Are the metabolic benefits of resistance training in type 2 diabetes linked to improvements in adipose tissue microvascular blood flow?

The microcirculation in adipose tissue is markedly impaired in type 2 diabetes (T2D). Resistance training (RT) often increases muscle mass and promotes a favourable metabolic profile in people with T2D, even in the absence of fat loss. Whether the metabolic benefits of RT in T2D are linked to improvements in adipose tissue microvascular blood flow is unknown. Eighteen sedentary people with T2D (7F/11M, 52±7 years) completed six weeks of RT. Before and after RT, overnight-fasted participants had blood sampled for clinical chemistries (glucose, insulin, lipids, HbA1c and pro-inflammatory markers), underwent an oral glucose challenge (OGC, 50g glucose x 2hr) and a DEXA scan to assess body composition. Adipose tissue microvascular blood volume and flow were assessed at rest and 1hr post-OGC using contrast-enhanced ultrasound. RT significantly reduced fasting blood glucose (p=0.006), HbA1c (p=0.007), 2-hr glucose area under the time curve post-OGC (p=0.014) and HOMA-IR (p=0.005). This was accompanied by a small reduction in total body fat (p=0.002), trunk fat (p=0.023) and fasting triglyceride levels (p=0.029). Lean mass (p=0.003), circulating TNFa (p=0.006) and soluble VCAM-1 (p<0.001) increased post-RT. There were no significant changes in adipose tissue microvascular blood volume of flow following RT, however those who did have a higher baseline MBF post-RT also had lower fasting triglyceride levels (r=-0.476, p=0.045). The anthropometric, glycemic and insulin sensitizing benefits of six weeks of RT in people with T2D are not associated with an improvement in adipose tissue microvascular responses, however there may be an adipose tissue microvascular-linked benefit to fasting triglyceride levels.