by patricia nelson
(Norcross, Ga)
Answer by Dr. Albana Greca, MD, MMedSc
Hello Patricia,
Based on the numbers you have provided, your glucose control appears quite good. The important point is that a glucose reading should always be interpreted according to when you tested. A fasting reading, a before-meal reading, and an after-meal reading do not mean exactly the same thing. You can see this more clearly in my guide to blood sugar levels.
For many nonpregnant adults with diabetes, the following targets are commonly used. Your own doctor may set different goals depending on your health, treatment, and risk of low blood sugar.
| Measurement | Common Target |
|---|---|
| Before meals | 80–130 mg/dL |
| Peak after meals | Below 180 mg/dL |
| Low blood sugar | Below 70 mg/dL |
Your range of 70–128 mg/dL therefore falls mostly within or very close to the usual pre-meal target. An average of approximately 100 mg/dL is also encouraging.
A glucose of exactly 70 mg/dL is right at the lower boundary. A reading below 70 mg/dL is considered low blood sugar and should be treated according to your diabetes care plan.
If you repeatedly reach 70 mg/dL or lower, especially with sweating, shaking, hunger, weakness, dizziness, palpitations, blurred vision, or confusion, let your doctor know.
Metformin by itself has a relatively low risk of causing hypoglycemia. The risk can be higher when it is combined with insulin or certain other diabetes medicines, or when someone eats very little or exercises more than usual.
Not immediately. Metformin does not behave like rapid-acting insulin. It works mainly by reducing the amount of glucose released by the liver and improving the body's response to insulin over time.
Therefore, if you take your tablet and test your glucose shortly afterward, the reading still gives useful information about your pre-meal glucose. The tablet you have just swallowed has not suddenly produced that particular reading.
The correct timing depends on the type of metformin and the schedule prescribed for you. Immediate-release metformin is commonly taken with meals, while some extended-release preparations are taken once daily, often with the evening meal.
Since you recently changed from taking metformin at night to taking it in the morning, I would check the instructions on your prescription or confirm the timing with your doctor or pharmacist. I would not recommend changing the timing repeatedly based only on individual glucose readings.
Your home meter tells you what your glucose is at a particular moment. Your HbA1c, on the other hand, gives us a broader picture of your average glucose exposure over approximately the previous two to three months.
For many adults with diabetes, an HbA1c below 7% is a common goal, although the safest target should always be individualized. If your HbA1c is also within your personal target, your home readings averaging around 100 mg/dL would generally support the impression that your diabetes is well controlled.
Looking at a pattern over several days is more useful than trying to judge your control from one reading. Food, physical activity, stress, sleep, illness, and medication timing can all cause normal day-to-day variation.
Patricia, based on the information you gave me, a blood glucose range of 70–128 mg/dL with an average around 100 mg/dL is generally satisfactory, particularly if these are before-meal readings.
I would not try to push your glucose lower simply because you occasionally see a reading above 100. Instead, pay attention to the overall pattern, watch carefully for values below 70 mg/dL, check your HbA1c, and make sure the morning timing of your metformin is appropriate for the formulation you have been prescribed.
Last medically reviewed: August 2026
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