Why did my serum glucose increase from 137 to 310 mg/dL?

by Jaime
(texas,willacy)






Question


My levels came high within a 6 month period. Glucose serum went from 137 to 310.


—Jaime, Willacy, Texas





Quick Answer


A serum glucose of 310 mg/dL, or about 17.2 mmol/L, is severe hyperglycemia and needs prompt medical assessment. Contact your clinician the same day. If you have vomiting, abdominal pain, rapid or deep breathing, severe thirst or dehydration, confusion, marked drowsiness, inability to keep fluids down, or positive ketones, seek emergency care.


Do not increase metformin, change another diabetes drug, or begin insulin on your own. Lifestyle changes are important, but a level of 310 should not be managed first with diet and exercise alone.




Answer by Dr. Albana Greca, MD, MMedSc



Hello Jaime,


The meaning of 137 depends on whether you were fasting, but 310 is far above the usual range regardless of meal timing. The rise may reflect new or worsening diabetes, illness, medicine effects, or another cause.



Does Glucose of 310 Mean Diabetes?


Diabetes can be diagnosed with a fasting laboratory glucose of at least 126 mg/dL, HbA1c of at least 6.5%, or a two-hour glucose of at least 200 mg/dL during a 75-gram oral glucose tolerance test.


A random plasma glucose of at least 200 mg/dL together with classic symptoms—such as excessive thirst, frequent urination, or unexplained weight loss—also diagnoses diabetes. Without clear symptoms or a hyperglycemic crisis, abnormal results generally require confirmation.


Even when confirmation is needed, 310 should not wait for a routine future appointment. See our blood-test guide.



What Could Cause the Increase?



  • New or progressively worsening type 2 diabetes

  • Type 1 diabetes or latent autoimmune diabetes in an adult

  • Missed medicine, an incorrect dose, insulin-delivery problems, or expired supplies

  • Infection, fever, inflammation, surgery, pain, or another physical stress

  • Dehydration

  • Corticosteroids, some antipsychotic medicines, and selected other drugs

  • Pancreatic or endocrine disease in selected cases


A high-carbohydrate meal can raise glucose but should not be assumed to fully explain a confirmed value of 310.




When 310 mg/dL May Be an Emergency


Diabetic ketoacidosis and hyperosmolar hyperglycemic state are life-threatening emergencies. Seek immediate care for:



  • Vomiting or inability to drink

  • Abdominal pain

  • Rapid, deep, or difficult breathing

  • Fruity-smelling breath

  • Severe dehydration, weakness, or fainting

  • Confusion, unusual behavior, or marked drowsiness

  • Moderate or high urine ketones or elevated blood ketones


People at risk for ketoacidosis should check ketones during illness or marked hyperglycemia. Suspected hyperosmolar state requires immediate hospital evaluation.




What Should You Do Now?



  1. Contact the clinician managing your glucose today and report the result of 310.

  2. If you have a meter, wash and dry your hands and check again with a new strip.

  3. Check blood or urine ketones if you use insulin, have type 1 diabetes, are ill, or your clinician has instructed you to do so.

  4. Drink water if you can do so safely and have not been placed on a fluid restriction.

  5. Avoid sugary drinks and alcohol.

  6. Continue prescribed medicine unless a clinician or sick-day plan tells you otherwise.


If you use insulin, do not stop basal insulin because you are eating less. Contact the diabetes team for sick-day instructions.



Should You Exercise to Lower 310?


Not before checking for illness and ketones. Strenuous activity can worsen hyperglycemia or ketosis when insulin is insufficient. Avoid vigorous exercise until medically cleared.



Which Tests May Be Needed?


The clinician may order:



  • Repeat plasma glucose and laboratory HbA1c

  • Electrolytes, kidney function, bicarbonate, and anion gap

  • Blood or urine ketones

  • Urinalysis and assessment for infection

  • Medication and insulin-technique review

  • C-peptide or diabetes autoantibodies when the diabetes type is uncertain


HbA1c helps show whether glucose has been elevated for weeks or months. A normal earlier result does not rule out a recent rapid deterioration.



Should Metformin Be Increased or Insulin Started?


That decision requires kidney function, HbA1c, symptoms, hydration, ketones, current medicines, and diabetes type. Increasing metformin yourself will not treat ketoacidosis or severe insulin deficiency.


Insulin may be needed for symptomatic hyperglycemia, ketosis, suspected type 1 diabetes, or treatment failure. It requires an individualized plan. See our treatment guide.



Could the Laboratory Result Be Wrong?


Laboratory errors are possible, but 310 should be treated as real until promptly rechecked.




What to Record for the Appointment



  • Whether the test was fasting or random

  • Symptoms and recent weight change

  • All medicines, including steroids and supplements

  • Recent illness, infection, surgery, or major stress

  • Home glucose readings and ketone results

  • Missed doses or problems obtaining medicine or insulin




Remember: serum glucose rising from 137 to 310 needs prompt evaluation. Do not rely on exercise, herbs, or self-directed medication changes. Confirm it, assess ketones and dehydration, identify the cause, and obtain a treatment plan.




Written by: Dr. Albana Greca, MD, MMedSc, Family Physician

Medically reviewed by: Dr. Ruden Cakoni, MD, Endocrinologist

Last medically reviewed: August 4, 2026


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Safety note: General education only. Glucose of 310 mg/dL with illness, ketones, vomiting, dehydration, breathing difficulty, or mental-status change requires urgent medical care.



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