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Draft: not yet reviewed by a clinician

Use this page to prepare questions for your care team. It does not replace their advice. Your own targets and doses come from your nephrologist, diabetes team and renal dietitian.

How kidney disease changes type 1 diabetes

No doses on this page

This handbook never gives insulin or medicine doses and never tells you to change one. Your prescriber sets every dose and every change, and writes down when to pause a medicine and when to restart it. A low blood glucose is always treated straight away: see Treating a low and Get help now.

In short

Your kidneys help to control glucose. They clear insulin from the blood and they make some glucose of their own. As kidney function falls, insulin stays in the body longer and the kidneys make less glucose, so lows become more common and insulin needs often go down (ADA–KDIGO 2022). The warning signs of a low can also fade. But with type 1 diabetes you always need insulin: your team lowers or reshapes the plan, it never stops it. Treat every low at once, have a written sick-day plan, and bring your glucose data to every visit.

Why kidney disease changes your glucose

  • Insulin lasts longer. The kidneys remove a large share of injected insulin. With less kidney function, each dose keeps working for longer. For type 1 diabetes, the ADA–KDIGO report says insulin doses "may need to be decreased" in advanced kidney disease because the kidneys clear less insulin (ADA–KDIGO 2022).
  • The kidneys make less glucose. Healthy kidneys supply about a fifth of the body's glucose, partly by making new glucose. Kidney disease cuts the glucose they make, which raises the risk of lows (Pecoits-Filho 2016).
  • Eating less. Poor appetite and a strict kidney diet both mean less glucose coming in. A restricted kidney diet also cuts the glucose the liver makes (Pecoits-Filho 2016).
  • Fainter warning signs. Nerve damage from long-standing diabetes can blunt the shaking, sweating and racing heart that warn of a low. In one series, about two in three people with advanced kidney disease had this kind of nerve damage (Pecoits-Filho 2016).
  • The result: lows are about twice as common in people with kidney disease (JBDS–Renal Association). The ADA lists kidney disease as a risk factor for lows and asks for a check of low awareness at least once a year (ADA 2026 §6, recommendation 6.11).

Your numbers

Starting points, not your prescription

These numbers are typical starting points from guidelines. Your nephrologist, diabetes team and renal dietitian set your own numbers from your blood tests, urine output and medicines, and change them as your labs change. If your lab report or your team says something different, they win.

What Typical goal or level Source
Level 1 low below 70 mg/dL ADA 2026 §6
Level 2 low below 54 mg/dL ADA 2026 §6
Level 3 low any low where you need someone's help ADA 2026 §6
CGM time in range (70–180 mg/dL) more than 70 % of the day (more than 50 % if you are older or at high risk of lows) ADA 2026 §6; time-in-range consensus
CGM time below 70 mg/dL under 4 % (under 1 % if you are older or at high risk of lows) ADA 2026 §6
CGM time below 54 mg/dL under 1 % ADA 2026 §6
A1c goal (not on dialysis) set for you, somewhere between under 6.5 % and under 8.0 % KDIGO 2022, recommendation 2.2.1
What Typical goal or level Source
Level 1 low below 3.9 mmol/L ADA 2026 §6
Level 2 low below 3.0 mmol/L ADA 2026 §6
Level 3 low any low where you need someone's help ADA 2026 §6
CGM time in range (3.9–10.0 mmol/L) more than 70 % of the day (more than 50 % if you are older or at high risk of lows) ADA 2026 §6; time-in-range consensus
CGM time below 3.9 mmol/L under 4 % (under 1 % if you are older or at high risk of lows) ADA 2026 §6
CGM time below 3.0 mmol/L under 1 % ADA 2026 §6
A1c goal (not on dialysis) set for you, somewhere between under 48 and under 64 mmol/mol KDIGO 2022, recommendation 2.2.1

A1c becomes less reliable at stages G4–G5 and on dialysis, so CGM data matter more (KDIGO 2022, practice point 2.1.2). See A1c and CGM reports.

What changes along the way

Where you are What often happens What helps
Stages G1–G3a Glucose and blood pressure control protect the kidneys; albumin in the urine is the early sign (KDIGO 2022) Urine and blood tests at least once a year, and 1–4 times a year once you have kidney disease (ADA 2026 §11, recommendation 11.1b); ask about kidney-protecting medicines
Stages G3b–G5, not on dialysis Lows become more common; insulin needs often fall (ADA–KDIGO 2022) Share CGM reports at every visit; glucagon at home
Hemodialysis Glucose often falls during a session, and most lows come in the 24 hours after it (JBDS–Renal Association; JBDS 2022) Insulin on dialysis
Peritoneal dialysis Sugar in the fluid raises glucose; one fluid fools some meters (JBDS 2022) Insulin on dialysis
After a transplant Steroids and anti-rejection medicines raise glucose (KDIGO 2009 transplant, chapter 15) After a transplant

Insulin is always needed

Some people with type 2 diabetes on dialysis need less glucose-lowering medicine, or none for a while. This is sometimes called "burnt-out diabetes" (JBDS–Renal Association). UK dialysis guidance says it does not happen in type 1 diabetes (JBDS 2022). With type 1 diabetes your body makes no insulin of its own, and insulin is the treatment at every stage (ADA 2026 §9, recommendation 9.1; KDIGO 2022). Even when you are ill or not eating, do not stop or hold your basal insulin; your team tells you how to adjust it (ADA 2026 §6). Without insulin, ketones build up and DKA can follow (Sick days).

