Background

A family history of type 2 diabetes (FH) is linked with impaired insulin sensitivity (IS) and metabolic flexibility (MF). It is unknown whether a FH reduces the ability to improve IS and MF with exercise. The purpose of this study was to determine whether IS and MF are impaired in healthy individuals with a FH and whether improvements in IS and MF are attenuated with 8 weeks of combined exercise training compared with individuals without a FH.

Methods

19 sedentary, normoglycemic, Mexican-American men with (FH+, n=10) and without (FH-, n=9) a FH underwent 8 weeks of combined exercise training (3x/week aerobic & resistance). A 5-day standardized diet (55/15/30% CHO/PRO/FAT) was provided before pre and post intervention tests. IS was assessed via hyperinsulinemic euglycemic clamp. MF was calculated as the change in respiratory quotient (RQ) at the insulin-stimulated state of the clamp compared to the fasted state (ΔRQ). Statistical analysis was performed using GraphPad Prism 7.0.

Results

There were no differences in IS, MF, VO2max, and body composition between normoglycemic men with or without a FH (p>0.05 for all parameters). IS improved after 8 weeks of combined exercise training in both groups (FH- 2.99 ± 0.27 to 3.89 ± 0.28 ml/kg estimated metabolic body size (EMBS), p=0.02; FH+ 3.63 ± 0.50 to 4.82 ± 0.51 ml/kg EMBS; p=0.002). MF did not change in either group (FH-, 0.07 ± 0.01 to 0.09 ± 0.01, p=0.71; FH+ 0.08 ± 0.01 to 0.11 ± 0.02; p=0.24). Following 8 weeks of combined exercise training, there were significant improvements in VO₂max, lean mass, upper- and lower-body strength regardless of FH (p<0.05).

Conclusions

FH+ did not impair metabolic flexibility, insulin sensitivity, aerobic fitness, and strength in a sedentary, normoglycemic population. FH+ is not a limiting factor for exercise induced improvements in metabolic flexibility, insulin sensitivity, aerobic fitness, body composition, and strength in young normoglycemic Mexican-American men.