Are insulin resistance, impaired fasting glucose and impaired glucose tolerance all equally strongly related to age?

Background: Insulin resistance (IR) has been considered an underlying cause of impaired glucose tolerance (IGT) and impaired fasting glucose (IFG). Whether IR increases with age has been debated. We investigated the age-associated deterioration in the homeostasis model assessment (HOMA) of IR and in glucose metabolism.

Methods: Ten (nine including women) European studies contributed data on 6314 men and 6393 women aged 30-88 years. The cohort- and sex-specific top 25% of HOMA of IR in non-diabetic subjects was used to define HOMA-IR.

Results: Compared with subjects aged 50-59 years, the cohort- and body mass index-adjusted odds ratio (95% confidence interval) for HOMA-IR was 0.83 (0.64, 1.08), 0.87 (0.74, 1.03), 1.20 (1.02, 1.42) and 1.45 (1.10, 1.92) in men and 0.84 (0.62, 1.14), 0.91 (0.77, 1.09), 1.38 (1.19, 1.62) and 1.71 (1.35, 2.17) in women, respectively, aged 30-39, 40-49, 60-69 and > or = 70 years (P < 0.0001 for trend test). The same increasing trend was also observed for IFG. In contrast, the corresponding odds ratios for IGT increased linearly and more strongly with age, being 0.37 (0.22, 0.63), 0.67 (0.52, 0.87), 1.55 (1.24, 1.92) and 2.96 (2.13, 4.13) in men and 0.51 (0.31, 0.85), 0.66 (0.52, 0.86), 1.92 (1.57, 2.35) and 3.85 (2.89, 5.12) in women, respectively.

Conclusions: Age is more strongly associated with IGT than with HOMA-IR or IFG in non-diabetic European populations.