Diabetic kidney disease

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Chronic hyperglycaemia, glomerular hypertension, inflammation and fibrosis contribute to diabetic kidney disease, but clinical expression is varied. Traditional progression from hyperfiltration to albuminuria and falling filtration is not universal. Some people develop reduced eGFR without prominent albuminuria, while others have severe albumin loss with preserved filtration. Both ACR and eGFR therefore belong in routine surveillance.

Attribution matters because diabetes does not protect against another renal diagnosis. Retinopathy and long-standing diabetes support, but do not prove, diabetic kidney disease. Haematuria with casts, abrupt nephrotic syndrome, rapidly changing function, refractory hypertension, systemic inflammation or a monoclonal-protein signal should trigger nephrology discussion and sometimes biopsy.

Modern care combines therapies with complementary benefits while monitoring the shared risks of hypotension, acute kidney injury and potassium disturbance. Treatment should use the current NICE indications, product characteristics and local formulary. Frailty, type of diabetes, pregnancy potential, recurrent genital infection, ketoacidosis risk and the patient's capacity to follow sick-day instructions materially affect choices.

Key points

Diabetic kidney disease is identified by persistent albuminuria, reduced eGFR or both in a person with diabetes after excluding important alternative explanations.
Measure urine ACR as well as creatinine because substantial albuminuric risk can exist while eGFR remains normal, and non-albuminuric kidney impairment also occurs.
Confirm a new abnormal ACR when clinically stable; infection, menstruation, exercise, fever, severe hyperglycaemia and decompensated heart failure can cause transient elevation.
Rapid eGFR decline, active sediment, systemic features, short diabetes duration or proteinuria out of proportion to other microvascular disease should prompt reconsideration of cause.
Kidney protection is layered: glycaemic individualisation, blood-pressure control, ACE inhibitor or ARB for indicated albuminuria, SGLT2 inhibition where eligible, lipid care and smoking cessation.
Finerenone is a NICE option for specified adults with stage 3 or 4 albuminuric CKD associated with type 2 diabetes despite optimised standard care, with potassium-led selection and monitoring.
An early eGFR dip can accompany effective haemodynamic therapy, but excessive decline, hypovolaemia or hyperkalaemia needs prompt review rather than automatic continuation.
Sick-day and perioperative plans must be medicine-specific; indiscriminate stopping or restarting can create hyperglycaemia, ketoacidosis, fluid overload or loss of protection.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Chronic metabolic injury

Chronic hyperglycaemia contributes to diabetic kidney injury over time, although clinical expression varies and the traditional progression sequence is not universal.

Intraglomerular hypertension

Raised pressure within glomeruli contributes to diabetic kidney disease and may present initially as hyperfiltration before albuminuria or falling eGFR.

Susceptibility and progression factors

Long-standing diabetes, retinopathy, hypertension and persistent albuminuria support diabetic kidney disease, but do not prove causation and progression remains variable.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Variable hyperfiltration pathway
Hyperfiltration can precede albuminuria and falling filtration, but this traditional sequence is not universal in diabetic kidney disease.
2
Albuminuric expression
Some people develop substantial albumin loss despite preserved filtration; urine ACR therefore identifies risk that creatinine testing alone can miss.
3
Non-albuminuric expression
Other people develop reduced eGFR without prominent albuminuria, so normal dipstick findings do not exclude progressive diabetic kidney impairment.
4
Inflammation and fibrosis
Chronic inflammation and fibrosis contribute to declining kidney function, but individual clinical expression and progression remain variable.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Albuminuric phenotype

Persistent raised urine ACR may be the earliest clinical marker and independently predicts kidney and cardiovascular events.

Falling filtration

A sustained eGFR decline can occur with little albuminuria and should not be dismissed because dipstick testing is negative.

Atypical renal pictureRed flag

Active urinary sediment, abrupt nephrosis, rapid decline or systemic illness suggests non-diabetic or superimposed kidney disease.

Volume and potassium complicationRed flag

Weakness, arrhythmia, hypotension, oliguria or pulmonary oedema may reflect medicine interaction, acute illness or advanced CKD.

