A large observational analysis of 23,475 US adults (NHANES 2009–2023) suggests the optimal nightly sleep duration for lowering risk of insulin resistance — a precursor to type 2 diabetes — is about 7 hours 18 minutes. Researchers, led from Nantong University in China and publishing in BMJ Open Diabetes Research & Care, used estimated glucose disposal rate (eGDR), derived from waist circumference, fasting glucose and blood pressure, as the primary outcome. They found an inverted U‑shaped association between weekday sleep length and eGDR: both shorter and longer sleep than the 7h18m “sweet spot” were linked with worse metabolic markers. Analysis of weekend “catch‑up” sleep in 10,817 participants showed benefit for those with weekday sleep debt (one to two hours of extra weekend sleep) but potential harm for people already sleeping at or above the optimal duration who added more than two hours at weekends. The study was observational and based on self‑reported sleep, so it cannot prove causation; authors call for further mechanistic and interventional research.