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Type 2 diabetes — complications

TL;DR — T2D complications are vascular, neurological, metabolic and psychosocial, and several may already be present at diagnosis. Cardiovascular disease and CKD dominate mortality and high-cost outcomes; retinopathy, neuropathy and foot disease drive blindness, pain, ulceration and amputation. Risk is not determined by HbA1c alone: blood pressure, lipids, smoking, kidney function, duration, age at diagnosis and social access matter (Rawshani 2017, PMID 28402770). SGLT2 inhibitors and GLP-1 receptor agonists now prevent organ outcomes beyond their glucose effects (Palmer 2021, PMID 33441402).

Complication map

Domain Manifestations Surveillance anchor
Macrovascular Coronary disease, stroke, peripheral artery disease Global CV-risk assessment
Kidney Albuminuria, eGFR loss, kidney failure UACR + eGFR
Eye Non-proliferative/proliferative retinopathy, macular oedema Dilated retinal examination/imaging
Nerve Distal symmetric, autonomic, focal neuropathies Symptoms, feet, autonomic review
Foot Ulcer, infection, Charcot change, amputation Skin, pulses, sensation, footwear
Heart failure Preserved or reduced EF Symptoms/signs; natriuretic/imaging as indicated
Liver MASLD/MASH, fibrosis/cirrhosis Risk-stratified fibrosis assessment
Cognitive/mental Depression, distress, cognitive decline Clinical screening and support

Cardiovascular disease

Risk-factor control can markedly narrow excess risk, but residual risk persists and younger onset lengthens exposure (Rawshani 2017, PMID 28402770; Nanayakkara 2021, PMID 33313987).

Intervention axis Outcome evidence
Glycaemia early UKPDS legacy for MI and mortality (Adler 2024, PMID 38772405)
SGLT2 inhibitor HF and kidney outcomes; CV death in EMPA-REG (Zinman 2015, PMID 26378978)
GLP-1RA MACE reduction across multiple CVOTs (Kristensen 2019, PMID 31422062)
Blood pressure Reduces vascular and kidney risk
Lipids Statin-based prevention central
Smoking cessation Reduces broad vascular and mortality risk

Diabetic kidney disease

Albuminuria and eGFR capture partly different risk. Normal albumin excretion does not exclude progressive eGFR loss, and a high UACR can coexist with preserved filtration.

Stage signal Meaning Action frame
UACR ≥30 mg/g Increased albumin excretion Confirm persistence; optimise pressure/organ protection
eGFR <60 mL/min/1.73m² CKD threshold if persistent Dose review and CKD management
Rapid eGFR decline High-risk trajectory Investigate reversible/non-diabetic causes
Resistant hypertension/active sediment Atypical for uncomplicated DKD Consider alternate kidney disease

CREDENCE reduced a kidney-failure composite by 30% in albuminuric diabetic kidney disease (Perkovic 2019, PMID 30990260). FLOW established kidney benefit for semaglutide in T2D with CKD (Perkovic 2024, PMID 38785209).

Retinopathy

Retinopathy can be present at T2D diagnosis, reflecting years of undetected hyperglycaemia (Cai 2023, PMID 36286346). Global diabetic-retinopathy burden is projected to increase through 2045 (Teo 2021, PMID 33940045).

Rapid glycaemic improvement can transiently worsen retinopathy in high-risk eyes; SUSTAIN-6 renewed attention to this phenomenon (Marso 2016, PMID 27633186). This argues for eye-risk assessment and monitored improvement, not maintaining hyperglycaemia.

Neuropathy and foot disease

Finding Risk implication
Loss of protective sensation Ulcer risk
Deformity/callus Pressure concentration
Absent pulses Ischaemia and impaired healing
Prior ulcer/amputation Highest recurrence group
Warm swollen relatively painless foot Possible Charcot emergency
Spreading erythema/systemic illness Severe infection

Neuropathy includes pain, numbness, balance impairment, gastroparesis, erectile dysfunction, bladder dysfunction and cardiovascular autonomic disease. Foot outcomes arise from interaction among neuropathy, ischaemia, pressure, infection and access to rapid care (ADA 2026, PMID 41358886).

Heart failure

T2D increases both atherosclerotic and non-ischaemic heart-failure risk. SGLT2 trials in people with and without diabetes shifted HF from a complication treated downstream to a preventable organ outcome (McMurray 2019, PMID 31535829; Packer 2020, PMID 32865377).

