Diabetes is a chronic disease characterised by high blood glucose levels. Monitoring of blood glucose plays an important role in the management of diabetes. Although, several different glycaemic measures are used in clinical practice, glycated haemoglobin (HbA1c) is increasingly accepted as the standard on which many clinical decisions are based. In this thesis, the relationship between HbA1c and different blood glucose measures will be examined and their relevance to diabetic complications will be investigated. This work is for people at increased risk of type 2 diabetes and for those with newly diagnosed type 2 diabetes. Using the blood glucose profiles available from continuous glucose monitoring, the relationships between HbA1c and derived blood glucose measures were studied. Mean blood glucose and blood glucose peaks equally predicted HbA1c. The correlation of FPG to HbA1c was weaker than that of mean blood glucose. The haemoglobin glycation index (HGI) is defined as the difference between a subject's HbA1c and that expected from regression of HbA1c on FPG and captures the variation in HbA1c not attributable to FPG. I used Early Diabetes Intervention Trial (EDIT) and UK prospective diabetes study (UKPDS) data to determine whether HGI is reproducible and whether differences relate to potential confounders. In both studies, HGI was reproducible and not explained by the potential confounders examined. I examined whether there were additive effects of FPG, HbA1c or HGI on diabetic complications using UKPDS data since it was found previously that either HbAlc or FPG was related to diabetic complications in UKPDS. For microvascular complications, both FPG and HbA1c were independent risk factors. When HGI was related to microvascular complications, HGI made an independent contribution adjusting for either FPG or HbA1c. For macrovascular complications, HbA1c but not FPG was an independent risk factor. HGI did not make an independent contribution to macrovascular complications adjusting for HbA1c. My work showed that the same HbA1c level does not necessarily have the same clinical meaning in two different subjects. There can be marked differences in individual levels of HbA1c relative to FPG values in people with type 2 diabetes. Thus, HbA1c levels should be interpreted with caution and treatment decisions need to be made considering individual glycaemic control. HGI may be useful, informing healthcare professionals of the likely magnitude and direction of difference between observed HbA1c levels and those expected in the light of prevailing blood glucose levels.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:437360 |
| Date | January 2006 |
| Creators | Kim, Ji-in |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://ora.ox.ac.uk/objects/uuid:1004b345-fca6-4516-9f5c-b1c20cba72ee |
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