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Type 2 diabetes — red flags and safety concerns

TL;DR — Altered mental state, profound dehydration, vomiting, abdominal pain, deep breathing, severe hypoglycaemia, spreading foot infection and sudden visual change require urgent evaluation. SGLT2-associated DKA may occur with glucose below classic DKA thresholds, especially during fasting, surgery, acute illness or insulin reduction (Dutta 2022, PMID 35495849). Sulfonylureas and insulin cause the most clinically important treatment-related hypoglycaemia; risk rises with CKD, frailty, missed meals and dosing error. Rapid HbA1c improvement can transiently worsen advanced retinopathy, while GLP-1 therapy commonly causes gastrointestinal symptoms that can become dangerous when intake and hydration fail.

Acute metabolic emergencies

Syndrome Red flags Key pitfall
Hyperosmolar hyperglycaemic state Extreme thirst/polyuria, dehydration, confusion, weakness May lack prominent ketosis
DKA Nausea, vomiting, abdominal pain, deep breathing, ketones, acidosis T2D does not exclude DKA
Euglycaemic DKA Same symptoms with modest glucose on SGLT2 inhibitor Normal-looking glucose delays diagnosis
Severe hypoglycaemia Confusion, seizure, unconsciousness, need for assistance Symptoms may be blunted in older adults

SGLT2 sick-day hazards

Risk factors include acute infection, fasting, surgery, dehydration, ketogenic diets, excess alcohol, insulin deficiency and abrupt insulin reduction (Dutta 2022, PMID 35495849).

Situation Safety principle
Planned surgery/prolonged fasting Withhold in advance per current protocol
Acute vomiting/poor intake Stop temporarily; hydrate and assess ketones
DKA symptoms Check blood ketones/acid-base status regardless of glucose
Restart After recovery, normal intake and risk review

Hypoglycaemia

Risk amplifier Mechanism
Insulin/sulfonylurea Glucose-independent insulin action/secretion
CKD Reduced clearance and impaired gluconeogenesis
Missed meals/alcohol Reduced substrate and hepatic output
Frailty/cognitive impairment Dosing and symptom-response difficulty
Prior severe event Strong recurrence marker
Tight target Smaller safety margin

ACCORD shows that intensive glycaemic strategies can cause net harm in high-risk populations (ACCORD 2008, PMID 18539917). Deintensification is evidence-aligned when treatment hazard exceeds long-horizon benefit.

Foot emergencies

Finding Concern
Spreading erythema, systemic illness Severe infection/sepsis
Necrosis, rest pain, absent pulses Critical limb ischaemia
Warm swollen foot with little pain Acute Charcot neuroarthropathy
Deep ulcer/probe to bone Osteomyelitis
Gas, crepitus, rapidly progressive pain Necrotising infection

Neuropathy can suppress pain, so absence of pain does not reassure (ADA 2026, PMID 41358886).

Eye red flags

Sudden visual loss, new field defect, flashes/floaters with curtain-like loss, painful red eye or rapid change after major glycaemic improvement warrants urgent eye assessment. SUSTAIN-6 identified a retinopathy-complication signal during rapid semaglutide-associated HbA1c improvement (Marso 2016, PMID 27633186).

GLP-1/incretin safety

Issue Escalation trigger
Vomiting/diarrhoea Dehydration, AKI risk, inability to retain fluids
Persistent severe abdominal pain Pancreatitis/gallbladder assessment
Severe constipation/distension Obstruction/ileus assessment
Delayed gastric emptying Anaesthesia/procedure planning
Hypoglycaemia Review concomitant insulin/sulfonylurea
Rapid visual change Retinopathy assessment

Insulin-deficiency clues in “T2D”

Unexpected weight loss, ketosis, rapid oral-drug failure, low C-peptide or personal/family autoimmune history should trigger reconsideration of classification. Misclassified type 1/LADA treated without adequate insulin can progress to DKA.

Medication-specific monitoring

Drug Important concern
Metformin Accumulation risk in severe acute renal/hypoxic illness; B12 with long use
Sulfonylurea Prolonged hypoglycaemia, especially CKD/older age
Pioglitazone Fluid retention/HF, fracture risk
Insulin Hypoglycaemia, dosing error, storage/access interruption
SGLT2 inhibitor DKA, genital infection, volume depletion
GLP-1RA/tirzepatide GI intolerance, gallbladder, procedure planning

Hyperosmolar state versus DKA

Feature HHS tendency DKA tendency
Glucose Often extreme Variable; may be modest with SGLT2
Ketones/acidosis Minimal/mild Central feature
Dehydration Profound Common
Mental status Frequently altered Variable
Evolution Often days Often faster
Overlap Common Common

The syndromes overlap; classification should not delay fluid, electrolyte, insulin and precipitant management in an acute-care setting.

