Diabetes Management

Diagnosing Type 2 Diabetes (T2DM)

  • Fasting Blood Glucose (FBG): Fasting (8 hours). May detect Impaired Fasting Glucose (IFG).
  • HbA1c: Non-fasting. Threshold of 6.5% (48 mmol/mol) linked to microvascular disease and better predictor of macrovascular disease than FBG or 2-hour post-glucose.
  • Oral Glucose Tolerance Test (OGTT): 8-hour fast, then 75 g glucose orally with samples fasting and at 2 hours. Only method able to detect Impaired Glucose Tolerance (IGT).
  • Asymptomatic Individuals: Repeat and confirm abnormal values on a different day. If negative, reassess in 1 year or earlier if symptomatic.
  • Symptomatic/Acute: Repeat testing not required if unequivocal hyperglycemia with acute metabolic decompensation or obvious symptoms.
  • HbA1c Limitations: Less accurate in acute-onset glycemic states (post-traumatic T2DM, sepsis, steroid use), within 4 months postpartum, hemoglobinopathy, hemolysis, advanced CKD, iron deficiency (falsely elevated), or recent transfusion. Not useful for IGT.
  • Venous Sampling: Required for diagnosis; capillary finger-prick glucose is not acceptable in asymptomatic patients.
  • Discordant Results: Repeat the test showing a value above the diagnostic threshold to confirm diagnosis.
Procedure Requirement Notes
Fasting Eight hours Only method to detect IGT
Glucose Load 75 g glucose administered orally May concurrently detect IFG
Sample Collection Fasting venous sample + 2-hour post-glucose venous sample —
Confirmation Repeat abnormal values in asymptomatic people, confirm on a different day —

Assessing Diabetes Risk

  • High-Risk Categories (regardless of AUSDRISK score):
    • AUSDRISK score ≥ 12
    • Any age with IGT or IFG
    • Overweight/obesity with age ≥ 40, or age 18-40 with hypertension or insulin resistance signs (acanthosis nigricans, dyslipidemia)
    • First-degree family history of T2DM
    • History of a cardiovascular event (MI, angina, PAD, stroke)
    • Certain ethnicities: Aboriginal and Torres Strait Islander, South Asian, South-east Asian, North African, Latin American, Middle Eastern, Māori, or Pacific Islander
    • History of GDM
    • PCOS
    • Antipsychotic medication (e.g. olanzapine) or long-term prednisolone
    • Dyslipidemia, independent of treatment
  • Testing Frequency for High-Risk Individuals:
    • Most high-risk individuals: every 3 years with FBG or non-fasting HbA1c.
    • Those with IGT or IFG: annually.

Diabetes Cycle of Care (Routine Monitoring)

  • At Least Six-Monthly: Weight, height, waist circumference, BMI. Blood pressure. HbA1c (Medicare funds up to 4/year). Foot assessment for complications.
  • At Least Annually: Review diet, physical activity, smoking, medications. Sick-day management and glucose monitoring review. Complication prevention discussion (eyes, feet, kidneys, CVD). Total cholesterol, triglycerides, HDL. Urinary microalbuminuria assessment.
  • At Least Every Two Years: Comprehensive eye examination (more frequent if high risk).
  • Additional Considerations: Psychosocial issues, diabetes distress, depression. Vaccination review — recommended: influenza, pneumococcus, dTpa, COVID-19, RSV (age >60); consider: Hepatitis B, Herpes Zoster.

Diabetic Complications: Chronic Kidney Disease (CKD)