Euglycaemic ketoacidosisRed flag

Nausea, abdominal pain, deep breathing and malaise during fasting or illness on an SGLT2 inhibitor require blood ketones despite near-normal glucose.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Urine albumin-to-creatinine ratioFirst step
Why
Detect and grade albuminuria using a standard quantitative measure.
Interpretation and limitations
Confirm an unexpected low-level elevation on an early-morning sample when stable; very high or rapidly rising values warrant accelerated review.
02
Serial creatinine and eGFR
Why
Establish CKD stage and rate of functional change.
Interpretation and limitations
Compare several values over time and annotate acute illness or medicine initiation; an isolated eGFR cannot distinguish chronic progression from acute kidney injury.
03
Urinalysis and urine microscopy
Why
Look for blood, infection and active glomerular sediment.
Interpretation and limitations
Persistent haematuria, red-cell casts or disproportionate non-albumin protein should shift attention towards another renal process.
04
HbA1c and cardiovascular risk profile
Why
Assess modifiable metabolic risk without reducing renal assessment to glucose alone.
Interpretation and limitations
Interpret HbA1c cautiously in advanced CKD, anaemia, altered red-cell survival or recent transfusion; individual targets should balance benefit and hypoglycaemia.
05
Potassium, bicarbonate and medicine review
Why
Identify treatment constraints and CKD complications before adding kidney-protective agents.
Interpretation and limitations
Hyperkalaemia may reflect RAAS blockade, finerenone, acidosis, constipation, acute injury or diet and should be addressed systematically rather than reflexively abandoning protection.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Primary glomerulonephritis

Dysmorphic haematuria, casts, abrupt nephrotic syndrome, systemic inflammation or rapid decline out of proportion to the diabetic history supports biopsy-led glomerular assessment.

Renovascular disease

Abrupt resistant hypertension, asymmetric kidneys, flash pulmonary oedema or a large creatinine change after renin–angiotensin blockade suggests renal artery disease.

Urinary obstruction

Voiding symptoms, retention, pelvic disease or hydronephrosis indicate post-renal dysfunction, which diabetes-related autonomic neuropathy can make relatively painless.

Medicine-related or haemodynamic AKI

An acute illness, volume change or newly accumulated medicine with a rapid creatinine trajectory favours superimposed AKI rather than steady diabetic progression.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01ScreenFind kidney involvement before symptomsFirst stepA person with diabetes attends planned review.

1Measure urine ACR and serum creatinine/eGFR at the interval specified for diabetes type and previous results.
2Repeat a new ACR abnormality under stable conditions and compare eGFR with earlier values to establish persistence and slope.
3Stage combined G and A categories, communicate cardiovascular as well as renal risk, and assign ownership for follow-up.

02ChallengeCheck whether diabetes explains the patternKidney abnormalities are severe, abrupt or otherwise atypical.

1Review diabetes duration, retinopathy, urine sediment, systemic symptoms, medicines, obstruction risk and family history.
2Investigate plausible alternatives such as glomerulonephritis, infection, paraproteinaemia or renovascular disease rather than using a fixed indiscriminate panel.
3Seek nephrology advice for rapid progression, marked proteinuria, haematuria of renal origin, resistant hypertension or diagnostic uncertainty.

03LayerBuild protective treatment safelyPersistent diabetic CKD is established and acute illness has been excluded.

1Optimise lifestyle, blood pressure, glycaemia and lipid management with shared targets appropriate to frailty and comorbidity.
2Use ACE inhibition or ARB and an eligible SGLT2 inhibitor through current NICE guidance, sequencing changes so haemodynamic and electrolyte effects remain interpretable.
3For eligible stage 3 or 4 albuminuric CKD in type 2 diabetes, consider finerenone after optimised standard care with baseline and scheduled potassium checks.

04ProtectManage acute interruption and restartMajor surgery, acute serious illness, fasting, dehydration or suspected ketoacidosis occurs.

1Apply the local sick-day and perioperative plan, checking volume, creatinine, electrolytes, glucose and blood ketones where indicated.
2Stop an SGLT2 inhibitor immediately when DKA is suspected or diagnosed and treat through the emergency protocol; do not rely on glucose concentration.
3Restart paused kidney-protective medicines only after the acute driver resolves and clinical, renal, potassium and ketone criteria are satisfied, with clear responsibility.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

Reduces kidney progression and cardiovascular events through benefits extending beyond glucose lowering in eligible adults.

SGLT2 inhibitor for eligible type 2 diabetes and CKD

Choose the licensed product and dose from the current NICE recommendation, local formulary, eGFR indication and SmPC; counsel before initiation rather than extrapolating between agents.

