What should be the right dose of metformin?
Q: I am a 44 years old female operated for hysterectomy 15 months back and put on insulin. After two months, insulin was stopped and I was put on metformin SR 1000 twice a day. With this, my fasting was 89 mg/dl, PP – 142 mg/dl and random – 108 mg/dl. Again my dose was reduced to metformin 500 three times a day with meals. But I always miss my dose with lunch. Recently, I tested my sugar levels, which showed fasting 180 mg/dl, PP – 256 mg/dl and random – 166 mg/dl. Now, I have started taking metformin SR 1000 in the morning and same dose at night. I walk for 45 minutes every day and am being very strict about my diet too. I am scared that I will be put on insulin again. Why is my fasting level higher than random level? What should be the right dose of metformin? Are glucometer readings credible? Can I continue with metformin 500 three times a day with exercise and diet control?
A:Yes and you can also take SR 1 gm twice a day. This can happen in diabetes as sometimes there is excess release of glucose overnight (hepatic glucose output) which is part of the problem with diabetes. The correct dose of metformin regular or SR is 1 gm (twice a day). Yes, you can go for the lab test.
Metformin (Glycomet / Glyciphage / Riomet / Carbophage / Cetapin) comes in 2 forms - sustained or extended release (SR or XR) or immediate release (IR) or plain form.
This is the first line drug in almost all patients those are overweight. This should be continued all your life except you have more than moderate kidney dysfunction (Creatinine more than 1.5) or side effects to this medication. This is safest medication and we have used this medication for almost 50 years which was originally extracted from plant extract. This medication in diabetes is so important than you should ask your doctor to put him on. This medication is slow acting i.e. it may take weeks before you can notice significant effect on sugar level.
Advantages of Metformin
- This controls sugars or normalises sugars but almost negligible risk of low sugars hypoglycaemia. It also reduces risk of heart diseases.
- It's suitable in most patients and can be used with any other oral diabetes medication and Insulin as well. This works with most of the other medication in diabetes.
- Also safe in most patients who have mild liver or heart problem like heart failure patient as well.
Sustained or extended release (SR or XR form)
It should be used to the maximum tolerated dosages as risk of hypoglycemia is less and benefit is more with higher dosages. We use sustain release formulation (SR or XR) version. We recommend starting 500 mg once a day with dinner and over the next few days (5 to 7) increase with twice a day which can be taken before or after meals or along with the meals. Later we usually recommend increasing to 1000 mg (1gm) twice a day. In caser side effect occur, this can be reduced to lower dosages of 500 mg twice a day.
Immediate release (IR) or plain form
In plain or immediate form of Metformin dose is around 500 mg three times a day with each meal (after or just before) starting with one meal and gradually increasing to three times a day in which can be increased to 850mg three times a day and if well tolerated can be taken up to 1000 mg three time a day.
There almost no long lasting side effect of this medication. This prevents progression of diabetes rather than make you dependent upon medication. Common side effects are usually in first few days of taking it later it wears. This is one of the oldest in use and has the best safety record and beneficial to most patients with diabetes side effect which are common - abdominal pain or discomfort, nausea or vomiting, diarrhoea, not feeling hungry and abnormal taste. These side effects are reversible. If you continue to have side effect than you can reduce to once a day and take after meals with of water or reduce the dosages to half. The risk of hypoglycaemia (low sugars) is almost negligible as long as it’s not being taken with other diabetes drugs.
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