  • Kidney Health Check: Offer to high-risk individuals — diabetes, hypertension, established CVD, family history of kidney failure, obesity (BMI ≥ 30), history of AKI, First Nations Australians ≥ 18 years, all Australians ≥ 60 years.
  • Screening Tests: Urine albumin-to-creatinine ratio (uACR) and eGFR.
  • uACR: Ideally early morning sample. Single abnormal result (≥ 3 mg/mmol) requires repeat within 3 months. Transient albuminuria can result from UTI, fever, menstruation, exercise, heart failure.
  • eGFR: Venous creatinine sample. If < 60 mL/min/1.73m², repeat within 7 days; if persistently low, repeat at 3 months.
  • CKD Diagnosis: At least two uACR results ≥ 3 mg/mmol OR two eGFR results < 60 mL/min/1.73m², confirmed over 3 months.
  • Screening Frequency: All T2D annually; T1D from 5 years post-diagnosis; Aboriginal and Torres Strait Islander peoples annually from diagnosis.
  • CKD Staging: GFR stages G1 (≥90) to G5 (<15/dialysis), combined with albuminuria categories A1 (<3.0), A2 (3.0-30), A3 (>30 mg/mmol).
  • Management Goals: Slow progression, reduce albuminuria by at least 30%, lower cardiovascular risk, avoid nephrotoxic medications, encourage lifestyle changes.
  • ACE Inhibitors/ARBs: First-line for hypertension with albuminuria; titrate to highest tolerated dose. Do not combine ACEi and ARB, or combine with direct renin inhibitors.
  • SGLT2 Inhibitors: (dapagliflozin, empagliflozin) Recommended if eGFR ≥ 20 mL/min/1.73m² to reduce CKD progression and CV events, regardless of albuminuria. Preferred over GLP-1RA for CKD.
  • GLP-1 Receptor Agonists: (dulaglutide, liraglutide, semaglutide) Alternative if SGLT2i contraindicated/not tolerated; can slow progression and reduce albuminuria.
  • Finerenone: Add if albuminuria persists despite maximal ACEi/ARB. Indicated if eGFR ≥ 25 mL/min/1.73m² and K⁺ ≤ 5.0 mmol/L.
  • Statins: Initiate regardless of absolute CVD risk; add ezetimibe/PCSK9 inhibitor if LDL targets unmet.
  • BP Targets: National Heart Foundation < 140/90 mmHg; Kidney Health Australia < 130/80 mmHg — individualize.
Prescribing Red Flag: Avoid the “triple whammy” — ACEi/ARB + diuretic + NSAID together.

Diabetic Complications: Cardiovascular Disease (CVD)

  • Risk Assessment: Use the Australian absolute CVD Risk Calculator. All people 45-79 years; people with diabetes 35-79 years.
  • Aboriginal and Torres Strait Islander people: Assess individual risk factors 18-29 years; formal assessment 30-79 years; consider reclassifying to higher risk category.
  • Māori, Pacific Islander, South Asian people: Consider reclassifying estimated risk higher if near a threshold.
  • Coronary Artery Calcium (CAC) Score: Can refine risk. CAC > 100 may upgrade risk; CAC of zero may allow downgrading.
  • Reassessment Intervals:
    • Low risk (<5%): every 2 years.
    • Moderate risk (5-10%): every 6-12 months.
    • High risk (>10%) or pre-existing CVD: as clinically indicated.
  • Statins: Maximum tolerated dose for all adults with T2DM and known prior CVD, irrespective of lipid levels (e.g. atorvastatin 40-80 mg, rosuvastatin 20-40 mg daily). First-line for dyslipidemia in diabetes.
  • Fibrates: (fenofibrate) Consider alongside statins (or alone if statin-intolerant) when fasting triglycerides ≥ 2.3 mmol/L or HDL < 1.0 mmol/L, particularly for DR progression.
  • Ezetimibe/PCSK9 inhibitors: Add if LDL < 1.4 mmol/L target unmet on maximal statin therapy.
  • Icosapent Ethyl: Consider for ASCVD/CVD risk on statin with controlled LDL but elevated triglycerides (1.5-5.6 mmol/L).
  • Aspirin (75-162 mg/day): Secondary prevention in diabetes with ASCVD history; not for primary prevention.
  • Clopidogrel (75 mg/day): For ASCVD with documented aspirin allergy.
  • SGLT2i/GLP-1RA: Prioritize for established/high-risk ASCVD to reduce MACE and mortality. Use SGLT2i for heart failure. SGLT2i preferred for CKD; GLP-1RA is the alternative.

