Absolute agreement.
I have noticed when we get threads about Metformin, it is usually people who have had bad experiences of the drug who are the most vocal. Which might give the impression that most people have problems with it. I do not think this is the case.
I have also noticed that posters have started making statements such as 'Metformin won't affect your blood glucose'.
This is incorrect, and when I see this stated, I have started giving some accurate information on the effectiveness of the drug. Many people worldwide find it invaluble to control their type 2, and it would be tragic if those people's health was negatively affected by a vocal minority who get contraindications from Metformin.
Regarding the effectiveness of Metformin in lowering blood glucose.
This meta study
http://care.diabetesjournals.org/content/35/2/446
showed
A total of 35 trials were identified for the main analysis and 7 for the dose-comparison analysis. Metformin monotherapy lowered HbA1c by 1.12% (95% CI 0.92–1.32; I2 = 80%) versus placebo, metformin added to oral therapy lowered HbA1c by 0.95% (0.77–1.13; I2 = 77%) versus placebo added to oral therapy
monotherapy is when only one drug is used
In case anyone is wondering, the 1.12% figure mentioned is the % shown at the top of the arc (image below) equates to approx 11 mmol/mol (as used in UK HbA1c results).
As a real life example, that means someones HbA1c would lower from 70 to 59 mmol/mol on the chart below
Another way of looking at it, is to understand that those same people would see each of their home finger prick tests drop by an average of 1.5mmol/l
(depending on dose and individual physiology, of course)
I am not going to pretend that Metformin doesn't cause contraindications, some of which are very unpleasant. No drug suits everyone. And no one should continue to take a drug that disagrees with them. However I don't feel it is approriate to state that Metformin in ineffective at lowering blood glucose, when the trials exist proving otherwise.
Regarding Metformin causing B12 deficiency.
Yes, it is proven that long term (months or years) of Metformin use may cause progressive B12 deficiency in some, but not all patients.
https://www.bmj.com/content/340/bmj.c2181
Since Metformin acts to reduce B12 absorption in the gut, it is possible to supplement with sublingual B12 or have supplements by injection on prescription.
The quoted study suggests that all patients prescribed Metformin longterm should be given periodic tests for B12 deficiency.
Anyone not offered these tests can ask for them from their doctor.
This seems very sensible, and I would encourage anyone to supplement with B12 if they feel concerned.
It is always going to be up to the patient, and their doctor, to weigh up the risks and benefits of any drug treatment, and make informed decisions. Once again, I personally prefer that those decisions are based on evidence from scientific studies. Then I use personal experience of taking the drug to decide whether it will suit me personally.