by Misty
(Chattanooga, Tn)
QUESTION:
By Misty, Chattanooga, Tennessee
I was diagnosed with type 2 diabetes two years ago. Despite several medicines, my glucose may go from 62 to 240, then 120, 80 and 200 mg/dL in one day. Some days it remains high and other days low. Food and exercise do not seem to explain it, and readings sometimes rise or fall unexpectedly after eating. I have been told I may have brittle diabetes. What could be causing these fluctuations?
Quick Answer
“Brittle diabetes” is an older descriptive term, used mainly for severe, severe glucose instability rather than as a precise diagnosis. Readings from 62 to 240 mg/dL show glucose variability, but the cause must be identified. A value of 62 mg/dL is hypoglycemia and requires immediate treatment. Common explanations include insulin or sulfonylurea dosing, meal timing, alcohol, exercise, inaccurate testing, kidney or liver problems, delayed stomach emptying and incorrect diabetes classification. Ask for an endocrinology review and continuous glucose monitoring rather than simply adding more medicine.
Answer by Dr. Albana Greca, MD, MMedSc
Hello Misty,
These readings need structured investigation but do not prove “brittle diabetes.” The more precise problems are glucose variability, hypoglycemia and hyperglycemia.
Glucose below 70 mg/dL is hypoglycemia. If awake and able to swallow, take about 15 grams of fast carbohydrate, recheck after 15 minutes and repeat if still below 70.
Emergency: Severe confusion, seizure, unconsciousness or inability to swallow requires glucagon when available and emergency services. Do not give food or drink by mouth to an unconscious person.
Frequent lows mean the treatment plan must be reassessed. Do not intentionally keep glucose high to avoid them. Review our low blood glucose guide.
Historically, the term described severe hypoglycemia, hyperglycemia or ketoacidosis, mainly in type 1 diabetes. It has no single diagnostic test.
The label may hide a treatable cause. Clinicians need frequency, meter accuracy, medicines and associated symptoms.
Insulin, sulfonylureas and meglitinides can cause lows when doses do not match food, activity or kidney function. Overtreating a low may then produce a high.
Record every medicine, dose, missed dose, correction, supplement, steroid and alcohol use. Do not repeatedly change doses from isolated readings. See our sulfonylurea guide.
Wash and dry hands, use correct unexpired strips and repeat odd results. Food residue, too little blood or damaged strips can distort readings.
Compare the meter with a laboratory glucose. Confirm CGM values by fingerstick when symptoms do not match. See testing-strip safety.
Carbohydrate, fat, protein and meal timing affect glucose. High-fat meals may delay the peak; alcohol may cause delayed hypoglycemia.
Moderate exercise often lowers glucose. Intense activity may raise it briefly, while increased insulin sensitivity can cause a later low. Record activity type and timing.
Learn about gastroparesis and autonomic neuropathy.
Some adults labeled type 2 have autoimmune type 1 or another form. Reconsider classification with weight loss, ketoacidosis, low body weight, autoimmune disease or rapid failure of tablets.
An endocrinologist may consider islet autoantibodies and C-peptide when the clinical picture is atypical.
HbA1c can hide highs and lows. Personal or professional CGM can reveal overnight lows, meal peaks and exercise effects.
CGM is recommended when insulin, hypoglycemia-causing medicine or useful management data justify it. Review time below range, time in range and variability. See blood sugar by time.
A diabetes educator can help match food, activity and medicine. Requesting endocrinology review or a second opinion is reasonable.
Seek urgent care for persistent glucose around 300 mg/dL or higher with vomiting, abdominal pain, ketones, deep breathing, dehydration, confusion or unusual drowsiness. Ketoacidosis can occur in adults initially labeled as having type 2 diabetes.
This answer does not replace evaluation of recurrent hypoglycemia.
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