This photo is from a Bon Appetite article  that describes uses for various vinegars. I don’t see a particular vinegar being used across studies, so maybe any of these will do.

It looks like vinegar’s ability to lower blood glucose isn’t new:

Examination Of The Antiglycemic Properties Of Vinegar In Healthy Adults, Annals of Nutrition and Metabolism, 2010

Results: Two teaspoons of vinegar ( 10 g) effectively reduced postprandial glycemia (PPG), and this effect was most pronounced when vinegar was ingested during mealtime as compared to 5 h before the meal. Vinegar did not alter PPG when ingested with monosaccharides, suggesting that the antiglycemic action of vinegar is related to the digestion of carbohydrates.

Conclusions: The antiglycemic properties of vinegar are evident when small amounts of vinegar are ingested with meals composed of complex carbohydrates. In these situations, vinegar attenuated PPG by 20% compared to placebo.

But how does it do it? One way: It may improve insulin resistance:

The Role Of Acetic Acid On Glucose Uptake And Blood Flow Rates In The Skeletal Muscle In Humans With Impaired Glucose Tolerance, European Journal of Clinical Nutrition, 2015

Conclusions: In individuals with impaired glucose tolerance (IGT), vinegar ingestion before a mixed meal results in an enhancement of muscle blood flow, an improvement of glucose uptake by the forearm muscle and a reduction of postprandial hyperinsulinaemia and hypertriglyceridaemia. From this point of view, vinegar may be considered beneficial for improving insulin resistance and metabolic abnormalities in the atherogenic prediabetic state.

Vinegar Consumption Increases Insulin-Stimulated Glucose Uptake By The Forearm Muscle In Humans With Type 2 Diabetes, Journal of Diabetes Research, 2015

Conclusions: In type 2 diabetes vinegar reduces postprandial hyperglycaemia, hyperinsulinaemia, and hypertriglyceridaemia without affecting lipolysis. Vinegar’s effect on carbohydrate metabolism may be partly accounted for by an increase in glucose uptake, demonstrating an improvement in insulin action in skeletal muscle.

These are all small studies. But the signal is there.