Taking Metformin with BSL between 130 and 150 mg/dl

by Ayman
(Dubai, UAE)

Question

Hi,

I was diagnosed with Diabetes II one week ago and the doctor gave me a medication based on Metformin. Before I started taking that medication my blood sugar level was between 130 and 150 using my home test tool.

After taking the medication for 5 days, I check my sugar level after I wake up and I find it 200+.

I have a feeling that this medication I am taking is messing up my sugar level in the blood.

What should I do?

Thanks!

—Ayman, Dubai, UAE

Quick Answer

Ayman, metformin usually lowers blood glucose; it does not normally cause fasting glucose to rise above 200 mg/dL. However, a new fasting home-meter reading above 200 mg/dL should be checked again correctly and discussed with your doctor promptly.

Do not stop metformin or change the dose yourself. Wash and dry your hands, repeat the test with a new compatible strip, and contact the prescribing doctor if it remains high—especially with such a recent diagnosis.

Answer by Dr. Albana Greca, MD, MMedSc

Hello Ayman,

I understand why the sudden increase in your blood sugar levels worries you. Metformin does not stimulate insulin release. It mainly reduces liver glucose production and improves insulin sensitivity, so it would be unusual for metformin itself to cause this rise.

First, Confirm the Reading

One unexpected meter result may be affected by testing technique, sugar on the fingers, expired strips, or meter problems.

Wash your hands with soap and water and dry them completely.

Use a new strip that matches the meter and is not expired.

Repeat the test from a fingertip.

Record the result, time, last meal, medicine dose, and any symptoms.

If the repeat fasting reading remains above 200 mg/dL, contact your doctor and bring the meter for comparison with a laboratory test.

Why Might Glucose Rise After Starting Treatment?

The timing does not prove that metformin caused it. Possible explanations include:

Diabetes was already more severe than the earlier home readings suggested.

The earlier readings may have been taken at a different time or may not have been truly fasting.

The starting dose may be intentionally low and still being adjusted for tolerance.

A high-carbohydrate dinner, late snack, dawn phenomenon, poor sleep, stress, dehydration, infection, or steroid medicine may raise morning glucose.

The meter or strips may have produced an inaccurate result.

The diagnosis or diabetes type may need reassessment, especially with weight loss, ketones, or rapid worsening.

For many nonpregnant adults, a common premeal target is 80–130 mg/dL, although personal targets differ. A fasting reading above 200 mg/dL is high. See fasting blood sugar 127–200 mg/dL and high morning blood sugar causes.

Does Metformin Need More Time?

Metformin is often started low and increased gradually for glucose response and stomach tolerance. Five days may be too early to judge it, but fasting glucose above 200 mg/dL still needs prompt review.

What I Recommend Now

Keep taking metformin exactly as prescribed unless your doctor tells you otherwise.

Repeat the unexpected reading correctly and record fasting and two-hour after-meal readings for several days .

Contact the prescribing doctor promptly if fasting readings remain above 200 mg/dL.

Ask for laboratory fasting glucose, HbA1c, kidney function/eGFR, electrolytes, and—if appropriate—ketone testing or reassessment of diabetes type.

Tell the doctor about thirst, frequent urination, blurred vision, fatigue, infection, vomiting, abdominal pain, unexplained weight loss, or any steroid medicines.

Could the Metformin Dose Be Inadequate?

Possibly, but only your clinician should decide. Dosing depends on the product, kidney function, side effects, glucose pattern, and HbA1c. Some people need another medicine or insulin, especially with symptoms, ketosis, weight loss, HbA1c above 10%, or glucose around 300 mg/dL or higher.

Do not double a missed dose, take extra tablets, or eliminate all carbohydrates. Choose balanced meals, drink water unless fluids are restricted, and follow your treatment plan.

When to Seek Urgent Help

Seek urgent care if high glucose occurs with vomiting, abdominal pain, difficult breathing, fruity breath, confusion, severe drowsiness, inability to drink, dehydration, fainting, or moderate-to-large ketones.

Seek immediate help for severe weakness, muscle pain, abdominal discomfort, breathing difficulty, or increasing sleepiness, especially with kidney problems, infection, dehydration, heavy alcohol use, or recent contrast imaging.

Remember: Metformin is unlikely to be causing the rise. Verify the meter result, continue the prescribed dose, and obtain prompt reassessment if fasting glucose remains high.

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

Last medically reviewed: August 4, 2026