Why Blood Sugar Can Remain High Even When You're Taking Medication

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Taking diabetes medication regularly but still seeing high blood sugar readings can be frustrating. Some people assume the medicines have stopped working, while others blame themselves for something they ate. In reality, blood sugar is affected by several factors, and medication is only one part of the picture.

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A high reading does not automatically mean treatment has failed. But if the numbers remain above target, it is worth finding out why rather than simply increasing the dose or cutting out more foods. We spoke to Dr Vishwas K, Consultant Physician (Internal Medicine), HOSMAT Hospital, who explained the common reasons behind persistently high readings and what to do about them.

The timing and composition of meals matter

What is eaten matters, but so does how much, when and how often. Large portions of rice, white bread, dosa or other carbohydrate-rich foods can raise blood sugar, particularly when a meal contains little fibre or protein. Sugary drinks, fruit juice and frequent snacking can also push readings up, sometimes without people realising how much they are consuming.

"Skipping meals and then eating heavily later can make glucose levels harder to manage, especially for people taking medicines that can cause low blood sugar. A more consistent meal routine, sensible portions and a combination of vegetables, protein-rich foods and carbohydrates can help. There is no need to eliminate rice or other familiar staples altogether; portion size and the overall balance of the meal matter," explained Dr Vishwas.

Are the medicines being taken as prescribed?

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A missed dose now and then may seem insignificant, but repeated missed doses can affect glucose control. So can taking medication at the wrong time. Some medicines need to be taken with food, while others have different timing instructions.

"Cost, side effects, a complicated prescription, or simply forgetting can make regular treatment difficult. These are worth discussing openly with a doctor. If tablets are missed because they cause nausea or other discomfort, the answer is not to stop them without advice. The prescription may need to be adjusted," added Dr Vishwas.

Poor sleep, stress and illness can raise sugar levels

Blood sugar is not determined by food alone. During an infection, fever or other illness, the body releases stress hormones that can push glucose levels higher. Even a urinary tract infection or dental infection may affect control.

"Poor sleep and ongoing stress can also interfere with the hormones involved in regulating blood sugar. People who sleep badly, work irregular hours or have sleep apnoea may find their readings harder to manage. Some medicines, including corticosteroids such as prednisolone, can raise blood glucose too," warned Dr Vishwas. A doctor should be told about all medicines being taken, including those prescribed for other conditions.

Diabetes treatment may need a review

Type 2 diabetes is a progressive condition for many people. Over time, the pancreas may produce less insulin, and the body may become less responsive to the insulin it makes. A treatment plan that worked well a few years ago may no longer be enough.

"Doctors look at patterns, not just one reading. Fasting sugar may be high while post-meal readings are closer to target, or the reverse may be true. An HbA1c test, which reflects average blood glucose over roughly two to three months, can help show whether overall control is improving," said Dr Vishwas.

Depending on the readings, symptoms, kidney function and other health factors, the doctor may change the dose, switch medicines or add another treatment, including insulin when needed. This is a routine part of diabetes care, not a sign that someone has failed.

When should medical advice be sought?

If blood sugar remains above the target set by the treating doctor, arrange a review rather than adjusting medication independently. Keep a record of readings, meal timings, missed doses and any recent illness; this can help identify a pattern.

"Very high readings accompanied by vomiting, abdominal pain, rapid or deep breathing, marked drowsiness or confusion need urgent medical attention. People who are unwell and have persistently high glucose should seek prompt advice, particularly if they use insulin or have been given a sick-day plan," advised Dr Vishwas.

He concluded, "The key is to look beyond the number on the glucose meter. Food, medication timing, sleep, illness and changes in the body can all play a role. With the cause identified and treatment reviewed when necessary, blood sugar can often be brought closer to the individual's target."

Disclaimer: The information provided in this article is for general informational and educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or a qualified healthcare provider with any questions you may have regarding a medical condition.