Subclinical lipohypertrophy——Easily ignored complications of insulin therapy

•Subclinical lipohypertrophy is common among insulin-injecting patients with diabetes and is associated with poor glycemic control.•Type 1 diabetes, increasing BMI, incorrect rotation of sites and insulin needle reusage for more than four times have been identified as the risk factors for subclinical lipohypertrophy.•Ultrasonography may be an ideal adjunct in evaluation of easily ignored lipohypertrophy, especially where poor glycemic control, incorrect injection behaviors, overweight or obesity are documented.