syndrome in poorly controlled
Best prevention: Optimal glycemic control (HbA1c <7%) + BP control + regular screening.
🔭 Recent Advances — Exam Q&A
CGM measures interstitial glucose every 1–5 minutes via a sensor placed subcutaneously, displaying real-time glucose trends and alerts.
Examples: Dexcom G6/G7, FreeStyle Libre 2/3, Medtronic Guardian.
Advantages over fingerprick SMBG:
- Continuous data — detects nocturnal hypoglycemia
- Trend arrows — can predict glucose direction
- Alerts for hypoglycemia and hyperglycemia
- Reduces need for fingerprick testing
Time-in-Range (TIR) — Targets (ISPAD 2022):
- Target range: 70–180 mg/dL
- TIR goal: >70% of time in target range
- Time below range (<70): <4% (<1 hr/day)
- Time above range (>180): <25%
TIR correlates with HbA1c and microvascular complications and is now considered a complementary metric to HbA1c.
A Closed-Loop System (CLS) or Automated Insulin Delivery (AID) integrates:
- CGM — real-time glucose sensor
- Algorithm — software that calculates insulin dose based on glucose trends
- Insulin pump (CSII) — automatically adjusts basal insulin delivery
The user still announces meals (meal bolus), but the system handles basal insulin automatically ("hybrid" closed loop). Fully closed-loop systems are under research.
FDA-approved / available systems: MiniMed 780G, Omnipod 5, Tandem Control-IQ, iAPS (open-source).
Benefits in children: Improved TIR, reduced HbA1c, decreased hypoglycemia (especially nocturnal), reduced caregiver burden.
Teplizumab (Tzield) is an anti-CD3 monoclonal antibody that modulates autoreactive T lymphocytes (the cells destroying beta cells) without global immunosuppression.
FDA approved November 2022 — the first disease-modifying agent approved for T1DM.
Indication: Patients aged ≥8 years with Stage 2 T1DM (≥2 positive autoantibodies + dysglycemia, but no clinical symptoms).
Administration: 14-day course of IV infusion (once daily).
Efficacy: Clinical trials showed it delayed progression from Stage 2 to clinical T1DM (Stage 3) by a median of ~2–3 years.
Limitations: Does not cure T1DM; only delays progression; significant cost; side effects include cytokine release syndrome, lymphopenia, rash.
Smart insulin pens (e.g., InPen, Tempo Pen) are insulin delivery devices that:
- Record the dose, timing, and type of insulin given
- Connect to a smartphone app via Bluetooth
- Integrate with CGM data
- Provide dose reminders and bolus calculations
- Store data for clinician review
Advantage: Bridge technology for patients on MDI who cannot afford or access a pump — improves dose tracking, reduces missed doses, aids dose calculations.
- Islet transplantation — from cadaveric donors into portal vein; limited by donor supply and lifelong immunosuppression; currently for adult T1DM with severe hypoglycemia unawareness
- Stem cell-derived beta cells — VX-880 (Vertex Pharmaceuticals): embryonic stem cell-derived islets; early human trials showing insulin independence; requires immunosuppression
- Encapsulated islet devices — engineered "immune-protected" islets (e.g., ViaCyte's PEC-Encap) — no immunosuppression needed; early-phase trials
- Other immunotherapies in trials: Abatacept (CTLA-4-Ig), Anti-IL-21 + liraglutide, rituximab (anti-CD20) — targeting different arms of autoimmunity
- Antigen-specific immunotherapy — insulin peptide vaccination to re-educate autoreactive T cells; under research
⚡ Key Points — Quick Revision
🧮 DKA Fluid & Insulin Quick Calculator
One-Liners for Exam
- T1DM: Autoimmune absolute insulin deficiency
- Classic triad + 1: Polyuria, polydipsia, polyphagia + weight loss
- NEW secondary enuresis in a school-age child = RED FLAG for T1DM
- DKA triad: Hyperglycemia (>200) + Ketonemia/uria + Acidosis (pH <7.3 / HCO₃ <15)
- Kussmaul breathing = deep, sighing respirations = respiratory compensation for metabolic acidosis
- Fruity breath = ketonemia (exhaled acetone)
- DKA fluid: 0.9% NS bolus (10 mL/kg) → Rehydrate over 48 hours → Switch to 0.45%NS+Dextrose when BG <250
- Insulin in DKA: 0.05–0.1 U/kg/hr IV Regular insulin; START only after fluid bolus AND K⁺ ≥ 3.5
- K⁺ in DKA: Serum normal/high (acidosis) but TOTAL BODY depleted; falls rapidly with insulin → always replace
- Avoid in DKA: Bicarbonate, rapid/hypotonic fluids, insulin bolus
- Most feared DKA complication: Cerebral edema → Tx: Mannitol 0.5–1 g/kg OR 3% HTS 2.5–5 mL/kg
- Corrected Na⁺ falling during DKA treatment = warning sign for cerebral edema
- Gold standard investigation: Plasma glucose + HbA1c
- Best autoantibody: GADA (most common); IAA (highest in young children)
- C-peptide: Low in T1DM, detectable in MODY/T2DM, suppressed in exogenous insulin overdose
- HbA1c target: <7% (all pediatric age groups — ISPAD/ADA 2022–2024)
- Honeymoon phase: Residual beta-cell function post-diagnosis; NEVER stop insulin
- Best insulin regimen: Basal-bolus MDI (gold standard) or CSII (pump)
- Puberty insulin requirement: Up to 1.5 U/kg/day (GH-mediated insulin resistance)
- Dawn phenomenon: Morning hyperglycemia from GH/cortisol surge (3 AM BG normal)
- MODY vs T1DM: MODY = autosomal dominant, antibody negative, C-peptide detectable, non-ketotic
- Annual screening: TFT + anti-TPO, celiac antibodies (tTG-IgA), microalbuminuria, fundoscopy, lipid profile
- Mauriac syndrome: Poor control → short stature + hepatomegaly + delayed puberty
- Teplizumab (Tzield): Anti-CD3; FDA approved 2022; delays Stage 2→3 T1DM by ~3 years
- Closed-loop system: CGM + algorithm + pump = artificial pancreas (e.g., MiniMed 780G)
- TIR target: >70% time in 70–180 mg/dL range
💡 High-Yield Associations with T1DM
- Hashimoto's thyroiditis (most common associated autoimmune condition in T1DM)
- Celiac disease (~5–10% of T1DM)
- Addison's disease (autoimmune adrenalitis)
- Vitiligo
- Pernicious anaemia
- All above + T1DM = Autoimmune Polyglandular Syndrome (APS) Type II / Type III