Diabetic kidney disease

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

Diabetic kidney disease is a clinical phenotype of persistent albuminuria, reduced filtration or both in a person with diabetes after competing causes have been considered. Glomerular hyperfiltration, intraglomerular pressure, metabolic injury, inflammation and vascular disease contribute. Retinopathy and a gradual course support a diabetic origin, but neither is obligatory. Albuminuria is itself a cardiovascular risk marker and can improve before eGFR changes.

Staging combines eGFR category with albuminuria category because risk rises across both axes. A single abnormal result during infection, dehydration or hyperglycaemia is not enough to label chronic kidney disease; chronicity and repeat testing matter. Conversely, a preserved eGFR does not make substantial albuminuria benign. Trend and rate of decline are more useful than one isolated creatinine.

The central decision is whether this is stable diabetic CKD suitable for layered risk-reduction treatment, an acute change requiring temporary medicine and volume management, or an atypical presentation needing nephrology investigation. Treatment choices are indication led: renin–angiotensin blockade reduces albuminuric progression, SGLT2 inhibitors protect kidneys and heart, and finerenone adds non-steroidal mineralocorticoid-receptor blockade for a defined type 2 population.

Key points

Screen diabetic kidney disease with both estimated glomerular filtration rate and urine albumin-to-creatinine ratio because either may be abnormal while the other remains apparently normal.
Confirm a new moderately raised albumin-to-creatinine ratio on an early-morning sample after excluding urinary infection, menstruation, fever, strenuous exercise and acute decompensation.
Diabetes is not proof of causation: haematuria, abrupt filtration loss, nephrotic syndrome, systemic features or an atypical time course should prompt investigation for non-diabetic kidney disease.
Offer an ACE inhibitor or angiotensin receptor blocker to eligible people with diabetic CKD and albuminuria, titrating to the maximum tolerated dose while monitoring creatinine and potassium.
Never combine an ACE inhibitor with an angiotensin receptor blocker; dual renin–angiotensin blockade increases acute kidney injury and hyperkalaemia without a safe routine role.
An SGLT2 inhibitor may provide kidney and heart protection even when eGFR is too low for a strong glucose-lowering effect; prescribe to the current indication and teach ketone-focused sick-day rules.
Finerenone is an option for selected adults with type 2 diabetes and stage 3 or 4 albuminuric CKD despite optimised standard care, but potassium and renal eligibility determine safe initiation and continuation.
HbA1c becomes less reliable in advanced CKD, anaemia, erythropoietin treatment and dialysis; use glucose or CGM patterns and reduce hypoglycaemia-prone medicines as renal clearance falls.
Kidney protection also includes blood-pressure control, smoking cessation, lipid management, avoidance of nephrotoxins, vaccination, cardiovascular prevention and preparation for renal replacement or supportive care when progression continues.

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

Sustained metabolic injury

Longstanding hyperglycaemia drives glomerular metabolic, inflammatory and structural injury, particularly when diabetes duration and overall exposure are substantial.

Haemodynamic and vascular stress

Intraglomerular pressure, hypertension, smoking and broader vascular disease accelerate albumin leakage and loss of filtration reserve.

Susceptible clinical context

Albuminuria, retinopathy and a gradual eGFR decline support diabetic kidney disease, although their absence does not reliably exclude it.

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

1
Hyperfiltration stresses glomeruli
Early haemodynamic change raises pressure within glomerular capillaries, increasing mechanical strain on the filtration barrier as the process continues.
2
The filtration barrier becomes permeable
Metabolic, inflammatory and vascular injury damages glomerular cells and basement membrane, allowing albumin to pass into urine.
3
Nephron loss progresses
Persistent injury promotes glomerulosclerosis and tubulointerstitial fibrosis, reducing filtration and increasing workload on remaining nephrons while the condition remains active.
4
Cardiorenal risk amplifies
Albuminuria and reduced filtration reflect systemic vascular disease as well as kidney damage, increasing cardiovascular and renal-event risk together.

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

Albuminuric phenotype

Persistent raised urine albumin-to-creatinine ratio may precede eGFR loss and signals renal and cardiovascular risk even when serum creatinine appears normal.

Non-albuminuric decline

Some people with diabetes develop falling eGFR without substantial albuminuria, particularly with vascular disease, ageing or treatment; the absence of albumin does not end evaluation.

Typical gradual progression

Years of diabetes, retinopathy, slowly rising albuminuria and gradual filtration loss support diabetic kidney disease, although the diagnosis remains clinical rather than automatic.

Atypical renal presentationRed flag

Visible or persistent microscopic haematuria, active urine sediment, abrupt creatinine rise, rapid eGFR loss, nephrotic syndrome or systemic inflammation suggests another or additional renal disorder.

