# Association between hyperglycaemia, diabetes complications and development of fibrotic conditions among people living with type 1 and type 2 diabetes in England: a retrospective cohort study using UK Clinical Resource Datalink Aurum and Hospital Episode Statistics

## TL;DR

This study explores how high blood sugar and diabetes complications are linked to fibrotic diseases in people with type 1 and type 2 diabetes in England.

## Contribution

The study identifies specific associations between diabetes complications and fibrotic conditions in both type 1 and type 2 diabetes populations.

## Key findings

- In type 1 diabetes, albuminuria was associated with lung fibrosis and microvascular complications with atherosclerosis and cardiomyopathy.
- In type 2 diabetes, both high blood sugar and diabetes complications were linked to most fibrotic conditions.
- No consistent association was found between diabetes status and all fibrotic diseases in type 1 diabetes.

## Abstract

Fibrosis is a pathological feature that can occur in a wide range of diseases including diabetes mellitus. We investigated whether in people with type 1 (T1DM) or type 2 diabetes mellitus (T2DM), glycaemia or diabetes-related complications are associated with fibrotic diseases.

Retrospective cohort study using UK Clinical Resource Datalink (CPRD) Aurum and Hospital Episode Statistics.

We included people with prevalent T1DM or T2DM as of 31 December 2015 (recorded in CPRD Aurum), eligible for linkage with Hospital Episode Statistics and followed up for 3 years.

We defined diabetes status using blood/urine biomarkers and complications. In the T2DM cohort, we also investigated exposures of hyperglycaemia, insulin resistance and metformin prescription. Fibrotic condition diagnoses were determined from both primary and secondary care records. Logistic regression analyses were undertaken to understand the strength of association between diabetes status/diabetic complications and fibrotic conditions, respectively.

The T1DM cohort consisted of 9669 people while the T2DM cohort included 504 066 people. In T1DM, we found that albuminuria was associated with lung fibrosis (ORadj: 2.07, 99% CI 1.35 to 2.17), and microvascular complications were associated with atherosclerosis (ORadj: 1.81, 99% CI 1.18 to 2.77) and cardiomyopathy (ORadj 1.53, 99% CI:1.15 to 2.04). In the T2DM cohort, both glycaemia above target and diabetes complications were associated with most fibrotic conditions.

Within the T1DM population, no consistent association between diabetes status and all fibrotic diseases was observed. More research is required to understand whether the association between diabetes complications and fibrotic diseases is due to shared risk factors or whether glycaemia in T2DM may be influenced by fibrotic pathology.