Category Examples
Infection Urinary, respiratory, skin/foot, sepsis
Vascular MI, stroke, mesenteric/limb ischaemia
Medication Steroid, missed insulin, SGLT2 exposure
Access Insulin unaffordability, supply interruption
Gastrointestinal Vomiting, pancreatitis, starvation
Endocrine Thyrotoxicosis or other acute stressor

When ordinary symptoms become urgent

Symptom Escalating combination
Nausea Persistent vomiting + SGLT2/ketones
Thirst Confusion + profound polyuria/dehydration
Foot wound Erythema, fever, ischaemia or deep structure
Low glucose Impaired cognition or need for assistance
Abdominal pain Acidosis, peritonism or persistent severe pain
Visual symptom Sudden loss/field defect/flashes and curtain

Safety at transitions

Transition Preventive control
Hospital discharge Reconcile insulin, renal function and stopped drugs
After major weight loss Reassess hypoglycaemia-prone doses
Surgery/procedure SGLT2 withholding and GLP-1 gastric-emptying plan
New CKD Dose and HbA1c reliability review
Remission Continue surveillance; define restart threshold
Supply shortage Safe substitution plan, not abrupt interruption

Exploitation and misinformation

Claims of permanent “cure,” unregulated supplements, extreme carbohydrate restriction during SGLT2 therapy and advice to stop prescribed medicine can cause harm. Remission is evidence-based but conditional and relapse-prone (Riddle 2021, PMID 34462270; Lean 2024, PMID 38423026).

Research safety metrics

Trials should report severe hypoglycaemia, DKA with glucose distribution, dehydration/AKI, foot events, retinopathy progression, treatment discontinuation and serious GI events. Aggregate “serious adverse event” totals can conceal mechanism-specific harm.

EMPA-REG established the large benefit context for accepting rare SGLT2 harms, while ADA/EASD and the current ADA pharmacology standard translate that balance into selection and monitoring (Zinman 2015, PMID 26378978; Davies 2022, PMID 36148880; ADA 2026, PMID 41358900).

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
(Neal 2017, PMID 28605608) Neal B, et al. Canagliflozin and Cardiovascular and Renal Events in Type 2 Diabetes. N Engl J Med. 2017
(Wiviott 2019, PMID 30415602) Wiviott SD, et al. Dapagliflozin and Cardiovascular Outcomes in Type 2 Diabetes. N Engl J Med. 2019
(Perkovic 2019, PMID 30990260) Perkovic V, et al. Canagliflozin Renal Outcomes. N Engl J Med. 2019
(Heerspink 2020, PMID 32970396) Heerspink HJL, et al. Dapagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2020
(EMPA-KIDNEY 2023, PMID 36331190) EMPA-KIDNEY Collaborative Group. Empagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2023
(Marso 2016, PMID 27295427) Marso SP, et al. Liraglutide Cardiovascular Outcomes. N Engl J Med. 2016
(Frías 2021, PMID 34170647) Frías JP, et al. Tirzepatide versus Semaglutide. N Engl J Med. 2021
(Jastreboff 2022, PMID 35658024) Jastreboff AM, et al. Tirzepatide for Obesity. N Engl J Med. 2022
(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
(Rawshani 2017, PMID 28402770) Rawshani A, et al. Mortality and Cardiovascular Disease in Type 1 and Type 2 Diabetes. N Engl J Med. 2017
(ADA 2026, PMID 41358899) ADA Professional Practice Committee. Cardiovascular Disease and Risk Management: Standards of Care-2026. Diabetes Care. 2026
(ADA 2026, PMID 41358893) ADA Professional Practice Committee. Diagnosis and Classification of Diabetes: Standards of Care-2026. Diabetes Care. 2026
(Palmer 2021, PMID 33441402) Palmer SC, et al. SGLT2 inhibitors and GLP-1RA network meta-analysis. BMJ. 2021
(Perkovic 2024, PMID 38785209) Perkovic V, et al. Semaglutide on CKD. N Engl J Med. 2024
(Look AHEAD 2022, PMID 35312758) Look AHEAD Research Group. Effects of Intensive Lifestyle Intervention on All-Cause Mortality. Diabetes Care. 2022

Hyperglycaemic crisis phenotypes overlap

The 2024 ADA/EASD/JBDS/AACE/DTS consensus updated adult DKA and HHS diagnosis, treatment and prevention after systematic evidence review (Umpierrez 2024, PMID 39052901). HHS classically combines glucose >600 mg/dL and effective osmolality >320 mOsm/kg without major ketoacidosis, but mixed DKA–HHS is common and older thresholds should not substitute for the current consensus algorithm (Pasquel 2014, PMID 25342831).

