Type 2 Diabetes Mellitus

Relative or absolute insulin deficiency causing hyperglycaemia. Type 1 (~10%): usually young, rapid onset, thin, insulin-deficient, ketosis-prone. Type 2 (~85-90%): usually >40y, insidious/mild or asymptomatic, often obese, insulin-resistant, associated with metabolic syndrome/PCOS/fatty liver. This page focuses on type 2.

• Specific symptoms: polyuria, polydipsia, weight loss, polyphagia, tiredness/malaise/fatigue, nocturia
• Systems review: cardiovascular (chest pain, dyspnoea), urinary function, sexual function, neurological (tingling in feet/hands), vision (blurred), infection tendency (skin, urine, genital), genital itching
• Family history, medications, smoking/alcohol, obstetric history, physical activity, nutrition/eating habits
• DxT pattern: thirst + polyuria + weight loss → type 1 diabetes (typically an unwell child/young person with a high finger-prick glucose — this is a medical emergency)

• Age >40 years
• Family history
• Overweight/obesity, sedentary lifestyle
• History of gestational diabetes or pancreatitis
• Polycystic ovarian syndrome
• Hypertension/ischaemic heart disease
• Medication causing hyperglycaemia (thiazides, high-dose oestrogen, corticosteroids)
• High-prevalence ethnic groups: Aboriginal and Torres Strait Islander, Pacific Islander, Indian subcontinent, Chinese, Afro-Caribbean

AUSDRISK every 3 years from age 40; if score ≥12 do fasting glucose or HbA1c. Screen earlier/more often (annually in very high-risk groups) if: known prediabetes, age >40 (or >30 with risk factors: first-degree relative, BMI >30, high-prevalence ethnicity), age >18 in Aboriginal and Torres Strait Islander people, previous gestational diabetes, long-term steroids/antipsychotics, PCOS with overweight, previous CV event.

• General inspection including skin; BMI (weight/height); waist circumference; visual acuity
• Blood pressure — lying and standing
• Peripheral neuropathy: tendon reflexes, sensation (e.g. cotton wool, 10g monofilament)
• Urinalysis: glucose, albumin, ketones, nitrites

• Symptomatic (≥2 of polydipsia, polyuria, frequent skin infections or genital thrush): fasting venous glucose ≥7.0 mmol/L, OR random venous glucose (≥2h after eating) ≥11.1 mmol/L, OR HbA1c >6.5% (>48 mmol/mol)
• Asymptomatic: at least two separate elevated values (fasting, ≥2h postprandial, or the two OGTT values) on different occasions
• Uncertain/borderline range (fasting or random venous glucose 5.5-11.0 mmol/L in a symptomatic patient or one with risk factors): perform an OGTT — 2-hour value ≥11.1 mmol/L confirms diabetes, <7.8 makes it unlikely, 7.8-11 = impaired glucose tolerance
• Avoid glucose tolerance tests where diagnosis can be made on symptoms plus fasting/random glucose or HbA1c — an OGTT carries a small risk of precipitating hyperosmolar coma
• Prediabetes = impaired fasting glucose (6.1-6.9 mmol/L) or impaired glucose tolerance — not itself a reason to start medication, but raises urgency of lifestyle change
• Urinalysis for glucose is unreliable for diagnosis — renal glucose threshold varies between patients

• Fasting or random venous blood glucose — Initial diagnostic test
• HbA1c — Diagnosis and 3-6 monthly monitoring of control (reflects mean glucose over 2-3 months)
• Oral glucose tolerance test (OGTT) — Only for true borderline cases, and for diagnosing gestational diabetes (75g OGTT at 24-28 weeks)
• Lipids (total/HDL/LDL cholesterol, triglycerides) — CV risk stratification and management target
• Kidney function (serum urea/creatinine, eGFR) — Baseline, monitor nephropathy and drug safety (e.g. metformin, SGLT2 inhibitors)
• Urine albumin:creatinine ratio (ACR), first morning sample — Screens for diabetic nephropathy — microalbuminuria is an early, reversible marker; dipstick is unreliable and 24h collection impractical in general practice
• ECG — Baseline cardiovascular assessment

• HbA1c — Every 3-6 months
• Blood glucose self-monitoring — Mainly useful if on insulin (fasting and postprandial); not routinely needed on oral agents alone — HbA1c preferred
• Urine ACR — Annual nephropathy screen
• Lipids — Every 12 months
• Fundoscopy / retinal photography — Every 1-2 years via direct ophthalmoscopy (dilated pupils), retinal photography, or fluorescein angiography if needed
• Foot examination (including footwear, injection sites) — Annually, and opportunistically — foot problems are among the commonest diabetes complications

Cardiovascular disease causes most of the excess morbidity/mortality in type 2 diabetes. Diabetes often co-exists with obesity, hypertension and dyslipidaemia (the 'deadly quartet' / metabolic syndrome).

• GP's main objectives: prevent cardiovascular disease and other complications
• Core targets: reduce lifestyle risks (weight, smoking, inactivity); glycaemic control (HbA1c usually ≤7%); blood pressure control (<140/90, lower if tolerated — has more mortality benefit than glucose control alone); blood lipid control
• NEAT mnemonic for lifestyle review: Nutrition, Exercise, Avoidance of toxins (alcohol, tobacco, salt, sugar, illicit drugs), Tranquillity (rest, stress reduction)
• Remission of established type 2 diabetes is a realistic aim in general practice using intensive dietary measures for 3 months followed by structured weight-loss support (DiRECT trial)

In prediabetes, medication is not indicated — focus on lifestyle. In confirmed type 2 diabetes, trial diet and exercise first (most symptoms improve within 1-4 weeks); if unsatisfactory control persists after 3-6 months, add an oral hypoglycaemic agent.

