ABNORMALITY OF MYOCARDIAL OXIDATIVE-METABOLISM IN NONINSULIN-DEPENDENT DIABETES-MELLITUS

The purpose of this study was to evaluate oxidative metabolism and its response by dobutamine in patients with noninsulin-dependent diabetes mellitus (NIDDM) using C-11-acetate PET. Methods: We studied 16 patie nts with NIDDM (9 men, 7 women; mean age 53.7 +/- 12.8 yr) and 6 healt hy male control subjects (mean age 41.8 +/- 17.2 yr). None of them had an abnormality on stress-perfusion SPECT. The C-11-acetate clearances (Kmono) were compared regionally for five myocardial segments in all subjects at rest and during low-dose dobutamine stress in 13 patients (8 patients with NIDDM, age 51.9 +/- 13.6 yr; 5 healthy male control s ubjects, age 45.6 +/- 16.3 yr), Correlation between regional Kmono and rate-pressure product (RPP) was also studied. Results: At rest, the c learance of C-11-acetate was slightly heterogeneous for both patients with NIDDM and healthy control subjects, with smaller values in the ap ex and inferior wall in both groups. The difference became significant during dobutamine stress in the patients. The RPP-to-Kmono (average f or five segments) ratio at rest was slightly smaller in the patients ( 1042.7 +/- 559.1 x 0.01) than in the healthy control subjects (1391.4 +/- 209.6 x 0.01, not significant), and those during debut amine stres s were almost the same in the two groups (1457.3 +/- 737.4 x 0.01 and 1486.0 +/- 211.8 x 0.01, respectively). A significant correlation was seen between regional Kmono and RPP in every segment in the healthy co ntrol subjects (average; r = 0.89; p < 0.01), whereas more scattered c orrelation with greater regional variation was observed in the patient s (average; r = 0.31; p value was not significant). Conclusion: Patien ts with NIDDM showed slight regional heterogeneity in myocardial oxida tive metabolism. They also had more scattered correlation between myoc ardial oxidative metabolism and cardiac work (RPP) than healthy contro l subjects, with the smallest correlation coefficient observed in the inferior wall. These findings may help the understanding of dynamics i n myocardial oxidative metabolism of NIDDM hearts.