Crisis feature DKA-predominant HHS-predominant Mixed-risk implication
Ketones/acidosis Central Absent or mild Significant ketones/acidosis plus hyperosmolality
Glucose Often high; can be <200–250 mg/dL with SGLT2 use Usually extreme Glucose alone cannot classify severity
Osmolality/dehydration Variable Marked Neurological and thrombotic risk rises
Typical context Insulin deficiency, infection, omission, SGLT2/fasting Older T2D, infection, dehydration, impaired access Treat overlapping physiology, not label alone

In 1,211 confirmed crisis admissions, 38% were isolated DKA, 35% HHS and 27% combined. Mixed DKA–HHS carried adjusted in-hospital mortality OR 2.7 (95% CI 1.4–4.9) versus isolated crisis; treatment-associated glucose <40 mg/dL had OR 4.8 (1.4–16.8) and potassium ≤2.5 mEq/L OR 4.9 (1.3–18.8) (Pasquel 2020, PMID 31704689). Correction itself can therefore create lethal hypoglycaemia, hypokalaemia and rapid-osmolality-shift hazards.

US HHS admissions increased from 2008 to 2018 while inpatient mortality declined from 1.44% to 0.77%; coding-based trends do not capture post-discharge death or diagnostic overlap (Shaka 2022, PMID 35122906). Older reviews reported 10%–20% mortality, demonstrating that era, case definition and setting radically alter estimates (Fayfman 2017, PMID 28372715; Pasquel 2014, PMID 25342831).

Severe hypoglycaemia: causal hazard and vulnerability marker

In ADVANCE, 231/11,140 participants had severe hypoglycaemia. It was associated with macrovascular events HR 2.88 (95% CI 2.01–4.12), microvascular events HR 1.81 (1.19–2.74), cardiovascular death HR 2.68 (1.72–4.19) and all-cause death HR 2.69 (1.97–3.67) (Zoungas 2010, PMID 20925543). Similar associations with nonvascular outcomes and no dose-response across repeated episodes support two simultaneous interpretations: hypoglycaemia may contribute to harm and may mark frailty/comorbidity.

Diabetes distress intersects with safety: any distress was associated with severe hypoglycaemia OR 2.3 (95% CI 1.3–3.9), while distress plus depressive symptoms had OR 4.3 (2.5–7.3) in a 2,040-person cohort (Al Sayah 2019, PMID 30578165). Event review should therefore include cognition, food access, regimen complexity, fear, mood, alcohol, kidney function and support—not only dose adjustment.

Drug-specific controversy: rare events and denominator problems

Signal Quantified evidence Safety interpretation
Tirzepatide pancreatitis Nine-trial RR 1.46 (95% CI 0.59–3.61), not significant Wide interval; rare-event uncertainty remains (Zeng 2023, PMID 37908750)
Tirzepatide gallbladder/biliary composite RR 1.97 (1.14–3.42) vs placebo/basal insulin Composite significant; individual events not consistently so
GLP-1RA digestive-event meta-analysis Pancreatitis RR 1.48 (1.02–2.15), acute cholecystitis RR 1.52 (1.08–2.15) Multiple 91-outcome testing and rare events require cautious interpretation (Wang 2022, PMID 36042668)
Updated GLP-1RA RCT synthesis 62 trials; pancreatitis RR 1.44 (1.09–1.89), attenuating to nonsignificance in background-medication strata Mean follow-up 43.5 weeks; double-zero studies were excluded (Wen 2025, PMID 40988099)
Tirzepatide dose analysis 19 RCTs; 0.22% pancreatitis; 15 vs 5 mg RR 0.70 (0.27–1.82) No detected dose response, with wide confidence intervals (Benny 2026, PMID 41927408)
Updated tirzepatide biliary synthesis 12 RCTs; gallbladder/biliary disease RR 1.52 (1.17–1.98), cholelithiasis RR 1.67 (1.14–2.44) Supports a biliary signal without a detected dose response (Gong 2025, PMID 39569606)
SGLT2 euglycaemic DKA Case-based synthesis confirms glucose can remain below usual DKA expectations Case reports establish phenotype, not incidence; illness/fasting/insulin deficiency concentrate risk

Conflicting pooled pancreatitis estimates should be shown, not reconciled by adjective. Different molecule sets, comparators, event adjudication and multiplicity can shift a rare-event estimate across significance. Acute persistent abdominal pain, vomiting, dehydration or ketosis still warrants assessment regardless of population-level uncertainty.

