I think you have to read the whole paragraph:
The degree of hyperglycaemia was strongly associated with risk of death related to COVID-19 after adjusting for other risk factors. For people with Type 2 diabetes, those with an HbA1c of 59-74 mmol/mol had a hazard ratio of 1·23 (95% CI 1·15 – 1·32) compared with people with an HbA1c of 48-53mmol/mol. In people with Type 2 diabetes and an HbA1c of ≥86mmol/mol the HR was 1·62 (95% CI 1·48-1·79). A similar overall pattern of association was seenin people with Type 1 diabetes, but the raised risk was only statisticallysignificant in those with an HbA1c ≥ 86 mmol/mol (HR 2·19 95% CI 1·46-3·29) when compared to those with a HbA1c of 48-53 mmol/mol. The hazard ratio in people with Type 2 diabetes and a low HbA1c ( <48mmol/mol) was 1·11 (95% CI 1·04 – 1·18) and a similar, but non-statistically significant risk was seen in the equivalent glycaemic control group in people with Type 1 diabetes (HR 1·22 95% CI 0·78 – 1·91).
So they’re comparing in this section the relative risk of dying among diabetics…so what they’re saying here is that on average, having a lower A1C was protective for T1Ds but that this effect only reached statistical significance when you compared people in the lowest A1C group with those in the highest A1C group, which means in essence that A1C is not as clearly protective in this group as it is in the T2s. That could be because A1C is less of a definitive factor for T1s, or it could be because fewer people died overall, so this group is sort of underpowered to see a difference.
But correct me if I am reading it wrong…