Technetium-99m sestamibi retention in skeletal muscles, a potential indicator of mitochondrial function and anaerobic threshold in patients with type 2 diabetes

Abstract

In this study, we investigated the retention of technetium-99m sestamibi (MIBI), a radiopharmaceutical that accumulates in mitochondria, in patients with type 2 diabetes. We hypothesized that patients with type 2 diabetes had lower MIBI counts in their legs than non-diabetic volunteers, and that these abnormalities reflected a low anaerobic threshold (AT) during cardiopulmonary exercise testing (CPX). Eight non-diabetic volunteers (Group N) and 11 patients with type 2 diabetes (Group D) underwent CPX. Mitochondrial function was assessed using MIBI imaging of both legs. The MIBI counts in the legs were significantly lower in Group D than in Group N (D vs. N: 74.1 vs. 94.1 counts/pixel, p < 0.05). Similarly, peak oxygen uptake (peakVO2) and AT were lower in Group D than in Group N (peakVO2: 19.8 vs. 26.5 ml/kg/min, p < 0.05; AT: 13.1 vs. 17.2 ml/kg/min, p < 0.05). A strong correlation was observed between MIBI counts and the peakVO2 and AT (peakVO2: r = 0.62, p < 0.01; AT: r = 0.76, p < 0.01). After the exclusion of an outlying subject, the correlation between peakVO2 and MIBI count in the legs was lost (r = 0.28, p = 0.26); however, the AT correlation was maintained (r = 0.59, p = 0.01). Patients with type 2 diabetes had reduced skeletal muscle MIBI counts, indicating reduced mitochondrial function. This abnormality may be linked to a low AT.

Keywords

• type 2 diabetes
• mitochondrial function
• cardiopulmonary exercise testing
• anaerobic threshold