Fluid and uraemic featuresRed flag

Oedema, breathlessness, nausea, itch, cognitive change, pericarditic pain or severe fatigue can accompany advanced kidney failure and need urgent severity assessment.

Hyperkalaemia riskRed flag

Muscle weakness, palpitations or syncope may accompany severe potassium elevation, but dangerous hyperkalaemia can be asymptomatic; laboratory surveillance is essential after RAAS-active medicines.

Falling insulin requirement

Recurrent hypoglycaemia or a sudden need for less insulin can reflect declining renal insulin clearance, reduced intake or intercurrent illness rather than spontaneous diabetes remission.

Pregnancy or conception planRed flag

ACE inhibitors, angiotensin receptor blockers and finerenone are unsuitable around pregnancy; early specialist medicine replacement and renal–obstetric planning are required.

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
Quantify albumin loss and assign the albuminuria component of CKD risk.
Interpretation and limitations
Use an early-morning sample to confirm a new moderate elevation, considering infection, menstruation, fever, exercise and marked hyperglycaemia. Persistent albuminuria guides RAAS blockade, cardiorenal treatment and referral.
02
Serum creatinine and estimated glomerular filtration rate
Why
Stage filtration impairment and measure the direction and rate of change.
Interpretation and limitations
Compare serial results rather than a single value. A substantial early change after RAAS blockade, dehydration or SGLT2 initiation requires clinical context, medicine review and repeat testing; rapid decline needs escalation.
03
Serum potassium, bicarbonate and renal profile
Why
Detect treatment-limiting hyperkalaemia, acidosis and other CKD complications.
Interpretation and limitations
Check before and after ACE inhibitor, ARB or finerenone initiation and dose change at the interval required by current guidance. Severe or rising potassium needs urgent confirmation and management, not routine follow-up.
04
Urinalysis and urine microscopy
Why
Look for blood, infection, glycosuria, casts and evidence of a competing renal process.
Interpretation and limitations
Persistent haematuria or active sediment is atypical for uncomplicated diabetic kidney disease and should trigger the appropriate urological or nephrological pathway rather than attribution to diabetes.
05
Renal ultrasound
Why
Assess kidney size, obstruction, asymmetry and structural urinary-tract disease when clinically indicated.
Interpretation and limitations
Use for rapid decline, haematuria, recurrent infection, voiding symptoms or suspected obstruction. Normal imaging does not exclude glomerular disease, and routine scanning is unnecessary in every stable case.
06
HbA1c with glucose or continuous glucose monitoring
Why
Guide safe glycaemic treatment as renal function alters medicine exposure.
Interpretation and limitations
Anaemia, iron treatment, erythropoietin, transfusion and dialysis can distort HbA1c. When values conflict with symptoms or glucose data, act on validated patterns and involve diabetes or laboratory specialists.
07
Full blood count, ferritin and transferrin saturation
Why
Characterise anaemia in established CKD and avoid assuming every low haemoglobin is renal.
Interpretation and limitations
Assess iron deficiency, bleeding, B12 or folate deficiency and inflammation before attributing anaemia to erythropoietin deficiency; use the current renal anaemia pathway for treatment.
08
Calcium, phosphate, alkaline phosphatase and parathyroid hormone
Why
Assess CKD mineral and bone disorder when filtration is sufficiently reduced.
Interpretation and limitations
Interpret as a longitudinal pattern with vitamin D status, fracture risk and CKD stage. Specialist thresholds and treatment vary, so use the current nephrology protocol.
09
Kidney failure risk estimate
Why
Combine validated variables to support referral and preparation decisions in eligible CKD.
Interpretation and limitations
Use a locally supported validated equation and current NICE referral criteria. The score complements clinical red flags, rate of decline and patient preference and must not delay urgent referral.

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

Hypertensive kidney disease

Longstanding severe hypertension with little albuminuria and prominent vascular disease may indicate a mainly hypertensive process, although both causes often coexist.

Primary glomerular disease

Active urine sediment, abrupt heavy proteinuria, oedema or rapid decline is atypical and should prompt nephrology assessment for another glomerular disorder.

Acute kidney injury

A sudden creatinine rise during dehydration, infection or medicine change lacks chronicity and requires immediate cause review rather than relabelling as diabetic progression.

Obstructive or structural disease

Urinary symptoms, hydronephrosis or asymmetric kidneys suggest obstruction or another structural diagnosis that albumin and eGFR trends alone cannot establish.

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

01ConfirmNew albuminuria or reduced eGFRFirst stepRoutine diabetes review identifies an abnormal urine albumin-to-creatinine ratio, eGFR or creatinine trend.