• Diet: protein 10-20%, fat 20-40%, carbohydrate 35-60%; reduce saturated fat, added sugar and alcohol; follow glycaemic index; increase vegetables/fruit/wholegrain; special diabetic foods not necessary; low-carb diets are an option
• Exercise: at least 150 minutes/week (e.g. 30 min, 3+ times/week, ideally daily) — brisk walking, jogging, swimming, aerobics; start gradually and increase pace
• Weight loss support, ideally with a dietitian / diabetes education service
• Smoking cessation, alcohol ≤2 standard drinks/day
• Immunisation: influenza, pneumococcus, COVID-19, dTpa

Preferred antihypertensives: ACE inhibitors/ARBs (first-line if albuminuria present) and calcium-channel blockers; target <140/90 (lower if tolerated, stricter with proteinuria). Try non-pharmacological measures first. For dyslipidaemia, preferred agents are HMG-CoA reductase inhibitors (statins) ± resins for hypercholesterolaemia, fibrates/resins for mixed hyperlipidaemia; non-pharmacological measures tried first. Aspirin is not routinely indicated unless there has been a prior cardiovascular event (then 75-150mg/day).

1. 1. Lifestyle (diet + exercise) trial for 3-6 months first in type 2 diabetes
2. 2. If HbA1c target not met: start metformin (first-line) — usual starting dose 500mg once or twice daily
3. 3. If target not met after further 3-6 months: add a second agent — SGLT2 inhibitor or GLP-1 receptor agonist are now preferred second-line (particularly with cardiovascular disease, heart failure, multiple CV risk factors or kidney disease); DPP-4 inhibitors are an option where CV/renal risk is low or SGLT2/GLP-1 not tolerated; sulfonylureas and glitazones are valid but now largely superseded given they lack proven CV/renal benefit
4. 4. Insulin may be required at any stage, particularly if symptomatic hyperglycaemia or HbA1c remains well above target — for less experienced GPs, shared care with an endocrinologist is recommended
5. Review the need for continued oral therapy after 3 months of treatment; avoid prescribing an oral hypoglycaemic agent prematurely without a genuine lifestyle trial first

Four metabolic emergencies to recognise promptly in a person with diabetes.

• Erectile dysfunction affects up to 50% of men with type 2 diabetes over 40 — may be macrovascular, autonomic-neuropathic or psychological; phosphodiesterase inhibitors appropriate if organic and not on nitrates
• Female sexual dysfunction — reduced vaginal lubrication from autonomic dysfunction; lubricants, education, reassurance
• Postural hypotension (autonomic neuropathy ± antihypertensive/anti-anginal medication) — may need relaxed BP targets, compression stockings, occasionally fludrocortisone if severe
• Gastroparesis — fullness, dysphagia, reflux, recurrent nausea/vomiting after meals; dietary modification or domperidone/cisapride/erythromycin
• Driving — hypoglycaemia and visual complications are the main risks; diet-controlled patients unrestricted, insulin-treated patients may need a conditional licence with periodic review (see Austroads 'Assessing Fitness to Drive')
• Contraception — long-acting reversibles (Implanon, Mirena) or combined OCP are appropriate; consider coexisting PCOS
• Diabetes-related stigma and discrimination are common (up to 4/5 report experiencing it) — empathetic care has a measurable positive effect on HbA1c/LDL target attainment

• Type 1 diabetes — specialist evaluation then 1-2 yearly review
• Type 2 diabetes: consider referral for young people, those requiring insulin, or those with complications (level depends on GP's comfort/experience)
• Treatable complications: retinopathy, nephropathy, neuropathy (test annually)
• Foot ulcer not healing within 6 weeks, or any pus/infection in a diabetic foot

• Teach recognition and self-treatment of hypoglycaemia to all patients on insulin or sulfonylureas; 'recurrent hypoglycaemia begets hypoglycaemic unawareness' — ask about symptoms often
• Instruct patients on SGLT2 inhibitors to withhold the medication when acutely unwell, fasting, or around surgery (euglycaemic DKA risk)
• Foot care education — check footwear, inspect feet, treat minor cuts/infections promptly
• Sick-day guidance: do not stop insulin during illness (opposite advice to SGLT2 inhibitors); monitor more closely when unwell
• Arrange structured follow-up: 3-monthly review (symptoms, weight/BMI, BP, urine, self-monitoring, exercise, HbA1c at least 6-monthly) and annual review (full history, examination incl. eyes/feet/pulses, biochemistry incl. lipids)

• Many cases of type 2 diabetes remain undiagnosed — maintain vigilance, especially in at-risk groups
• Hyperglycaemia is a common cause of tiredness in the elderly with type 2 diabetes — consider long-acting insulin to improve symptoms if very tired
• If a person with diabetes (particularly type 1) is very drowsy and looks sick, consider ketoacidosis first and withhold SGLT2 inhibitors
• Management is a team effort — family, nurse educator, podiatrist, dietitian, GP, and sometimes endocrinologist or domiciliary nursing
• 'Never let the sun go down on pus in a diabetic foot' — admit to hospital
• Prevention/detection of coronary heart disease should be integral to every consultation