For women it's not age, it's fat (and insulin)

This compelling research published recently in the journal Diabetes discloses that loss of insulin sensitivity (increased insulin resistance) related to increase in adiposity (fat) and, "In contrast, age had no independent effect on insulin sensitivity." Astute readers will recall that insulin resistance is a causal factor in overweight, so the main messages here are: Chronological age and biological age are different (this goes for men too, of course); and life-style behaviors that support healthy insulin regulation are good for a lifetime.