blood sugar rises having taken insulin and not eaten. diabetes 2 insulin dependent & polymyalgia rheumatica


(ireland)




QUESTION:


From Ireland


I am 60 and have insulin-treated type 2 diabetes, retinopathy, giant cell arteritis and polymyalgia rheumatica. My diabetes is hard to control and I inject insulin four times daily. Why can my blood sugar continue rising after I have taken insulin and have not eaten?




Quick Answer


Blood glucose can rise without food because the liver releases stored glucose, especially overnight, during illness, stress or steroid treatment. Prednisolone—commonly used for polymyalgia rheumatica and giant cell arteritis—raises insulin resistance and liver glucose output, so usual insulin doses may no longer match your needs. The pattern also depends on whether the injection was rapid-acting or basal insulin, its timing, injection technique and the steroid dose. Do not stop prednisolone or change insulin doses independently. Contact your diabetes team promptly for a steroid-specific insulin plan and continuous glucose monitoring review.



Answer by Dr. Albana Greca, MD, MMedSc


Hello,


Not eating does not stop glucose production. During fasting, hormones tell the liver to release glucose. In type 2 diabetes, insulin resistance can let this output exceed insulin coverage.


Prednisolone Is a Likely Contributor


PMR is usually treated with prednisolone, while GCA often requires higher doses. Glucocorticoids can:



  • Increase glucose production by the liver

  • Reduce glucose uptake by muscle and fat

  • Increase insulin resistance

  • Increase the amount of insulin needed to control glucose


Morning prednisolone often causes the greatest rise from late morning through evening. Multiple doses or longer-acting steroids may raise glucose overnight.


Insulin is commonly used for steroid-related hyperglycemia, matched to the steroid dose, timing and duration.



Never stop or sharply reduce prednisolone yourself. Giant cell arteritis treatment protects against permanent visual loss and stroke, and long-term steroids usually require gradual tapering to prevent adrenal insufficiency. Changes must be coordinated with rheumatology and your diabetes team.



Which Insulin Did You Take?


Four injections daily often means rapid insulin before meals plus one basal injection.



  • Rapid insulin covers meals and corrections, not full-day background needs.

  • Basal insulin restrains liver glucose release between meals and overnight.

  • Steroid-related rises may require meal, basal or intermediate insulin adjustment.


Do not repeat rapid corrections too closely; insulin stacking can cause a delayed low. See our insulin safety guide.


Other Reasons Insulin May Seem Not to Work



  • Dawn phenomenon: Early-morning hormones stimulate liver glucose output.

  • Illness or inflammation: Infection, pain and an active PMR or GCA flare raise stress hormones.

  • Injection sites: Lumpy tissue causes unpredictable absorption.

  • Insulin damage: Heat, freezing, expiration or incorrect storage can reduce potency.

  • Technique errors: Wrong pen, leakage, blocked needle or incomplete dose.

  • Delayed absorption: High-fat meals or gastroparesis may cause a later rise.

  • A steroid-dose increase, missed basal dose or declining insulin production.


Rotate sites, use a new needle, verify insulin and follow storage instructions. Do not inject into lumps. See our insulin safety page.


Fasting Is Not the Solution


Skipping meals does not stop steroid- or liver-driven glucose and may cause hypoglycemia after meal insulin. Follow your team’s instructions.


If appetite is poor or you cannot eat, use your sick-day plan and contact the diabetes team.


What to Record for Three to Seven Days



  • Glucose before meals, two hours after meals and at bedtime

  • Steroid name, dose and exact time taken

  • Each insulin name, dose and injection time

  • Meals, activity, pain, infection symptoms and overnight readings

  • Any hypoglycemia and how it was treated


CGM can show whether the rise begins overnight, after prednisolone, after meals or when insulin is wearing off.


What to Ask Your Diabetes Team



  • Does the glucose pattern match the prednisolone timing?

  • Should meal, basal or intermediate-acting insulin be adjusted?

  • How should insulin change when the steroid dose is increased or tapered?

  • Can I receive CGM and a written correction and sick-day plan?

  • Are injection sites, kidney function, HbA1c and current insulin supply satisfactory?


Insulin needs may fall quickly when prednisolone is tapered, causing hypoglycemia unless the plan is reviewed.


When to Seek Urgent Help



Follow your sick-day plan and seek urgent advice if glucose remains above about 14–15 mmol/L despite correction, especially with blood or urine ketones. Go to emergency care for vomiting, abdominal pain, deep breathing, severe dehydration, confusion, marked drowsiness or inability to manage glucose and ketones.



New vision loss, severe headache, scalp tenderness, jaw pain, weakness or speech trouble requires immediate assessment for active GCA or another emergency.


Related Questions



Related Pages



This answer does not replace individualized insulin or steroid care.


Click here to post comments or follow up

Ask the Doctor now? Simply click here to return to Diabetes Test and Levels.