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How long does Metformin take to work

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I am newly diagnosed and am on Metformin 250 mg in morning and 250 at night. Can you tell me how long this take to work. My glucose readings were very high last week...25 average and now down to 17 average. I believe about 5 is normal. I am on a low carb diet and exercising daily.



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Hi Ranelda, welcome to DF. Metformin is one of the oldest T2 drug and it can take weeks to get its full effect. Once your glucose stabilize with your new diet routing, you doctor will then work with you to determine if you need to increase the dosage. The maximum one take is 2550mg per day. :)
DX 02/2002, Minimed 530G(751) w/CGMS on Humalog
Aspirin 81mg + Lipitor 10mg + Losartan 50mg
03/2017 A1C 6.1 Chol=135 Trig=80 HDL=39 LDL=80
08/2016 A1C 5.9 Chol=161 Trig=80 HDL=47 LDL=98
03/2016 A1C 5.9 Chol=153 Trig=90 HDL=50 LDL=85



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I am newly diagnosed and am on Metformin 250 mg in morning and 250 at night. Can you tell me how long this take to work. My glucose readings were very high last week...25 average and now down to 17 average. I believe about 5 is normal. I am on a low carb diet and exercising daily.

Yes, those numbers are very high, and that dose of Metformin is very low, even after it kicks in. In the meantime, I suggest trying to lower those numbers by yourself, through diet and exercise. Cut the carbohydrates out of your diet and do some moderate intensity exercising.




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I think I noticed mine working about 15-20 days. My numbers dropped a lot and have stayed steady since. I take 1000 twice a day though
7-7-11 BG-820 in EmgRoom
7-7-11 A1c 12.8
7-30-11 A1c 10.2
8-19-11 A1c 9.1
9-22-11 A1c 7.8
10-11-11 A1c 7.2
11-10-11 A1c 7.0
12-12-11 A1c 6.8
1-10-12 A1c 6.5

Humulin 100 units 3 times a day



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It can take up to a month to work. Also you are taking a very small amount and may need to increase the dosage. I had to raise mine to 2550 before I saw lower bgs in the morning.
metformin ER 4x500
Moderate carb diet 75-100 carbs

Vit D, CoQ10, Melatonin, Multi vitamin, zinc, B 12
Chia Seeds , Flaxseeds, Hemp seeds, biotin,tumeric, Occuvite, chromium , magnesium, calcium and CoQ10

Exercise- Power Walking- 4-5 miles most days, Hiking in the summer on trails and in the mountains

diagnosed Feb 2007
Age 66
110 pounds



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I've read that Metformin usually takes about 3 weeks to set in, though that may vary from individual to individual, just like it's side effects. As far as dosage is concerned, it does appear to be low for your levels, but let your doctor be the one to decide.
DX Type II Nov 2007 (219 fasting)
Diet/Exercise since Aug 2010
1stAug10 : BG 178 Fasting / A1C : 8.00, Oct'10 6.9 / Jan'11 6.4
Apr'11 6.0 / June'11 5.9 / Oct'11 5.8 / Jan'12 5.6 / Apr'12 5.3
Now between 70-125 all the time



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I've been on metformin 500 mg twice a day since diagnosis, and I saw results the first week. I also made some big changes in my way of eating at that point as well.

T2, diagnosed 8/31/06.
Meds: Metformin-ER 500 mg twice daily, HCTZ 12.5 mg every other day for BP Enalapril 20 mg 1 daily (ace-inhibitor)
Diet: I eat to my meter, generally eating 75-100 carbs/day with the occasional splurge.



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I have read it can take Metformin 3-5 weeks to reach full effect. I take 500 2x/day and will be going up to 1000 ER 2x/day on Tuesday. I am seeing slight, but steady, decreasing of my numbers. Still they are not where I would like to see them. I do have more weight to lose (20 pounds down in 2 months, another 43 to go) and hopefully that will help, but in the meantime, I am taking the bull by the horns and using every available tool to aid in this. Like princesslinda I saw significantly lower blood sugar numbers after just a few days, but I am SURE that was due to the sudden very low carb diet and sudden introduction of exercise. I am curious to see what the increased dose of the Metformin will do. Metformin has been proven to aid in losing weight so that is an extra bonus for me. Good luck to you and like others have said, I would have a chat with my doctor about possibly upping your Metformin dose as it is very small and it sounds like you have a ways to go to get into a more comfortable neighborhood of blood sugar numbers.
Type 2
6/10/11 A1C = 9.8 FBG = 246
8/10/11 A1C = 6.4
11/18/11 A1c = 5.6 FBG = 101
4/24/12 A1C =5.8 FBG = 109

Metformin 1500 mg. ER /day
HCTZ , Trandalapril , Toprol ER
Vit. D, ALA, EPO, Biotin


"Promise me you'll always remember---you're braver than you believe, and stronger than you seem, and smarter than you think." Christopher Robin to Pooh



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Hi Ranelda and welcome to the forum!

To answer your question: Metformin helped me from the first week I started taking it.
I actually started my diet and exercise before taking Metformin (about 10 days of diet and 3 months of walking) and while diet helped to lower my BG (from 378 not fasting to 200 fasting) and the whole blood works picture (triglycerides, cholesterol, etc) I saw more improvement after starting Metformin.

I actually started the same dose as you 250x2 (I split my pill in half) and did it for a week with an average BG of 156 and after I started a full dose of 500x2 it went down some more right from that first week to about 130 average. Interestingly that first week of full dose I also saw my first few numbers in 80th and even one in 70th! But then they disappeared for about 3 months till 2-3 weeks ago. I have no explanation for this.

In any case after taking Metformin for about 3 months it seems that my BG numbers went down some more as my latest averages are around 105. But I also continue my low carb diet and am trying to exercise when it’s not too hot.

I agree with previous posters that your dose seems a bit too low and while I think it’s OK at the start as some doctors recommend to start low and gradually increase the dose, I think going up a bit would be not a bad idea in some near future. But decision is yours and your doctor’s. Btw when is your next appointment?

Good luck!