Diabetic Complications: Neuropathy

  • Painful Neuropathy: Up to 50% of patients with distal symmetrical polyneuropathy experience pain. Exclude other causes (e.g. B12 deficiency, myeloma).
  • Autonomic Neuropathy: Difficulty recognizing hypoglycemia, orthostatic hypotension (>20 mmHg drop), silent ischemia/MI, sudden cardiorespiratory arrest, gastroparesis, diarrhea/constipation, reduced anal sphincter control, delayed bladder emptying, urinary incontinence, erectile dysfunction/retrograde ejaculation.
  • Screening: Annually from T2DM diagnosis. Small fiber: pinprick, temperature. Large fiber: 128-Hz tuning fork, 10-g monofilament, ankle reflexes. Inability to feel monofilament indicates loss of protective sensation.
  • Complications of Polyneuropathy: Foot ulcers, claw-toe deformity, Charcot arthropathy.
  • Drug Treatment for Painful Neuropathy:
    • First-line: Amitriptyline 25-150 mg at night.
    • Second-line: Duloxetine 60 mg daily (max 60 mg BID), Gabapentin 300 mg daily (max 1200 mg TID), Pregabalin 75 mg BID (max 300 mg BID).
    • Non-responsive cases: opioid analgesics (tramadol, tapentadol ER, oxycodone ER).
  • Management: Intensified glycemic control, optimized BP and lipids to prevent onset and slow progression.
  • Differential Diagnoses for Burning Foot Pain: Sciatica, tarsal tunnel syndrome, hypothyroidism-induced neuropathy, peripheral arterial disease, lumbar radiculopathy, vitamin B12 deficiency, uremic neuropathy, alcoholic neuropathy, multiple myeloma.

Diabetic Complications: Retinopathy (DR)

  • Screening: T2DM at diagnosis; T1DM within 5 years of diagnosis; Aboriginal and Torres Strait Islander peoples annually.
  • Pregnancy with Diabetes: Exam before conception (if possible), first trimester, and every trimester if retinopathy present. Postpartum exam if DR present.
  • Method: Dilated retinal photography or comprehensive eye examination.
  • Follow-up Intervals: No/minimal DR: every 1-2 years. Any DR: at least annually. Moderate NPDR: review within 12 weeks. Higher-risk patients: at least annually.
  • Management: Optimize glycemic control, BP, and lipids. Fenofibrate may slow progression. Avoid rapid, large HbA1c reductions in severe NPDR or PDR. Smoking cessation is a modifiable risk factor.
Referral Red Flags:
  • Any level of diabetic macular edema
  • Moderate or worse NPDR
  • Any PDR
  • Unexplained vision loss

Gestational Diabetes Mellitus (GDM)

  • Moderate Risk Factors: Ethnicity (Asian, Indian subcontinent, Aboriginal, Torres Strait Islander, Pacific Islander, Māori, Middle Eastern, non-White African), BMI 25-35 kg/m².
  • High Risk Factors: Previous GDM, previously elevated glucose, maternal age ≥ 40, family history of diabetes, BMI > 35 kg/m², previous macrosomia (>4500g or >90th centile), PCOS, corticosteroid/antipsychotic medications.
  • First Trimester Screening (10-14 weeks): Assess risk factors; measure HbA1c if at risk and none in past 12 months. Previous GDM or HbA1c 6.0-6.4% → 75g POGTT prior to 20 weeks (ideally 10-14 weeks). Do not perform POGTT before 10 weeks.
  • 24-28 Weeks: All pregnant women without diabetes already detected undergo 75g 2-hour POGTT.
  • Diagnostic Criteria (ADIPS 2025): FPG ≥ 5.3 mmol/L (updated from 5.1 mmol/L); 1-hour PG ≥ 10.6 mmol/L; 2-hour PG ≥ 9.0-11.0 mmol/L.
  • Overt Diabetes in Pregnancy: Diagnosed any time if FPG ≥ 7.0 mmol/L, 2hPG ≥ 11.1 mmol/L (75g POGTT), and/or HbA1c ≥ 6.5%. Managed similarly to pre-existing diabetes.
  • Postpartum Follow-up: 75g OGTT at 6-12 weeks postpartum. If normal, repeat screening with FBG or HbA1c every 3 years. If planning pregnancy, repeat OGTT annually until conception.

