<a><b>OBJECTIVE
</b>Disruption of rest-activity rhythms is cross-sectionally associated with
metabolic disorders, including type 2 diabetes (T2D), yet it remains unclear whether
it predicts impaired glucose metabolism and homeostasis.
The aim of this study is to examine the cross-sectional and prospective
associations between rest-activity rhythm characteristics and glycemic measures
in a cohort of older men.</a>
<p><b>RESEARCH DESIGN AND METHODS</b> Baseline rest-activity rhythms were derived from actigraphy using
extended cosine model analysis. Fasting glucose, insulin and
<a>homeostasis
model assessment of insulin resistance </a>(HOMA-IR) were measured from fasting blood at
baseline and after ~3.5 years. T2D were defined using self-report, medication
use and fasting glucose. </p>
<p> <b>RESULTS</b> In the cross-sectional analysis (n=2,450), lower 24-hour amplitude:mesor ratio (i.e.,
mean-activity-adjusted rhythm amplitude) and reduced overall rhythmicity, were
associated with higher fasting insulin and HOMA-IR (all <i>p-trend < 0.0001</i>), indicating increased insulin resistance. The
odds of baseline T2D were significantly higher among those in the lowest
quintile of amplitude (OR <sub>Q1 vs Q4</sub> (95% CI), 1.63 (1.14, 2.30)) and
late acrophase group (OR <sub>late vs normal</sub> (95% CI), 1.46
(1.04, 2.04)). In the prospective analysis (n=861), multiple rest-activity
characteristics predicted a 2-3 fold increase in T2D risk, including a lower
amplitude (OR <sub>Q1 vs Q4</sub> (95% CI), 3.81 (1.45, 10.00)) and
amplitude:mesor ratio (2.79
(1.10, 7.07), reduced overall rhythmicity (3.49 (1.34, 9.10)), and a
late acrophase (2.44
(1.09, 5.47)).</p>
<p><b>CONCLUSIONS</b> Rest-activity
rhythm characteristics are associated with impaired glycemic metabolism and
homeostasis and higher risk of incident T2D.<br>
</p>