Glucose and potassium are linked

Insulin moves potassium into your cells. Missing insulin or running high glucose can push blood potassium up, even if you ate nothing new (KDIGO 2024, Table 25; Sousa 2016). Getting insulin back on board is what brings it down, so after a pump site that failed overnight, or a run of very high readings, fix the insulin first and follow your sick-day plan. Tell your team if you already have a potassium limit, have had high potassium before, or take an ACE inhibitor, ARB or finerenone: they may want a blood test. This is not a reason to cut fruit and vegetables if your team has not asked you to; KDIGO does not support limiting potassium-rich foods in earlier kidney disease (KDIGO 2024, section 3.11.5). See Blood potassium.

What to do

  • Treat every low at once. Carry glucose tablets everywhere (Treating a low).
  • Ask for glucagon and show your family how to use it (ADA 2026 §6, recommendation 6.16).
  • Use a CGM if you can. ADA recommends one for everyone who uses insulin (ADA 2026 §7, recommendation 7.15).
  • Ask to be checked each year for not feeling your lows (ADA 2026 §6, recommendation 6.11).
  • Tell your diabetes team when your kidney function changes, when dialysis starts or changes, after a transplant, and when you start steroids.
  • Get a written sick-day plan (Sick days).
  • Ask whether you should take an ACE inhibitor, ARB or finerenone (Kidney-protecting medicines).
  • Log meals and low treatments in the app, and take the report to your visits (Logging food; Reports for your team).

Examples

  • Night lows at stage G4. Sam's CGM shows lows around 3 a.m. on four nights in two weeks, and he slept through two of them. He treats each low, turns on his low alarm, and sends the CGM report to his diabetes team the same week. The team changes his insulin plan. He does not change it himself.
  • A failed pump site. Rosa's glucose ran above 250 mg/dL (13.9 mmol/L) overnight because her infusion set had come out. She changed the set, found ketones of 0.8 mmol/L, followed her sick-day plan and rechecked 2 hours later. Her potassium the next morning was higher than usual. The high glucose and missing insulin were part of the reason, not only food.
  • Feeling fine at 55. Joe's CGM alarm goes off at 55 mg/dL (3.1 mmol/L), but he feels nothing. He treats the low at once. Then he asks his team about awareness screening and about setting his alarms higher.

Ask your care team

  1. My kidney function has changed. Does my insulin plan need to change?
  2. Am I having more lows than before? Can you look at my CGM report with me?
  3. Should I be screened for not feeling my lows?
  4. Is my A1c still reliable, or should we use CGM numbers instead?
  5. Please prescribe glucagon and write down my sick-day plan.
  6. Should I take a kidney-protecting medicine?

Get help now if…

  • A low the person cannot treat themselves (cannot swallow, very drowsy, fitting): give glucagon and call 911 (or your local emergency number) (Treating a low).
  • Blood ketones 3.0 mmol/L or more, or any ketones with vomiting so you cannot keep fluids down: call 911 or go to the emergency department (Sick days).
  • Lows that keep coming back, or lows you no longer feel: call your diabetes team today. See Get help now.
For your clinician: insulin and declining kidney function (background, from the diet guide)

Background only; dose decisions are the prescriber's. The kidney clears a large share of injected insulin and, through gluconeogenesis and tubular reabsorption, contributes about 20 % of total body glucose (Pecoits-Filho); both fall with eGFR. For T1D the ADA–KDIGO consensus states insulin doses "may need to be decreased … due to reduced insulin clearance" (ADA–KDIGO 2022); its phrase "a risk factor for hypoglycemia" refers to advanced CKD in T2D, and ADA 2026 Table 6.5 lists CKD and kidney failure as hypoglycemia risk factors for everyone (ADA 2026 §6). Pecoits-Filho et al. review older dose-adjustment guidance by GFR, differences between basal insulin analogues, and note that a restricted renal diet itself "reduces hepatic gluconeogenesis" (Pecoits-Filho 2016; the dose figures are deliberately not repeated in this patient handbook). Cardiovascular autonomic neuropathy (about two-thirds of people with advanced CKD in that series) blunts counter-regulation; ADA 2026 asks for at least annual screening for impaired hypoglycemia awareness (Rec 6.11) (ADA 2026 §6; Pecoits-Filho 2016). JBDS 2022 suggests real-time CGM for people on dialysis with recurrent hypoglycemia or lost awareness (Rec 2.9) and CGM-guided adjustment on dialysis and non-dialysis days (Rec 3B.5) (JBDS 2022). On the potassium side: insulin deficiency and hyperglycemia both raise serum potassium, diabetic nephropathy is the commonest cause of hyporeninemic hypoaldosteronism, and ACE inhibitors, ARBs and finerenone all raise potassium, so a run of high readings, a missed basal dose or a new RAAS or MRA prescription are reasons to restore insulin first and to consider an earlier potassium check, particularly in people already on a potassium limit; KDIGO 2024 (section 3.11.5) does not endorse restricting foods naturally rich in potassium in earlier CKD (KDIGO 2022; KDIGO 2024; Sousa 2016).

Sources

Not yet reviewed by a clinician. Facts and sources last checked 2026-10-06.