Diabetes Pharmacology & Emergencies

  • Metformin: Reduces hepatic glucose production, decreases intestinal absorption, enhances insulin sensitivity. Unlikely to cause hypoglycemia alone. Can cause GI intolerance and B12 deficiency. Avoid if GFR < 30 mL/min (except specialist supervision). Withhold during acute illness or before surgery/contrast radiography (lactic acidosis risk).
  • Sulfonylureas: Stimulate pancreatic insulin release; weight gain and significant hypoglycemia risk. Avoid glibenclamide/glimepiride with any kidney impairment; reduce gliclazide/glipizide dose in severe impairment. Stop when only clear fluids allowed.
  • DPP-4 Inhibitors: Increase incretin levels; well tolerated, no weight gain. Rare pancreatitis. Avoid saxagliptin, caution with alogliptin in heart failure. Do not combine with GLP-1RA.
  • GLP-1 Receptor Agonists: Cardiovascular/renal benefits in ASCVD or CKD; causes weight loss. GI effects, rare pancreatitis; semaglutide linked to retinopathy worsening. Avoid semaglutide/exenatide if GFR < 30; avoid dulaglutide/liraglutide if GFR < 15.
  • SGLT2 Inhibitors: Inhibit renal glucose reabsorption. Rare DKA (including euglycemic DKA), genitourinary infections. Withhold if acutely unwell; stop at least 4 days before bowel-prep surgery.
  • Insulin Therapy: Initial basal dose (T2DM): long-acting insulin 0.2 units/kg (up to 30 units) SC once daily, same time each day.
  • Perioperative Management: Target glucose 6.1-10 mmol/L during/after surgery. Hold oral hypoglycemics/noninsulin injectables morning of surgery.
  • Hypoglycemia: BGL ≤ 3.9 mmol/L and/or neurogenic/neuroglycopenic symptoms. Severe: BGL < 3.0 mmol/L or requiring third-party assistance. Discuss risk at every visit for insulin/sulfonylurea users; provide sick-day plans. Driving restrictions apply after severe episodes until risk is controlled.
Hyperglycemic Emergency Red Flags (DKA, HHS, Euglycemic DKA):
  • Venous or self-monitored glucose > 15 mmol/L on two occasions with symptoms of metabolic disturbance (polyuria, polydipsia, fatigue, nausea, vomiting, abdominal pain, altered consciousness, ketotic breath).
  • Euglycemic DKA can occur with SGLT2 inhibitors even if glucose < 11 mmol/L — always check blood ketones if unwell.
  • Urgent hospital referral required.
  • Start IV fluid resuscitation (0.9% sodium chloride) and continuous IV insulin infusion (0.1 units/kg/hr). Do not give IV insulin bolus.
  • Stop SGLT2 inhibitors immediately.

Differentiating Type 1 vs. Type 2 Diabetes

Feature Type 1 Diabetes Type 2 Diabetes Monogenic Diabetes
Usual Onset Acute Insidious Variable
Osmotic Symptoms Pronounced Not evident unless severe hyperglycemia Variable
Ketosis May be present at diagnosis, ongoing risk Usually absent, may occur with SGLT2i Common in neonatal forms; rare in others
Obesity Can co-exist; weight loss more usual at diagnosis Often obese (up to 85%) Usually not obese
Insulin Resistance Rare Often present Rare
Family History (parents) 2-4% 80% 90%
Antibodies GAD, IA-2, ZnT8 present in 85-95% Usually absent Not present
C-peptide (non-fasting) Below normal range (< 0.2 nmol/L) Normal or above normal range Normal
  • Key Diagnostic Pointers for Type 1 Diabetes: Acute weight loss (>5% in <4 weeks), blood ketones > 0.5 mmol/L with hyperglycemia (>1.5 mmol/L indicates high risk of decompensation), low C-peptide (<0.2 nmol/L), presence of GAD or IA-2 antibodies, acute onset of polyuria/polydipsia, personal/family history of autoimmune disease.
  • Age of Onset: Most people with Type 1 diabetes are adults (42% between 30-60 years).
  • Management During Diagnostic Uncertainty: Do not delay management of hyperglycemia while awaiting antibody or C-peptide testing. Specialist endocrinology referral is recommended for diagnostic uncertainty.

Presentations

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