Metformin, a cheap century-old drug, cut insulin use by 12 per cent in adults with type 1 diabetes, a recent Australian study has found.
A randomised trial in 40 adults with long-term type 1 diabetes found insulin doses were 12 per cent lower with metformin over six months, with no change in blood sugar control.
The team had expected metformin to improve insulin resistance, as in type 2 diabetes, but instead saw lower insulin needs without changes in insulin resistance.
Researchers at the Garvan Institute of Medical Research, who describe this as the first randomised controlled trial of its kind, ran the six-month study.
Dr Jennifer Snaith, study co-leader at Garvan, said: “Insulin resistance is a growing problem in type 1 diabetes.
“Not only does it make regulating blood sugar levels difficult, but it is an underappreciated risk factor for heart disease, which is one of the biggest causes of health complications and deaths in those with type 1 diabetes.”
The researchers randomised 40 adults with long-term type 1 diabetes to take either metformin or a placebo for six months.
They examined whether their insulin resistance changed over that time through a sophisticated and comprehensive research technique, called a clamp study, that allowed the team to map insulin resistance in different parts of the body.
A clamp study is a precise test that measures how well the body responds to insulin by controlling blood sugar and insulin levels while monitoring glucose uptake in different tissues.
Dr Snaith said: “Although we didn’t find changes to insulin resistance from the use of metformin, we did show that people taking it used around 12 per cent less insulin than those on placebo.
“This is an important result.
“Insulin is a relatively old treatment which, while lifesaving, comes with significant mental and physical burden.
“This means that lowering the amount of insulin used is a priority for many people living with type 1 diabetes. We have shown that a very cheap, accessible medication may serve this purpose and this is very exciting.”
The team is now investigating how metformin reduces insulin needs in type 1 diabetes.
If confirmed, this could mean fewer injections, lower costs and a lower risk of hypoglycaemia, and may also help limit weight gain linked to high insulin doses.