Does insulin damage the kidneys?
Medically reviewed by Dr. Om J Lakhani on 18 Oct 2026 · Updated 18 Oct 2026
Short answer
No, insulin does not damage the kidneys, while long-standing high blood sugar and high blood pressure do. Good sugar control, including with insulin when needed, lowers the risk of diabetic kidney disease, and insulin is often one of the safest options for people whose kidneys are already weak. The myth arises because insulin is often started late, when kidney damage has already happened.
Many people in India refuse insulin because a relative “started insulin and then went on dialysis”. It is easy to see why this story spreads, but it confuses cause and effect.
What actually damages the kidneys in diabetes?
The kidneys filter blood through millions of tiny blood vessels. Years of high blood sugar and high blood pressure injure these vessels. Smoking, obesity and high cholesterol add to the damage. This is called diabetic kidney disease, and it is one of the commonest reasons for dialysis in India.
Does insulin protect the kidneys?
Insulin lowers sugar, and lower sugar protects the kidneys. In the landmark DCCT trial in type 1 diabetes, intensive insulin treatment reduced the development of kidney damage, measured as protein leaking in the urine. In the UKPDS trial in type 2 diabetes, tighter control with sulfonylureas or insulin also reduced small blood vessel complications. Insulin itself is a natural hormone and is not toxic to the kidneys.
Why does the myth persist?
Insulin is often started late, after years of high sugars, when kidney damage has already begun. As kidney function falls, many tablets become unsuitable, so doctors switch to insulin. Insulin then gets blamed for a decline that was already underway.
Is insulin safe if my kidneys are already weak?
Yes, it is often one of the safest choices. The kidneys help clear insulin, so when kidney function falls, insulin lasts longer and the same amount can cause low sugars. That is why your doctor will review your plan as your kidney tests change. Do not change your insulin on your own.
Today, protecting the kidneys also involves controlling blood pressure and using medicines shown to slow kidney disease, which your doctor will discuss with you. Read starting insulin: what to expect, learn about your HbA1c target, and keep your insulin working well by storing it correctly in the heat.
Read the full guide: Starting insulin: what to expect and common myths
When to see an endocrinologist
- Swelling of the feet or face, foamy urine or passing much less urine
- Your kidney tests (creatinine, eGFR or urine albumin) are getting worse
- More frequent low sugars, which can happen when kidney function falls and needs a review of your treatment
Chest pain, fainting, severe breathlessness or confusion: call 108 or 112, or go to the nearest emergency department.
Book In-Person / Online ConsultationReferences
- American Diabetes Association. 11. Chronic kidney disease and risk management: Standards of Care in Diabetes 2026. Diabetes Care 2026 (PMID 41358881)
- Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993 (PMID 8366922)
- UK Prospective Diabetes Study Group. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet 1998 (PMID 9742976)
This page is general health information and does not replace a consultation with your own doctor. Please read our medical disclaimer.