MASLD overlap

Steatotic liver disease and T2D share insulin resistance and ectopic-fat biology. Fibrosis, not steatosis alone, drives liver prognosis; routine liver enzymes can be normal despite advanced disease. The relationship is bidirectional and also marks higher cardiovascular risk (Driessen 2025, PMID 38147315).

Multimorbidity and treatment burden

Complications cluster. CKD changes drug dosing and HbA1c interpretation; visual loss impairs medication administration; neuropathy and heart failure limit exercise; depression and distress impair self-management. Single-organ guidelines can create conflicting regimens.

Surveillance matrix

Domain Baseline/interval principle Escalate when
Kidney UACR and eGFR at least annually; more often with CKD Rapid decline, active sediment, resistant pressure
Retina At diagnosis and finding/risk-dependent follow-up Sudden symptoms or advanced changes
Feet At least annual comprehensive exam; more often high risk Ulcer, infection, ischaemia, Charcot suspicion
Neuropathy Symptom/exam review Motor, asymmetry, rapid progression, autonomic instability
Cardiovascular Ongoing risk-factor assessment Symptoms or major risk transition
Liver Fibrosis-risk pathway in high-risk T2D High/indeterminate noninvasive score
Mental health Clinical/distress screening Self-harm risk, severe depression, eating disorder

Atypical features suggesting another diagnosis

Finding Alternative concern
Haematuria/active urine sediment Non-diabetic kidney disease
Rapid eGFR loss without albuminuria context Vascular, obstructive or inflammatory disease
Asymmetric motor neuropathy Entrapment, radiculopathy, inflammatory/vascular neuropathy
Painful red eye Glaucoma/uveitis rather than routine retinopathy
Acute unilateral hot swollen foot Charcot, infection or thrombosis
Severe transaminase rise Acute liver disease beyond MASLD

Risk-factor interaction

Interaction Consequence
CKD + hypoglycaemia-prone drugs Longer/severe low glucose
Neuropathy + PAD Ulcer without warning pain and poor healing
Retinopathy + rapid HbA1c fall Early worsening risk
HF + pioglitazone Fluid-retention hazard
Autonomic neuropathy + intensive therapy Impaired low-glucose warning
Depression + cost burden Treatment interruption and distress

Outcome ascertainment limitations

Claims-coded complications may reflect access and coding rather than biological incidence. Albuminuria endpoints are more frequent than kidney failure; retinopathy grading systems differ; amputation level and recurrence may be inconsistently counted. Tables in statistics preserve population and method rather than combining unlike estimates.

Prevention hierarchy

  1. Detect risk and existing disease.
  2. Control smoking, blood pressure, lipids and glycaemia safely.
  3. Add organ-protective therapy for absolute-risk phenotype.
  4. Treat early lesions (retina, foot, kidney) before irreversible loss.
  5. Reduce treatment burden and preserve access so prevention persists.

Cross-domain evidence crosswalk

These adjacent studies constrain interpretation of this page and make explicit where its conclusions depend on prevention, organ-outcome, remission, burden or implementation evidence.

Verified evidence anchor Connection
(GBD 2023, PMID 37356446) GBD 2021 Diabetes Collaborators. Global, regional, and national burden of diabetes from 1990 to 2021, with projections of prevalence to 2050. Lancet. 2023;402:203-234
(Zhang 2024, PMID 39151887) Zhang H, et al. Global burden of metabolic diseases, 1990-2021. Metabolism. 2024;160:155999
(Ma 2025, PMID 40060381) Ma X, et al. Global burden of chronic kidney disease due to diabetes mellitus, 1990-2021, and projections to 2050. Front Endocrinol. 2025;16:1513008
(TODAY 2021, PMID 34320286) TODAY Study Group. Long-Term Complications in Youth-Onset Type 2 Diabetes. N Engl J Med. 2021
(TODAY 2012, PMID 22540912) TODAY Study Group. A clinical trial to maintain glycemic control in youth with type 2 diabetes. N Engl J Med. 2012
(ADA 2026, PMID 41358899) ADA Professional Practice Committee. Cardiovascular Disease and Risk Management: Standards of Care-2026. Diabetes Care. 2026
(American 2026, PMID 41358900) American Diabetes Association Professional Practice Committee. Pharmacologic Approaches: Standards of Care-2026. Diabetes Care. 2026
(ACCORD 2008, PMID 18539917) ACCORD Study Group. Effects of intensive glucose lowering in type 2 diabetes. N Engl J Med. 2008
(Holman 2008, PMID 18784090) Holman RR, et al. 10-year follow-up of intensive glucose control. N Engl J Med. 2008;359:1577-1589

Complications share drivers but not identical treatment responses

Steno-2 tested simultaneous modification rather than serial single-risk-factor care. In 160 adults with microalbuminuria, intensive multifactorial treatment reduced cardiovascular disease (HR 0.47, 95% CI 0.24–0.73), nephropathy (0.39, 0.17–0.87), retinopathy (0.42, 0.21–0.86) and autonomic neuropathy (0.37, 0.18–0.79) over 7.8 years (Gaede 2003, PMID 12556541). At 13.3 years, death HR was 0.54 (0.32–0.89), and at 21.2 years median survival was 7.9 years longer (Gaede 2008, PMID 18256393; Gæde 2016, PMID 27531506). The package cannot identify which component caused which benefit.

