Researchers from King’s College London and the University of Manchester found that testing for glucose levels means patients are being diagnosed with type 2 diabetes too late, as their blood vessels may already have been damaged from impaired metabolism of fat in the blood.
The definition of 'diabetes' should be changed to account for the fact that outcomes of the disease can be observed before it causes glucose levels to rise, they said.
The study, published in the PLOS ONE journal, focused on 100 young women from Greater Manchester who had previously been pregnant. They were separated into groups based on their blood glucose levels during their pregnancy, which ranged from normal to overt gestational diabetes.
As gestational diabetes increases susceptibility to the later development of type 2 diabetes, the women were categorised as being at increased, intermediate or low risk of developing type 2 diabetes.
Follow-up tests were conducted at an average of 22 months after their pregnancy. The researchers found that women in the higher-risk groups had lower levels of fat metabolites in their blood, even though their blood glucose levels were still considered normal.
According to the findings, these metabolic defects were causing damage to blood vessels and certain pancreatic cells in the affected patients.
‘The data here clearly point to early alteration in lipoprotein metabolism in the chain of events that culminate in diabetes and its complications,’ the researchers said.
Type 2 diabetes is currently defined by hyperglycaemia. Current methods of diagnosing the disease involve testing the glucose levels in a patient’s blood.
But given that negative effects from the disease can be observed before blood glucose levels rise, researchers said the result indicated that a ‘new, quite different’ definition of type 2 diabetes was required, before the condition could ‘deteriorate’ to that state.
They said this new definition should ‘incorporate disturbed lipid metabolism’ as an early indicator of the disease.
Professor Kennedy Cruickshank, lead author of the study, said: ‘The current method of categorising type-2 diabetes solely by a patient's glucose level means that many will already have suffered blood vessel damage and will experience poorer outcomes.
‘Our study overall adds weight to the argument that type-2 diabetes should not be classified as 'diabetes' as we currently understand it from just measuring blood glucose.’