Open questions

  • Which sick-day intervention best reduces SGLT2 DKA without unnecessary discontinuation?
  • Can EHR systems identify insulin/sulfonylurea overtreatment before severe hypoglycaemia?
  • What titration strategy minimises early retinopathy worsening during large HbA1c reductions?
  • Which foot triage model reduces amputation delays across low-resource settings?

References

  1. Dutta S, et al. Euglycemic diabetic ketoacidosis associated with SGLT2 inhibitors. J Family Med Prim Care. 2022;11:927-940. PMID 35495849
  2. ACCORD Study Group. Effects of intensive glucose lowering in T2D. N Engl J Med. 2008. PMID 18539917
  3. ADA Professional Practice Committee. Retinopathy, Neuropathy, and Foot Care-2026. Diabetes Care. 2026. PMID 41358886
  4. Marso SP, et al. Semaglutide and Cardiovascular Outcomes. N Engl J Med. 2016. PMID 27633186
  5. Zinman B, et al. Empagliflozin Cardiovascular Outcomes. N Engl J Med. 2015. PMID 26378978
  6. Davies MJ, et al. Management of Hyperglycemia in Type 2 Diabetes, 2022. Diabetes Care. 2022. PMID 36148880
  7. American Diabetes Association Professional Practice Committee. Pharmacologic Approaches-2026. Diabetes Care. 2026. PMID 41358900
  8. Riddle MC, et al. Definition and Interpretation of Remission. Diabetes Care. 2021. PMID 34462270
  9. Lean MEJ, et al. Five-year follow-up of DiRECT. Lancet Diabetes Endocrinol. 2024. PMID 38423026
  10. Neal B, et al. Canagliflozin and Cardiovascular and Renal Events in Type 2 Diabetes. N Engl J Med. 2017. PMID 28605608
  11. Wiviott SD, et al. Dapagliflozin and Cardiovascular Outcomes in Type 2 Diabetes. N Engl J Med. 2019. PMID 30415602
  12. Perkovic V, et al. Canagliflozin Renal Outcomes. N Engl J Med. 2019. PMID 30990260
  13. Heerspink HJL, et al. Dapagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2020. PMID 32970396
  14. EMPA-KIDNEY Collaborative Group. Empagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2023;388:117-127. PMID 36331190
  15. Marso SP, et al. Liraglutide Cardiovascular Outcomes. N Engl J Med. 2016. PMID 27295427
  16. Frías JP, et al. Tirzepatide versus Semaglutide. N Engl J Med. 2021. PMID 34170647
  17. Jastreboff AM, et al. Tirzepatide for Obesity. N Engl J Med. 2022. PMID 35658024
  18. TODAY Study Group. Long-Term Complications in Youth-Onset Type 2 Diabetes. N Engl J Med. 2021. PMID 34320286
  19. TODAY Study Group. A clinical trial to maintain glycemic control in youth with type 2 diabetes. N Engl J Med. 2012. PMID 22540912
  20. Rawshani A, et al. Mortality and Cardiovascular Disease in Type 1 and Type 2 Diabetes. N Engl J Med. 2017. PMID 28402770
  21. ADA Professional Practice Committee. Cardiovascular Disease and Risk Management: Standards of Care-2026. Diabetes Care. 2026. PMID 41358899
  22. ADA Professional Practice Committee. Diagnosis and Classification of Diabetes: Standards of Care-2026. Diabetes Care. 2026. PMID 41358893
  23. Palmer SC, et al. SGLT2 inhibitors and GLP-1RA network meta-analysis. BMJ. 2021. PMID 33441402
  24. Perkovic V, et al. Semaglutide on CKD. N Engl J Med. 2024. PMID 38785209
  25. Look AHEAD Research Group. Effects of Intensive Lifestyle Intervention on All-Cause Mortality. Diabetes Care. 2022. PMID 35312758
  26. Umpierrez GE, et al. Hyperglycemic Crises in Adults With Diabetes: A Consensus Report. Diabetes Care. 2024;47:1257-1275. PMID 39052901
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