Insulin and Steroids
By Ryan Mitchell · Referenced against inpatient diabetes management literature · Updated July 2026
Why steroids raise glucose
Glucocorticoids work against insulin on several fronts at once. They increase hepatic glucose production, reduce glucose uptake in muscle and fat, and interfere with insulin signalling directly. The result is a person whose insulin has become measurably less effective in the space of a day, without anything about their diabetes having changed.
The published figure for the scale of it is an increase of roughly 50% above that person’s own baseline, with total requirements commonly reaching 0.5 u/kg/day and frequently exceeding 1.0 u/kg/day. That is a large change — it is why someone stable for years can suddenly look uncontrolled after starting prednisone for something unrelated.
The pattern is uneven, and that matters
Steroid hyperglycemia does not spread evenly across the day, and treating it as though it does is the most common mistake.
With a single morning dose of an intermediate-acting steroid such as prednisone, the glucose-raising effect builds through the day and peaks in the afternoon and evening, then fades overnight. Fasting glucose the next morning can look almost normal. Someone who responds by increasing their basal insulin — the intuitive move when readings are high — is adding insulin to the part of the day that was least affected, and risks a nocturnal low while the afternoon stays high.
The pattern differs by steroid. Dexamethasone is longer-acting and produces a flatter, more sustained rise across 24 hours. Divided daily dosing does the same. Which is why the practical question is not just how much extra insulin, but when.
| Steroid pattern | Glucose effect | Insulin usually needing most adjustment |
|---|---|---|
| Prednisone, single morning dose | Rises through the day, peaks afternoon/evening, fades overnight | Lunch and evening mealtime doses |
| Prednisone, divided doses | Flatter, more sustained | Both basal and mealtime |
| Dexamethasone | Long-acting, sustained across 24 hours | Basal and mealtime together |
| Antenatal betamethasone | Sharp rise over roughly 1–5 days | Short-term, often substantial across the day |
Coming down is the dangerous part
Insulin requirements fall as the steroid is tapered or stopped, and they can fall quickly. An insulin regimen that was correct at full steroid dose becomes an overdose within a day or two of a significant reduction.
This is where people get hurt, because the direction of attention is wrong. The rise is obvious — readings climb, the problem announces itself, everyone adjusts. The fall is silent until it produces a hypo. Anyone whose insulin was increased for steroids needs a plan for reducing it again, agreed at the same time as the increase rather than left to be worked out later.
The same applies to short courses. A five-day course of prednisone for a chest infection can double someone’s insulin needs and then return them to baseline within 48 hours of the last tablet.
Two situations worth naming
Antenatal betamethasone. Given to accelerate fetal lung maturity before preterm delivery, it produces a sharp and predictable rise in insulin requirement over the following days, in a patient population where tight control matters. It is common enough to have its own protocols — our betamethasone adjustment calculator models the day-by-day pattern.
Steroid-induced diabetes. Glucocorticoids can push someone with no diabetes diagnosis into hyperglycemia, and someone with prediabetes into frank diabetes. It frequently resolves when the steroid stops, but not always, and it is not always looked for. Anyone on prolonged steroids is worth monitoring regardless of their starting glucose status.
Limitations & Safety Notes
- The ~50% increase is a population figure. Individual response varies widely and cannot be predicted from the steroid dose alone.
- The timing of the glucose rise depends on which steroid, what dose, and how it is divided through the day — so the same total extra insulin can be right or wrong depending on when it is given.
- Requirements fall as the steroid is tapered. A plan for reducing insulin should be agreed at the same time as any increase.
- Raising basal insulin in response to afternoon highs from a morning steroid dose risks nocturnal hypoglycemia, because the overnight period is the least affected.
- These are prescriber decisions. Do not adjust insulin around a steroid course without direct clinical guidance.
Frequently Asked Questions
How much do steroids raise insulin requirements?
Published inpatient figures put the increase at roughly 50% above the person’s own baseline, with total daily requirements commonly reaching 0.5 u/kg and frequently exceeding 1.0 u/kg. Individual response varies considerably.
Why is my blood sugar high in the afternoon on prednisone?
A single morning dose of prednisone produces a glucose-raising effect that builds through the day and peaks in the afternoon and evening, then fades overnight. That timing is characteristic, which is why the afternoon and evening doses usually need the most adjustment rather than the basal.
Should I increase my basal insulin on steroids?
Often not, or not primarily. With a morning steroid dose the overnight period is the least affected part of the day, so increasing basal to fix afternoon highs risks a nocturnal low. Mealtime doses are usually the better target — but this is a decision for your prescriber.
What happens when the steroid is stopped?
Insulin requirements fall, sometimes within a day or two. An insulin dose that was correct at full steroid dose can become an overdose during a taper, so the reduction plan matters as much as the increase.
Do steroids cause diabetes?
They can cause hyperglycemia in people without diabetes, and can tip prediabetes into diabetes. It often resolves after the steroid stops, though not always. Monitoring during prolonged courses is worthwhile regardless of starting glucose status.
Does it matter which steroid?
Yes. Dexamethasone is long-acting and produces a flatter, sustained rise across 24 hours, whereas a single morning dose of prednisone concentrates its effect in the afternoon and evening. The pattern determines which insulin doses need changing.
Sources
- Endotext / NCBI Bookshelf. Inpatient Diabetes Management. Link — the ~50% requirement increase and 0.5 to >1.0 u/kg figures
- American Diabetes Association. 16. Diabetes Care in the Hospital: Standards of Care in Diabetes — 2026. Diabetes Care. 2026;49(Suppl 1):S339. Link — inpatient glucocorticoid guidance
- American Diabetes Association. Standards of Care in Diabetes — 2026. Diabetes Care. 2026;49(Suppl 1). Link
Last reviewed: July 2026