Almost a third of Australians with type 1 diabetes also have metabolic syndrome – the ‘double diabetes’ state that puts them at much higher risk of microvascular and macrovascular complications, a study has found.
Data from 2120 people with T1D attending specialist diabetes services across Australia showed that the prevalence of metabolic syndrome was 30% overall and rising with age from 21% in the under-40s to 44% in people over 60.
The biggest contributor to metabolic syndrome was hypertension, which was present in 89% of those with the syndrome but in only 29% of those without, according to the study led by Dr Angela Lee of the Diabetes Centre, Royal Prince Alfred Hospital, Sydney.
Other risk factors such as dyslipidaemia, obesity and microalbuminuria were prevalent in half of the people with metabolic syndrome, but only in a minority in those without.
The study also showed that metabolic syndrome was associated with a two-three fold higher prevalence of microvascular, macrovascular and foot complications compared to people without.
Retinopathy was the most common complication, seen in 60% in T1d patients with metabolic syndrome, compared with 31% in those without. For macrovascular disease, 11% of people with metabolic syndrome had a history of coronary artery bypass grafting or angioplasty, compared with 2.8% in those without metabolic syndrome.
The increased risk of complications with metabolic syndrome was highest in younger people. For macrovascular complications, the odd ratio associated with metabolic syndrome was 5.9 in people under 40 years, 2.7 in those aged 40–60 years, and 1.7 in people over 60.
The associations were still evident when they omitted microalbuminuria as a confounding factor, as this might be associated with antihypertensive treatment.
Metformin use was also more common among people with metabolic syndrome ( 16%) compared to those without (3.6%) – and users had a more unfavourable cardiometabolic profile in terms of obesity, blood pressure and lipids.
Writing in Diabetic Medicine, the study authors said the rates of metabolic syndrome in people with T1D were similar to those seen in the general population, but conferred the additional risks of a ‘double diabetes’ state of insulin deficiency and insulin resistance.
They said it was notable that the greatest association with risk of complications was seen in young to middle aged people with T1D and metabolic syndrome, suggesting it could be used to identify people for early intervention with more intensive risk factor control.
“This double diabetes phenotype may be clinically important for identifying a high-risk population that requires aggressive management of cardiovascular risk factors and the potential use of non-insulin adjunctive diabetes therapies that have so far been used primarily in type 2 diabetes to reduce diabetes complications,” they concluded.