Cardiac energy metabolism is decreased in male volunteers with prediabetes and does not normalize during the day

TL;DR

Men with prediabetes have lower heart energy levels in the morning compared to healthy individuals, and these levels don't change by evening.

Contribution

This study is the first to show decreased cardiac energy metabolism in prediabetic men, independent of time of day or free fatty acids.

Findings

Prediabetic men had lower PCr/ATP ratios compared to non-insulin resistant individuals.

No significant differences in free fatty acids or cardiac function were observed between groups.

Cardiac energy status remained unchanged from morning to evening in prediabetic volunteers.

Abstract

Type 2 diabetes mellitus is characterized by a low cardiac energy status (PCr/ATP ratio), but it is unknown whether this also applies to prediabetes. Since PCr/ATP is correlated with elevated free fatty acids (FFA), a potentially lower PCr/ATP might be secondary to elevated FFA. To investigate this, we determined PCr/ATP and FFA levels in volunteers with prediabetes at two time‐points during the day. Eight male volunteers with prediabetes underwent a MRI/MRS scan to determine left ventricular ejection fraction (LVEF) and PCr/ATP ratio at 7 am and at 5 pm. For reference, these results were compared to eight non‐insulin resistant overweight or obese volunteers. Myocardial energy status was lower in the volunteers with prediabetes (PCr/ATP 1.03 ± 0.08) compared to non‐insulin resistant overweight or obese volunteers (PCr/ATP 1.22 ± 0.04, p < 0.05), but FFA were not significantly different between groups. LVEF was similar in the volunteers with prediabetes compared to healthy overweight and obese volunteers (p = 0.23). Volunteers with prediabetes have a lower myocardial energy status in the morning compared to healthy overweight and obese volunteers, while cardiac function remained normal. In addition, no differences between morning and evening measurements of cardiac energy status and function were found.

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