Creatinine and Kidney Test for Diabetes: eGFR and Urine ACR Explained
Your diabetes report has a creatinine value circled in red and a word you’ve never heard, “microalbumin”, and the lab slip gives no explanation. This guide walks through the yearly kidney test for diabetes line by line: creatinine, eGFR and the urine albumin-to-creatinine ratio (ACR), what each number means, and what to ask the doctor.
Quick facts
- Two tests, every year: a blood test (creatinine, turned into eGFR) and a urine test (ACR).
- eGFR: 90 or above normal; 60 to 89 mildly reduced; under 60 for three months or more means chronic kidney disease.
- Urine ACR: under 30 mg/g (under 3 mg/mmol) normal; 30 to 300 moderately raised; over 300 severely raised.
- Biggest avoidable harm: regular painkillers like diclofenac and ibuprofen.
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Why Diabetes Reaches the Kidneys
Each kidney holds around a million tiny filters, and years of high sugar and high blood pressure wear them down slowly, quietly and without the slightest pain, so that by the time swelling, tiredness or foamy urine shows up, a lot of filtering power can already be gone. That’s the whole case for testing: kidney damage from diabetes is silent early, and early is when protecting the kidneys works best.
The early warning signs of kidney disease piece covers symptoms. This one is about the paper report.
Creatinine: The Number on the Blood Report
Creatinine is a waste product from muscle. Kidneys clear it. When filtering slows, the blood level rises. Labs commonly quote an adult range somewhere around 0.6 to 1.2 mg/dL, a little lower for women, but the raw number misleads on its own.
Why? Muscle. A thin, elderly grandmother with little muscle can have a “normal” creatinine of 1.0 mg/dL and already have kidneys working at half capacity. A young gym-going man can read 1.3 with perfectly healthy kidneys, and a big nihari or meat meal the night before, or a tub of creatine powder from the gym shop, can nudge the number up a little more, which is why labs now convert creatinine into something far more useful. Enter eGFR.
eGFR: The Kidney Percentage That Actually Helps
The estimated glomerular filtration rate uses creatinine, age and sex to estimate how much blood the kidneys filter per minute. Roughly, think of an eGFR of 60 as kidneys working at about 60% of a young adult’s. Rough, but useful.
| eGFR | What it usually means |
|---|---|
| 90 or above | Normal filtering (still check the urine test) |
| 60 to 89 | Mildly reduced; common with age |
| 45 to 59 | Mild to moderate kidney disease if lasting 3 months |
| 30 to 44 | Moderate to severe |
| 15 to 29 | Severe; specialist care |
| Under 15 | Kidney failure |
One low result is not a diagnosis. Dehydration from diarrhoea, a fever, or a hot day in June can drop eGFR for a while. Chronic kidney disease means the number stays under 60, or the urine test stays abnormal, for at least three months.
Urine ACR: The Early Warning Most People Skip
This is the test that catches trouble years before eGFR falls. Years. Damaged filters leak a protein called albumin into the urine. The albumin-to-creatinine ratio (ACR, sometimes printed as “urine microalbumin”) measures that leak in a small sample, usually the first urine of the morning.
- Collect a mid-stream sample, ideally first thing in the morning, in the lab’s sterile container.
- Avoid heavy exercise the day before; a long run or a day of heavy lifting can raise albumin for a while.
- Postpone the test if you have a fever, a urine infection, or are on your period, since each can give a false high.
- Expect the doctor to repeat a raised result: two of three samples over 3 to 6 months need to be high before it’s called persistent.
Under 30 mg/g is normal, while a result between 30 and 300, which older reports and older doctors still call microalbuminuria, is now labelled “moderately increased”, and anything over 300 is severely increased and usually brings a referral. Labs that report in mg/mmol use 3 and 30 as the same lines.
A raised result is a reason for a doctor’s review, not for changing medicines at home. Don’t stop metformin, BP tablets or anything else because of a kidney number; the doctor adjusts or switches medicines according to your eGFR, and some BP medicines are chosen precisely because they protect the kidneys. See a doctor within days, not weeks, if you notice swelling of the legs or face, much less urine than usual, breathlessness, or blood in the urine. Go to emergency care for passing almost no urine, severe vomiting, confusion or chest pain. Painkillers bought over the counter need special care: skip diclofenac, ibuprofen, naproxen and similar anti-inflammatories unless your doctor has said they’re safe for you.
