Lifestyle prevention of diabetes may halve carbon footprint associated with treating complications

Preventing high blood glucose (pre-diabetes) from turning into type 2 diabetes with lifestyle changes could more than halve the carbon footprint associated with treating the complications of the disease, suggests a modelling study, published in the open access journal BMJ Open.

And effective management of the disease could cut greenhouse gas emissions by 21%, the calculations indicate.

In 2021, 537 million adults around the globe were living with diabetes, a number that is expected to rise to 783 million by 2045, 4.41 million of whom will be in the UK, note the researchers. 

Diabetes and/or its complications killed around 6.7 million people globally in 2021-140,000 of them in the UK. And the total NHS costs of the disease added up to £14 billion in 2021-2, they add.

Yet despite evidence-based clinical guidance, more than 1 in 3 of those living with type 2 diabetes in England (36%) and Wales (39%) fail to achieve the target glycosylated haemoglobin (HbA1c) level of 7.5% (58 mmol/mol), they point out.

While previously published research has detailed the financial cost and health benefits of treatment, few studies have assessed the environmental impact, measured in greenhouse gas emissions, of which CO2 makes up around 75%, they explain.

In 2019, the annual carbon footprint of the NHS in England was about 25 megatons of CO2 equivalent (CO2e), around 4% of total national greenhouse gas emissions. And the NHS has committed to achieving net zero emissions by 2040, with an ambition for an 80% reduction by 2028-32.

In support of this goal, the researchers wanted to gauge the environmental impact of preventing pre-diabetes progression and effective management of type 2 diabetes once established.

They incorporated an environmental module into existing IQVIA data analytics on diabetes to estimate the impact of improving clinical outcomes on greenhouse gas emissions over a lifetime.

They assessed two hypothetical scenarios: (1) preventing progression from pre-diabetes through diet and exercise in people aged over 40 compared with no intervention and natural subsequent progression to type 2 diabetes; and (2) well controlled diabetes with medicines compared with poorly controlled disease in people aged 54+.

Greenhouse gas emissions associated with type 2 diabetes were estimated based on the avoidance of ongoing drug treatment; anticipated cardiovascular, renal, and eye complications in the absence of appropriate interventions; and the procedures, medication, and travel components involved.

Their analysis showed that stopping pre-diabetes from turning into type 2 diabetes would result in an extra 6 years of life over a lifetime compared with natural progression. 

People who remained pre-diabetic had much lower lifetime complication rates (244 vs 60,167 events/100 patients) than those whose disease evolved naturally, especially renal (73% fewer events) and eye disease (59% fewer events).

The cumulative incidence of cardiovascular complications, however, was slightly higher in those who remained pre-diabetic (11% more cumulative events), mainly because the risks of heart disease rise in older age, even in the absence of pre-diabetes, say the researchers. 

The total amount of greenhouse gas emissions associated with the care of people with pre-diabetes and no subsequent progression was 67% less (19,129 kg CO2 over a lifetime) than those who naturally progressed, the analysis indicated. 

This was primarily driven by less need for the treatment of complications: cardiovascular disease (36%); renal disease (98%); and eye disease (73%) as well as no need for drug treatment of type 2 diabetes (88.5% decrease).

And well controlled type 2 diabetes would add nearly 2 extra years of life and cut CO2 e emissions by 21% compared with uncontrolled disease: 14,545 kg CO2e over 23 years vs 18,516 kg CO2e over 21 years, respectively, even after a 2-5 year treatment delay. 

Again, the savings were primarily driven by the avoidance of treating type 2 diabetes complications.

The researchers acknowledge various limitations to their findings, including the overall lack of tried and tested methodologies to determine greenhouse gas emissions associated with various therapeutics and the management of complications, particularly expensive resource intensive procedures.

Nor were they able to capture the reduced carbon footprint of adopting a healthier lifestyle among those with pre-diabetes, as these data aren't available.

"While health economic modelling techniques are employed to evaluate the environmental impact of [type 2 diabetes] management, this study does not constitute a conventional economic evaluation, as healthcare costs are not included as an outcome," they point out.

Nevertheless, they conclude: "This study underscores that (1) effective prevention of [type 2 diabetes] through diet and exercise in adults with pre-diabetes, and (2) optimal disease management in adults with [type 2 diabetes] through early implementation of evidence- based recommendations, can improve patient outcomes and reduce the healthcare-related environmental impact. 

"Reductions in the incidence of comorbidities (especially cardiovascular and renal events) are key to driving savings in [greenhouse gas] emissions."