Very high blood sugar levels even while on insulin....Really Worried

How Serious Are Blood Sugars in the 400s?

Glucose repeatedly above 300–400 mg/dL represents significant hyperglycemia. It can cause dehydration and electrolyte disturbances and may progress to a hyperglycemic emergency, particularly if ketones or acidosis develop.

Because your readings have reached 496 mg/dL and you have already needed hospital care for dehydration, this is more serious than an isolated high reading. Our guide to
blood sugar over 400 mg/dL
explains why persistent values in this range require close medical attention.

When Should You Check Ketones?

People at risk of diabetic ketoacidosis may be advised to check blood or urine ketones when glucose is very high or during illness. Ketones are especially concerning when high glucose occurs with nausea, vomiting, abdominal pain, dehydration, rapid or difficult breathing, unusual drowsiness or confusion.

DKA is a medical emergency and can occur in people with type 1 diabetes and, less commonly, in people with type 2 diabetes who have severe insulin deficiency. :chatgpt-content-reference{index="1"}

Why Might Insulin Not Be Bringing the Glucose Down?

Several problems can contribute, including an insulin dose that still needs adjustment, infection or illness, missed or ineffective insulin, injection-site problems, incorrect storage, medication effects, severe insulin resistance or uncertainty about the type of diabetes.

Persistent readings this high despite insulin are a reason for your diabetes team to review the entire treatment plan, not simply the carbohydrate content of your meals.

Do Not Increase Insulin on Your Own

Use only the correction plan and dose adjustments prescribed by your clinician. Taking extra insulin without a clear plan can later cause severe hypoglycemia.

Keeping a structured record of fasting, before-meal and post-meal readings can help your clinician identify patterns. The steps in our
home blood glucose monitoring guide
can also help make those readings more reliable.

Should You Exercise When Glucose Is Very High?

Regular exercise is important once glucose is reasonably controlled, but strenuous exercise should not be used to try to force very high glucose down. When insulin is insufficient and ketones are present, exercise can worsen hyperglycemia and ketosis.

Current guidance advises avoiding exercise when hyperglycemia is accompanied by significant ketones. :chatgpt-content-reference{index="2"}

What About the Painful Injection Sites?

Repeated injections into the same small area can cause bruising, tenderness and changes in fatty tissue that may interfere with insulin absorption. Ask your diabetes nurse or clinician to examine your injection sites and show you safe site rotation and needle technique.

Can the Hair Grow Back?

Hair loss can have many causes. Severe illness, rapid weight loss, major metabolic stress, thyroid problems, nutritional deficiency and poorly controlled diabetes can all contribute. When the underlying trigger is corrected, some forms of temporary hair shedding can improve, but the cause should be evaluated rather than assuming diabetes is the only explanation.

Our discussion of
diabetes and hair loss
explains some of the possible connections.

My Practical Advice

With readings repeatedly in the 300s and 400s despite insulin, please stay in close contact with your diabetes clinician and seek same-day medical advice when levels remain very high. Ask specifically about ketone testing, insulin technique, injection-site rotation, hydration, possible infection and whether your diabetes classification and insulin regimen need reassessment.