The Digester

A double-blind randomized trial using gold-standard hyperinsulinemic-euglycemic clamps found that adding metformin to insulin for 26 weeks did not reduce insulin resistance in adults with type 1 diabetes, though it reduced insulin dose and raised GDF15, suggesting effects independent of tissue insulin sensitivity.

Metformin did not improve liver, muscle or adipose insulin sensitivity versus placebo after 26 weeks.
Metformin lowered total daily insulin dose by about 0.1 units per kg per day compared with placebo.
Metformin significantly increased serum GDF15 levels relative to placebo.
There was no change in HbA1c, continuous glucose monitoring time-in-range, weight, or arterial stiffness with metformin.
Baseline clamp testing confirmed multi-tissue insulin resistance in adults with type 1 diabetes versus controls.
The single-site trial excluded people with HbA1c above 9.5%, was mostly Caucasian, and may have been underpowered for some secondary outcomes.

Metformin fails to improve insulin resistance in adults with type 1 diabetes in 26-week trial

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