By contrast, ACCORD Eye separated interventions. Retinopathy progression was 7.3% versus 10.4% with intensive glycaemia (OR 0.67, 95% CI 0.51–0.87), 6.5% versus 10.2% with fenofibrate/simvastatin versus simvastatin (OR 0.60, 0.42–0.87), and 10.4% versus 8.8% with intensive versus standard BP targets (OR 1.23, 0.84–1.79) (Chew 2010, PMID 20587587). Prior intensive glycaemia retained a four-year post-trial retinopathy effect, while the fenofibrate effect did not persist (ACCORDION Eye 2016, PMID 27289122).

High-burden domains often missed by glucose-centric follow-up

Domain Quantified burden Interpretation
MASLD Pooled prevalence in T2D 65.33% (95% CI 62.35%–68.18%); biopsy series: MASH 66.44%, advanced fibrosis 15.49% Referral-enriched biopsy estimates are not population prevalence (Younossi 2024, PMID 38521116)
Charcot foot Five-year mortality 24.5% (17.2%–32.6%); any amputation 15%, major 9% Very high heterogeneity; Charcot cohorts differ in ulceration/infection (Yammine 2022, PMID 36028441)
Healed foot ulcer Recurrence 6.2%–41.4% across nine studies; validation-model pooled AUC 0.83 (0.79–0.88) Only five models externally validated; calibration often incomplete (Sun 2024, PMID 39004600)
Remission Look AHEAD remission associated with CKD HR 0.67 (0.52–0.87) and CVD HR 0.60 (0.47–0.79) Post-randomisation association, not licence to stop surveillance (Gregg 2024, PMID 38233592)

Social risk modifies complication trajectories

In a South Korean cohort, complication hospitalisation increased from 25.4% in the least-deprived quintile to 37.6% in the most deprived; all-cause death increased from 5.7% to 13.1% (Choi 2020, PMID 32611580). This gradient may reflect access, treatment continuity, environment and comorbidity rather than biology. Surveillance tables therefore need an implementation column: an annual recommendation has no effect if retinal imaging, UACR testing, footwear or specialist review are inaccessible.

Controversies

Question Evidence on one side Evidence on the other
Should every person with T2D undergo liver-fibrosis screening? High pooled MASLD and fibrosis prevalence (Younossi 2024, PMID 38521116) Biopsy selection and false positives can create referrals without outcome benefit
Does remission remove complication risk? Lower observed CKD/CVD incidence (Gregg 2024, PMID 38233592) Prior exposure, selection and relapse remain; no de-surveillance trial
Is tighter BP always microvascular protection? BP lowering reduces vascular risk in appropriate populations ACCORD Eye found no retinopathy advantage for <120 vs <140 mmHg
Can foot recurrence scores guide care? Discrimination often acceptable Calibration, transportability and intervention utility remain insufficient

Open questions

  • Which combination sequence best prevents simultaneous kidney, HF and atherosclerotic outcomes?
  • Can retinal imaging, UACR trajectories and autonomic measures identify a shared microvascular endotype?
  • What surveillance interval is optimal after remission, given persistent legacy risk? (Riddle 2021, PMID 34462270)
  • How should MASLD fibrosis screening be integrated without overdiagnosis?

