Introducing estimated glomerular filtration rate (eGFR) into clinical practice in the UK: implications for the use of metformin

Diabet Med. 2007 May;24(5):494-7. doi: 10.1111/j.1464-5491.2007.02118.x. Epub 2007 Mar 15.


Aims: The reporting of estimated glomerular filtration rate (eGFR) will identify people with diabetes who have previously undiagnosed renal impairment. Our current guideline recommends discontinuation of metformin when serum creatinine > 150 micromol/l. We examined the implications of replacing this with a criterion based on eGFR.

Methods: The Lothian diabetes register was used to identify patients with Type 2 diabetes for whom age, sex and creatinine measurements within the last 15 months were available. eGFR was calculated using the abbreviated Modification of Diet in Renal Disease (MDRD) equation.

Results: Of 19,981 patients with Type 2 diabetes, 11,297 were taking metformin in accordance with our current guideline. Of these, 9259 (82.0%) had at least stage 2 renal impairment (eGFR < 90 ml/min per 1.73 m(2)) and 2880 (25.5%) had at least stage 3 renal impairment (eGFR < 60 ml/min per 1.73 m(2)). Changing to an eGFR threshold of 36 ml/min per 1.73 m(2) would have a neutral effect on the number of patients eligible for metformin therapy and would permit its use in patients with creatinine concentrations as high as 179 micromol/l. An eGFR threshold of 40 ml/min per 1.73 m(2) would result in 312 (2.8%) patients discontinuing metformin and would permit metformin to be used with creatinine concentrations as high as 163 micromol/l.

Conclusions: The introduction of eGFR reporting could have a major effect on prescription of metformin. A threshold eGFR of 36-40 ml/min per 1.73 m(2) is approximately consistent with our current practice. If our current practice is considered safe, this would be a useful recommendation.

MeSH terms

  • Blood Glucose / analysis
  • Creatinine / blood
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetic Nephropathies / diagnosis*
  • Female
  • Glomerular Filtration Rate / physiology*
  • Humans
  • Kidney Diseases
  • Kidney Function Tests
  • Male
  • Metformin / therapeutic use*
  • Risk Assessment
  • Risk Factors
  • United Kingdom / epidemiology


  • Blood Glucose
  • Metformin
  • Creatinine