1Check prior results, volume status, acute illness, urinary infection, recent exercise, medicines and blood pressure to distinguish chronic disease from a transient or acute change.
2Repeat albuminuria using the recommended early-morning strategy and establish eGFR chronicity, while obtaining urinalysis and targeted tests for atypical features.
3Stage risk using both albuminuria and filtration categories, communicate that kidney and cardiovascular risks are linked, and record a personalised monitoring interval.
4Refer or seek nephrology advice for rapid progression, heavy albuminuria, haematuria, resistant hypertension, uncertain cause, electrolyte difficulty or high kidney-failure risk under current NICE criteria.

02ProtectLayered diabetic CKD treatmentConfirmed chronic diabetic kidney disease without an acute contraindication to disease-modifying treatment.

1Optimise blood pressure and, when albuminuria is present and eligibility is met, start an ACE inhibitor or ARB with baseline potassium, creatinine and pregnancy assessment.
2Offer an SGLT2 inhibitor for the current licensed CKD, heart-failure and diabetes indication, explaining that kidney benefit may persist despite limited glucose lowering at lower eGFR.
3For eligible type 2 stage 3 or 4 albuminuric CKD despite optimised standard care, consider finerenone with product-specific potassium and renal checks and specialist or formulary support.
4Integrate individual glucose treatment, statin and cardiovascular prevention, smoking support, nutrition, weight and exercise while avoiding combinations or targets that provoke hypoglycaemia or malnutrition.
5Review albuminuria, eGFR, potassium, blood pressure, symptoms and adherence, preserving beneficial therapy when a small expected haemodynamic change is clinically safe and investigating larger deterioration.

03AcuteIllness or acute kidney injuryVomiting, diarrhoea, sepsis, poor intake, hypotension, oliguria or an unexpected creatinine rise in someone receiving kidney-active diabetes medicines.

1Assess ABCDE, fluid balance, sepsis, obstruction, glucose and blood ketones; obtain renal profile and ECG promptly when potassium disturbance or severe AKI is possible.
2Apply the written sick-day plan and local AKI guidance to pause SGLT2 inhibitor, metformin and haemodynamically unsafe medicines temporarily, while never omitting essential basal insulin in type 1 diabetes.
3Treat the precipitant, restore appropriate circulation, avoid nephrotoxins and contrast where possible, and obtain renal or critical-care support for refractory electrolyte, fluid, acid-base or uraemic complications.
4Restart each medicine only after clinical, intake and renal recovery against its current indication, with planned repeat biochemistry; a blanket discharge instruction to restart everything is unsafe.

04ProgressAdvanced CKD and kidney failure planningSustained filtration decline, high predicted kidney-failure risk or symptoms despite optimised protective treatment.

1Refer early enough for shared decisions, diagnostic review and management of anaemia, acidosis, mineral-bone disorder, nutrition, fluid and cardiovascular risk.
2Review all diabetes medicines for renal dosing and hypoglycaemia, interpret HbA1c cautiously and use glucose patterns as insulin clearance and appetite change.
3Discuss transplantation, dialysis modalities and comprehensive conservative kidney management in language and formats the person can use, including family or advocates when desired.
4Create an anticipatory plan for access, vaccination, symptom control, acute deterioration and treatment ceilings, revisiting choices as circumstances and preferences evolve.

Key medicines and prescribing safety5 treatments · regimens, roles and cautions

Reduces intraglomerular pressure, albuminuria and progression risk in eligible diabetic CKD and treats hypertension.

ACE inhibitor

Start at a low licensed dose and titrate toward the maximum tolerated dose with laboratory monitoring.

Check creatinine and potassium before and after initiation or titration. Avoid pregnancy, bilateral significant renal artery stenosis and combination with an ARB; pause during haemodynamic AKI according to the sick-day plan.

Provides renin–angiotensin system kidney protection when an ACE inhibitor is indicated but not tolerated.

Angiotensin receptor blocker

Use a licensed once-daily regimen and titrate with blood pressure, creatinine and potassium review.

Do not combine with an ACE inhibitor. Hyperkalaemia, AKI, hypotension and pregnancy restrictions remain; angioedema history and product details require individual review.

Slows CKD progression and reduces heart-failure events through effects extending beyond glucose lowering.

SGLT2 inhibitor

Use the licensed cardiorenal dose for the selected product when current eGFR and indication permit.

Teach blood-ketone sick-day rules and pause during acute serious illness or major surgery. Review dehydration, genital infection and DKA risk; do not use routinely for type 1 diabetes.

Adds non-steroidal mineralocorticoid-receptor blockade for eligible type 2 diabetes with stage 3 or 4 albuminuric CKD.