References

  1. Rawshani A, et al. Mortality and Cardiovascular Disease in Type 1 and Type 2 Diabetes. N Engl J Med. 2017. PMID 28402770
  2. Nanayakkara N, et al. Age at T2D diagnosis and vascular complications. Diabetologia. 2021;64:275-287. PMID 33313987
  3. Adler AI, et al. UKPDS 91: 24-year post-trial monitoring. Lancet. 2024;404:145-155. PMID 38772405
  4. Zinman B, et al. Empagliflozin Cardiovascular Outcomes. N Engl J Med. 2015. PMID 26378978
  5. Kristensen SL, et al. GLP-1RA cardiovascular, mortality, and kidney outcomes. Lancet Diabetes Endocrinol. 2019;7:776-785. PMID 31422062
  6. Palmer SC, et al. SGLT2 inhibitors and GLP-1RA network meta-analysis. BMJ. 2021. PMID 33441402
  7. Perkovic V, et al. Canagliflozin and Renal Outcomes. N Engl J Med. 2019. PMID 30990260
  8. Perkovic V, et al. Semaglutide on CKD in T2D. N Engl J Med. 2024. PMID 38785209
  9. Cai K, et al. Retinopathy in newly diagnosed T2D. Diabetes Metab Res Rev. 2023;39:e3586. PMID 36286346
  10. Teo ZL, et al. Global prevalence of diabetic retinopathy. Ophthalmology. 2021;128:1580-1591. PMID 33940045
  11. Marso SP, et al. Semaglutide Cardiovascular Outcomes. N Engl J Med. 2016. PMID 27633186
  12. ADA Professional Practice Committee. Retinopathy, Neuropathy, and Foot Care-2026. Diabetes Care. 2026. PMID 41358886
  13. McMurray JJV, et al. Dapagliflozin in HFrEF. N Engl J Med. 2019. PMID 31535829
  14. Packer M, et al. Empagliflozin in HFrEF. N Engl J Med. 2020. PMID 32865377
  15. Driessen S, et al. Metabolic dysfunction-associated steatotic liver disease and the heart. Hepatology. 2025;82:487-503. PMID 38147315
  16. Riddle MC, et al. Definition and Interpretation of Remission. Diabetes Care. 2021. PMID 34462270
  17. GBD 2021 Diabetes Collaborators. Global, regional, and national burden of diabetes from 1990 to 2021, with projections of prevalence to 2050. Lancet. 2023;402:203-234. PMID 37356446
  18. Zhang H, et al. Global burden of metabolic diseases, 1990-2021. Metabolism. 2024;160:155999. PMID 39151887
  19. Ma X, et al. Global burden of chronic kidney disease due to diabetes mellitus, 1990-2021, and projections to 2050. Front Endocrinol. 2025;16:1513008. PMID 40060381
  20. TODAY Study Group. Long-Term Complications in Youth-Onset Type 2 Diabetes. N Engl J Med. 2021. PMID 34320286
  21. TODAY Study Group. A clinical trial to maintain glycemic control in youth with type 2 diabetes. N Engl J Med. 2012. PMID 22540912
  22. ADA Professional Practice Committee. Cardiovascular Disease and Risk Management: Standards of Care-2026. Diabetes Care. 2026. PMID 41358899
  23. American Diabetes Association Professional Practice Committee. Pharmacologic Approaches: Standards of Care-2026. Diabetes Care. 2026. PMID 41358900
  24. ACCORD Study Group. Effects of intensive glucose lowering in type 2 diabetes. N Engl J Med. 2008. PMID 18539917
  25. Holman RR, et al. 10-year follow-up of intensive glucose control. N Engl J Med. 2008;359:1577-1589. PMID 18784090
  26. Gaede P, et al. Multifactorial intervention and cardiovascular disease. N Engl J Med. 2003;348:383-393. PMID 12556541
  27. Gaede P, et al. Multifactorial intervention and mortality. N Engl J Med. 2008;358:580-591. PMID 18256393
  28. Gæde P, et al. Years of life gained: 21-year Steno-2 follow-up. Diabetologia. 2016;59:2298-2307. PMID 27531506
  29. Chew EY, et al. Medical therapies and retinopathy progression. N Engl J Med. 2010;363:233-244. PMID 20587587
  30. ACCORDION Eye Study Group. Persistent Effects of Intensive Glycemic Control on Retinopathy. Diabetes Care. 2016;39:1089-1100. PMID 27289122
  31. Younossi ZM, et al. Global Epidemiology of MASLD and MASH Among Patients With T2D. Clin Gastroenterol Hepatol. 2024;22:1999-2010.e8. PMID 38521116
  32. Yammine K, et al. Amputation and mortality associated with diabetic Charcot foot. Foot Ankle Surg. 2022;28:1170-1176. PMID 36028441
  33. Sun Y, et al. Predictors of recurrence after diabetic foot-ulcer healing. Int J Nurs Stud. 2024;159:104870. PMID 39004600
  34. Choi DW, et al. Socioeconomic deprivation and diabetes-complication outcomes. BMJ Open Diabetes Res Care. 2020;8. PMID 32611580
  35. Gregg EW, et al. Remission and long-term CKD/CVD outcomes in Look AHEAD. Diabetologia. 2024;67:459-469. PMID 38233592