Painkillers, Dehydration and Other Kidney Hits
In our part of the world, one of the most common kidney hits is the humble painkiller. Diclofenac injections for back pain from the local dispensary, ibuprofen for joint aches every day, combination “body pain” tablets from the chemist: anti-inflammatory painkillers reduce blood flow to the kidney and are a classic cause of sudden kidney injury in diabetics, especially if dehydrated or on certain BP pills and water tablets at the same time. Paracetamol is generally the gentler choice for kidneys, used as the pack or pharmacist directs.
Other hits worth knowing:
- Diarrhoea and vomiting: dehydration plus certain diabetes and BP medicines is a risky mix. The doctor may give you “sick day rules” for which medicines to pause during illness; ask for them in advance. Our winter diabetes guide covers sick days too.
- Contrast scans: tell the radiology team you have diabetes and your eGFR before a CT with dye.
- Herbal and “kidney cleansing” products: some contain heavy metals or plants that harm kidneys. Our verdict on “cleansing” waters for liver and kidneys explains why kidneys don’t need cleansing products.
- High-protein fads: with reduced eGFR, ask before protein powders or very high-protein diets.
Your kidney page
Keep one page in your diabetes file with three columns: date, eGFR, ACR. Nothing fancy. After three years, the trend tells you and the doctor far more than any single number. Add BP and HbA1c on the same line, because these two are what move the kidney numbers.
Questions to Ask at the Kidney Review
What is my eGFR, and is it stable or falling? What is my ACR? Is my BP at the target you want for my kidneys? Do any of my medicines need adjusting at this eGFR? Should I see a nephrologist? Which painkillers are safe for me? Write the six answers down. Numbers for sugar and BP are explained in blood sugar numbers in plain words, and there’s more on the Diabetes and Blood Pressure hub.
Creatinine and Kidney Test Questions
What is the normal creatinine level?
Many labs quote roughly 0.6 to 1.2 mg/dL for adults, a little lower for women. Because creatinine depends on muscle, your eGFR is a better guide to how well your kidneys work.
Which kidney test for diabetes should I get every year?
Two: a blood test for creatinine with eGFR, and a urine albumin-to-creatinine ratio (ACR). Both are needed, because either can be abnormal while the other is normal.
What does eGFR 60 mean?
An eGFR of 60 means the kidneys filter at roughly 60% of a young adult’s rate. If it stays under 60 for three months, that’s classed as chronic kidney disease.
What is microalbumin in urine?
It’s the old name for a small albumin leak, now reported as a urine ACR of 30 to 300 mg/g. It’s an early sign of kidney damage in diabetes and needs a doctor’s review.
Can creatinine go back to normal?
A rise caused by dehydration, illness or a painkiller often improves once the cause is dealt with. Long-standing damage usually doesn’t reverse, but good sugar and BP control can slow further loss.
Is metformin bad for kidneys?
Metformin doesn’t damage kidneys, but it builds up if kidneys are weak, so doctors adjust or stop it at lower eGFR. Don’t change it yourself; your doctor decides based on your results.
Which painkiller is safe for kidneys?
Paracetamol, used as directed on the pack, is generally the kidney-friendlier choice. Avoid diclofenac, ibuprofen and similar anti-inflammatories unless your doctor says they’re safe for you.
Does drinking more water lower creatinine?
If you were dehydrated, drinking enough brings it back down. Beyond that, extra water doesn’t improve kidney function, and people with advanced kidney disease may be told to limit fluids.
Can diet help diabetic kidney disease?
Yes: less salt, sensible protein and good sugar and BP control help. People with low eGFR may need potassium or phosphate limits set by a doctor or renal dietitian.
When should I see a kidney specialist?
Usually when eGFR is under 30, ACR is over 300, eGFR is falling fast, or there’s blood in the urine. Your doctor will refer you.