Defining the relationship between average glucose and HbA1c in patients with type 2 diabetes and chronic kidney disease

Diabetes Res Clin Pract. 2014 Apr;104(1):84-91. doi: 10.1016/j.diabres.2014.01.020. Epub 2014 Feb 3.

Abstract

Aims: To examine the relationship between average glucose (AG) and HbA1c in patients with and without chronic kidney disease (CKD) and type 2 diabetes.

Materials and methods: 43 patients with diabetes and CKD (stages 3-5) with stable glycaemic control, and glucose-lowering and erythropoiesis stimulating agent (ESA) doses, were prospectively studied for 3 months and compared to 104 age-matched controls with diabetes, without CKD from the ADAG study. Over 3 months, AG was calculated from 7 to 8 point self-monitored blood glucose measurements (SMBG) and from continuous glucose monitoring (CGMS), and mean HbA1c was calculated from 4 measurements. AG and HbA1c relationships were determined using multivariable linear regression analyses.

Results: The CKD and non-CKD groups were well matched for age and gender. Mean AG tended to be higher (p=0.08) but HbA1c levels were similar (p=0.68) in the CKD compared with non-CKD groups. A linear relationship between AG and HbA1c was observed irrespective of the presence and stage of CKD. The relationship was weaker in patients with stage 4-5 CKD (non-CKD R2=0.75, stage 3 CKD R2=0.79 and stage 4-5 CKD R2=0.34, all p<0.01). The inclusion of ESA use in the model rendered the effect of CKD stage insignificant (R2=0.67, p<0.01).

Conclusions: In patients with type 2 diabetes and CKD there is a linear relationship between HbA1c and AG that is attenuated by ESA use, suggesting that ESA results in a systematic underestimation of AG derived from HbA1c.

Keywords: Chronic kidney disease; Diabetes mellitus; Erythropoietin stimulating agent; Glycated haemoglobin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers / blood
  • Blood Glucose / metabolism*
  • Blood Glucose Self-Monitoring / methods*
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / complications
  • Female
  • Follow-Up Studies
  • Glycated Hemoglobin A / metabolism*
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Renal Insufficiency, Chronic / blood*
  • Renal Insufficiency, Chronic / complications
  • Young Adult

Substances

  • Biomarkers
  • Blood Glucose
  • Glycated Hemoglobin A
  • hemoglobin A1c protein, human