why do sugar say up

by velma thomas
(Monroe La)




Question from Velma:


She takes insulin injections twice a day, but her blood sugar is between 316 and 376 mg/dL every day. I do not know why it stays high or what to do. Can you help?





Emergency Quick Answer


Blood sugar of 316–376 mg/dL, or about 17.6–20.9 mmol/L, every day is very high. Because she uses insulin and the readings remain above 300 mg/dL, contact her diabetes clinician or urgent-care service today for specific instructions.


Check ketones if her care plan recommends it. Go to the emergency department now for moderate or large ketones, vomiting, abdominal pain, deep or difficult breathing, fruity-smelling breath, confusion, extreme sleepiness, fainting, severe weakness, chest pain, dehydration, or inability to keep fluids down.




Answer by Dr. Albana Greca, MD, MMedSc



Hi Velma,



These readings should not be managed only by changing food or waiting for the next appointment. Repeated glucose above 300 mg/dL while using insulin may mean that the body is not receiving enough effective insulin, that illness or another factor is raising glucose, or that the insulin plan needs urgent review.



What to Do Right Now




  1. Wash and dry her hands, then check again. Food or sugar residue can cause a falsely high meter reading.

  2. Check ketones if urine or blood ketone supplies are available and this is part of her diabetes plan.

  3. Follow only her written correction or sick-day plan. Do not guess an extra insulin dose.

  4. Encourage water if she can drink safely and has not been told to restrict fluids because of heart or kidney disease.

  5. Call her diabetes clinician today. Give the readings, insulin names, doses, injection times, ketone result, symptoms, meals, and any illness or new medicine.



Do not stop insulin. Do not double a dose or change the dose without instructions from the clinician managing her diabetes.



Why Can Blood Sugar Stay High Despite Insulin?



Possible causes include:




  • A missed, delayed, incorrect, or insufficient insulin dose

  • Using the wrong insulin or confusing two insulin products

  • Insulin that is expired, frozen, overheated, or stored incorrectly

  • A blocked pen needle, leaking syringe, pump problem, or incomplete injection

  • Repeated injections into hard, lumpy, scarred, or thickened skin

  • Infection, fever, dental problems, wounds, pain, surgery, or another illness

  • Steroid tablets, injections, creams, or some other medicines

  • Dehydration, severe stress, poor sleep, or larger carbohydrate portions

  • A diabetes treatment plan that no longer meets her needs



High glucose is not always caused by eating sweets. Infection or insufficient effective insulin can cause severe hyperglycemia even when a person is eating very little.



Check the Insulin Carefully



Before the clinician calls back, write down the exact insulin names, strengths, doses, and times. Check the expiration date and storage instructions. Insulin should not be used if it was frozen, exposed to excessive heat, or looks abnormal for that product.



Review injection technique with a nurse, pharmacist, or diabetes educator. Use a new needle as directed, inject into recommended tissue, hold the needle in place for the instructed time, and rotate sites. Avoid repeatedly injecting into lumps or hardened areas because absorption may become unpredictable.



Could Illness Be the Cause?



Yes. Urinary, chest, skin, dental, and foot infections can raise glucose, sometimes before obvious symptoms appear. Look for fever, cough, painful urination, new wounds, redness, swelling, pus, dental pain, or unusual weakness.



Tell the clinician about all prescription medicines, over-the-counter products, and recent steroid treatment. Do not stop a steroid or other prescribed medicine without medical advice.



Should She Exercise to Lower It?



No vigorous exercise should be used as a home treatment for readings of 316–376 mg/dL. Exercise can make glucose and ketones rise when there is not enough effective insulin. Check ketones and follow the medical team’s instructions before exercising at this level.



What Information Should You Give the Doctor?




  • Glucose readings, dates, and times

  • Whether readings were fasting, before meals, after meals, or at bedtime

  • Insulin names, doses, and exact injection times

  • Any missed doses or difficulty giving injections

  • Ketone results

  • Symptoms, illness, fever, infection, or dehydration

  • All medicines, especially steroids

  • What she recently ate and drank

  • Whether she is pregnant, elderly, or has kidney or heart disease



A blood sugar log can help the clinician see the pattern and adjust treatment safely.




Important Safety Note


Persistent glucose above 300 mg/dL can lead to severe dehydration, diabetic ketoacidosis, or a hyperosmolar emergency. Do not wait several days to see whether it improves.


If she is a child, pregnant, has type 1 diabetes, uses an insulin pump, or is unable to care for herself, contact her medical team urgently even if symptoms seem mild.





Doctor’s Note


Velma, readings of 316–376 mg/dL every day while taking insulin mean the treatment plan or insulin delivery needs prompt assessment. The safest action is same-day contact with her clinician—not an unplanned dose increase, exercise, herbs, or waiting for the numbers to fall by themselves.





Educational safety note: This answer is for general diabetes education only. It does not replace personal medical advice, emergency assessment, diagnosis, or treatment. Do not start, stop, or change insulin, diabetes medicines, steroids, diet, supplements, or exercise without guidance from the treating healthcare professional.




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Last reviewed: July 2026.



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