Explain genital infection, volume depletion and rare ketoacidosis. Interrupt for major surgery or acute serious illness, monitor blood ketones, and restart only when stable with normal ketones; avoid use for type 1 diabetes outside specialist governance.

Adds non-steroidal mineralocorticoid-receptor blockade to reduce kidney and cardiovascular risk in the appraised population.

Finerenone

Use within NICE TA877 for eligible stage 3 or 4 albuminuric CKD associated with type 2 diabetes after optimised standard care; select and adjust dose using current potassium, eGFR and SmPC rules.

Do not start outside potassium and eGFR criteria. Recheck potassium after initiation and changes, review interacting CYP3A4 medicines and other potassium-raising agents, and pause or discontinue through the live algorithm when hyperkalaemia develops.

NICE foundational treatment for indicated albuminuric diabetic CKD, reducing intraglomerular pressure and renal and cardiovascular risk alongside blood-pressure and other cardiorenal care.

ACE inhibitor or angiotensin-receptor blocker

For an adult with CKD and diabetes and ACR at least 3 mg/mmol, select one ACE inhibitor or one ARB and titrate to the highest licensed dose tolerated, using the chosen product's BNF or SmPC regimen; there is no single class-wide milligram dose.

Check potassium and eGFR before treatment and 1–2 weeks after starting and after every dose increase. Do not combine ACE inhibitor with ARB. Do not routinely start if pretreatment potassium is above 5.0 mmol/L; stop if potassium rises to at least 6.0 mmol/L after other potassium-raising medicines have been discontinued. If eGFR falls at least 25% or creatinine rises at least 30%, assess volume depletion, NSAIDs and other causes, then reduce or stop if none is found. Avoid when planning pregnancy unless essential after documented benefit-risk discussion; stop promptly when pregnancy is diagnosed and arrange a suitable alternative.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Progressive kidney failure

Continuing nephron loss can advance from albuminuric or non-albuminuric CKD to symptomatic kidney failure and replacement-therapy planning.

Cardiovascular and heart-failure events

Albuminuria and reduced filtration mark widespread vascular risk, while sodium retention and shared metabolic disease increase heart-failure and atherosclerotic events.

Hyperkalaemia and volume overload

Advanced renal impairment, acidosis and protective haemodynamic medicines can combine to raise potassium, while impaired sodium excretion promotes oedema and breathlessness.

Advanced CKD syndromes

Loss of endocrine and excretory function contributes to anaemia, acidosis and mineral-bone disorder, each adding fatigue, fracture and cardiovascular burden.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record ACR and eGFR together because improvement or deterioration in either axis changes prognosis and referral decisions.
Check blood pressure, postural symptoms and volume status after adding haemodynamically active treatment, especially in frailty or concurrent diuretic use.
Measure creatinine and potassium at the interval required after ACE inhibitor, ARB or finerenone initiation and dose alteration.
Review HbA1c with hypoglycaemia history, glucose monitoring and renal clearance of medicines rather than pursuing a uniform numerical target.
Reinforce SGLT2 sick-day, fasting and perioperative instructions at medicine reviews, not only when first prescribed.
Escalate nephrology planning as kidney-failure risk rises, including anaemia, acidosis, mineral-bone and replacement-therapy preparation.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

ACR and eGFR are complementary

Normal filtration does not neutralise albuminuric risk, and a negative dipstick does not exclude non-albuminuric diabetic CKD.

A dip can be haemodynamic

A modest early eGFR fall after protective therapy can reflect reduced intraglomerular pressure, but trajectory and clinical state determine acceptability.

Near-normal glucose can mislead

SGLT2-associated ketoacidosis may be euglycaemic, making blood ketones and acid–base assessment crucial during compatible illness.

Finerenone is not ordinary spironolactone

Its evidence, indication and dosing algorithm are product-specific and remain constrained by potassium and renal function.

Retinopathy is supporting evidence

Its presence increases plausibility but does not remove the need to investigate a strikingly atypical kidney presentation.

11Common pitfallsFrequent interpretation and management errors.

01
Screening with creatinine alone and missing clinically important albuminuria.
02
Diagnosing diabetic nephropathy solely because diabetes appears on the problem list.
03
Combining an ACE inhibitor with an ARB in pursuit of further proteinuria reduction.
04
Missing SGLT2-associated ketoacidosis because capillary glucose is not very high.
05
Starting finerenone without confirming its NICE population, baseline potassium and follow-up capacity.
06
Stopping protective therapy during illness but never arranging a safe restart review.