What do GLP-1s do to your kidneys? Today we cover the benefits, harms, and a verdict, built from a full literature review. Dr. Clete Barrick MD, board-certified in internal medicine and obesity medicine, continues Season 2 of Straight Shot: every organ, one episode at a time. This one is the kidney. In this episode: - FLOW, the only trial in this class built to test the kidney: semaglutide cut kidney failure, 50% filtration loss, or kidney and heart death 24% in 3,533 people with type 2 diabetes and kidney disease, and it stopped early - The two numbers that run the episode: estimated glomerular filtration rate (eGFR), and the urine albumin-to-creatinine ratio (UACR), the earliest signal kidney disease gives and the one most patients have never had checked - A class effect, not a semaglutide effect: kidney events down 18% across 11 placebo-controlled trials and 85,000 participants, with kidney failure itself the least secure piece - Already on Jardiance or Farxiga? The FLOW subgroup everyone quotes has 79 events and cannot answer the question either way. You add, you don't swap - Obesity without diabetes: SELECT cut the kidney composite 22%, and SMART dropped urine albumin 52% in 24 weeks in nondiabetic kidney disease - Mostly not the weight loss: blood sugar explained about a quarter of the benefit and weight almost nothing, and below an eGFR of 60 the blood sugar piece disappeared - Semaglutide or tirzepatide: SURPASS-CVOT cut major kidney events 23% against dulaglutide, a drug that protects kidneys in its own right, but tirzepatide has no placebo-controlled kidney trial and no kidney indication - The harm column is dehydration, not toxicity: no excess acute kidney injury across 12 trials and 36,000 participants, the sick-day rule, and why the American Diabetes Association (the ADA) says a creatinine bump under 30% is not a reason to stop - Reading your own labs during rapid weight loss: creatinine tracks muscle, cystatin C tracks fat, and in one trial's patients creatinine overshot measured filtration by 15 points - Dialysis and transplant: 165 people stayed on semaglutide after starting dialysis with no safety signal, and in 18,016 transplant recipients GLP-1 use tracked with half the graft loss, with one caveat about the eyes - Retatrutide: urine albumin falls 28 to 37% in Phase 2 trials, the eGFR rises, and the trial that could tell protection from hyperfiltration finished last October and has not published The GLP-1 Bible, preorder now: barrickhealth.com/glp1-bible Free first visit with Dr. Barrick: barrickhealth.com Chapters 0:00 One trial built for the kidney, and one number that lies 1:05 Why kidney disease is silent, and the new fourth pillar 3:31 The two numbers: eGFR and urine albumin 5:22 FLOW: the only kidney outcome trial in the class 7:46 Already on an SGLT2 inhibitor: add or swap? 8:48 Semaglutide, or the whole class? 10:19 Obesity without diabetes: SELECT and SMART 13:05 Semaglutide or tirzepatide for the kidney 15:04 The harm column: dehydration, not toxicity 18:07 Dialysis, the transplant list, and after transplant 19:54 Reading your kidney labs while losing weight 22:30 Retatrutide: why a rising eGFR proves nothing 24:53 What I tell my patients: the kidney verdict Sources (author, year, PubMed identifier) Kidney outcome trial: Perkovic 2024, 38785209; Tuttle 2026, 41706532; Tuttle 2026, 42233552. Class effect: Badve 2025, 39608381; Sasaki 2026, 40982219; Lee 2025, 40156846. Individual agents: Mann 2017, 28854085; Gerstein 2019, 31189509; Gerstein 2021, 34215025; Bethel 2020, 31757838; Muskiet 2018, 30292589; McGuire 2025, 40162642. Layering with SGLT2 inhibitors: Mann 2024, 38914124; Neuen 2024, 39210781; Jansz 2026, 42109572. Without diabetes: Colhoun 2024, 38796653; Apperloo 2025, 39455729; Heerspink 2026, 42308057. Mechanism: Mann 2021, 34009708; Alicic 2021, 33219281. Tirzepatide: Zoungas 2026, 42114520; Nicholls 2025, 41406444; Heerspink 2025, 40512543; Heerspink 2022, 36152639; Apperloo 2025, 39746157. Safety, dosing, the early creatinine rise: Packer 2025, 40162940; Feghali 2024, 39298632; Marbury 2017, 28349386; Urva 2021, 33778934; Idorn 2016, 26283739. Measuring filtration during weight loss: Yahya 2026, 42397155; Heerspink 2026, 41160422. Dialysis and transplant: Klein 2026, 41893299; Wade 2025, 41075262; Orandi 2025, 40056927; Kanbay 2026, 42017027. Retatrutide: Heerspink 2025, 40630318; ClinicalTrials.gov NCT06383390. Guidelines and label: Ndumele 2026, 42263157; ADA Standards of Care 2026, 41358881; KDIGO 2026 guideline, public review draft; the FDA, Ozempic kidney indication, January 28 2025. Educational content, not medical advice. Talk with your clinician before changing any medication. #GLP1 #Ozempic #Wegovy #KidneyHealth #StraightShot