Finerenone

Select the licensed starting strength from eGFR and potassium, then adjust only after repeat tests.

Hyperkalaemia is dose limiting. Apply NICE and current product criteria, avoid strong interacting inhibitors and pregnancy, and do not start or continue outside the specified potassium and renal boundaries.

Improves glycaemia and weight with product-specific cardiovascular and kidney outcome evidence alongside foundational CKD therapy.

GLP-1 receptor agonist or tirzepatide

Initiate and titrate at licensed intervals when the current type 2 diabetes pathway indicates treatment.

Gastrointestinal fluid loss can precipitate AKI; counsel about pancreatitis and pregnancy, protect nutrition and muscle, and reduce concurrent insulin or sulfonylurea cautiously rather than abruptly.

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

Progressive kidney failure

Continuing nephron loss can lead to advanced chronic kidney disease, uraemic symptoms and eventual need for renal replacement planning.

Cardiovascular disease

Albuminuria and reduced eGFR markedly increase risks of coronary disease, stroke, peripheral arterial disease and heart failure.

Hyperkalaemia and acute injury

Reduced excretory reserve and interacting cardiorenal medicines make potassium accumulation and illness-related acute kidney injury more likely.

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

Measure eGFR and urine albumin-to-creatinine ratio at the interval determined by the combined risk category and more often after acute illness or rapid change.
Check creatinine and potassium before and after ACE inhibitor, ARB or finerenone initiation and titration using current product and renal guidance; act promptly on severe or rising results.
Review blood pressure with postural symptoms, home readings where useful and adherence, avoiding aggressive lowering that causes falls, renal hypoperfusion or treatment withdrawal.
Track glucose, CGM and hypoglycaemia as eGFR falls, reducing insulin and secretagogue exposure when clearance or intake decreases and recognising when HbA1c is distorted.
Ask about oedema, breathlessness, urine output, nausea, pruritus, sleep, cognition, appetite and functional decline to identify fluid overload or uraemic burden before laboratory review alone would do so.
Audit sick-day understanding, NSAID and over-the-counter use, pregnancy plans, vaccination, foot health and cardiovascular prevention at medicine reviews.
For advanced CKD, monitor anaemia, bicarbonate and mineral-bone indices through the renal pathway and document dialysis, transplantation or conservative-care planning milestones.

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

Use both kidney markers

Albuminuria and eGFR describe different dimensions of injury. Testing only creatinine misses early albuminuric disease, while testing only urine misses non-albuminuric filtration loss.

A dip is not always toxicity

RAAS and SGLT2 treatments can cause an early haemodynamic eGFR change. Judge magnitude, volume status, potassium and trajectory before stopping a drug that may protect long-term function.

Glucose effect is not kidney effect

At lower eGFR an SGLT2 inhibitor may lower HbA1c little yet retain cardiorenal value. Continue or stop according to indication and safety, not glucose appearance alone.

Albumin varies for many reasons

Exercise, infection, fever, menstruation and acute hyperglycaemia can raise a sample transiently. Confirmation prevents a chronic label from one unstable measurement.

Diabetes can be a distraction

Haematuria, sudden nephrotic protein loss or rapid decline deserves a differential diagnosis even after decades of diabetes; glomerular, obstructive and vascular disease can coexist.

Kidney failure changes diabetes data

Reduced insulin clearance increases hypoglycaemia, while anaemia and erythropoietin alter HbA1c. Treatment intensity should follow reliable glucose and patient outcomes rather than a misleading average.

Potassium determines access

Hyperkalaemia can block RAAS blockade or finerenone. Review diet, constipation, acidosis and interacting medicines and involve renal teams rather than abandoning all protective therapy automatically.

Pregnancy planning is renal care

Potentially fetotoxic kidney medicines must be replaced before conception where possible, while albuminuria, blood pressure and renal reserve guide specialist maternal risk planning.

11Common pitfallsFrequent interpretation and management errors.

01
Diagnosing diabetic nephropathy from one albumin result obtained during urinary infection.
02
Assuming every decline in a person with diabetes is caused by diabetes.
03
Combining an ACE inhibitor and an angiotensin receptor blocker.
04
Stopping an SGLT2 inhibitor solely because its glucose-lowering effect has weakened at lower eGFR.
05
Starting finerenone without baseline and follow-up potassium planning.
06
Intensifying insulin from a misleading HbA1c despite recurrent hypoglycaemia in advanced CKD.
07
Restarting metformin, SGLT2 treatment and RAAS blockade automatically before recovery from acute illness.
08
Waiting for dialysis-level eGFR before discussing nephrology referral and kidney replacement preferences.