The Relationship Of Intramuscular Fat And Glucose Tolerance In Hispanic Women

Abstract

Hispanic Americans are 1.5 times more likely to develop diabetes than non-Hispanic whites of similar age, and in almost every age group, the prevalence is higher in women than in men. Intramuscular fat (IMF) in the thigh has been related to impaired glucose tolerance (IGT) and physical inactivity which are risk factors for type 2 diabetes. PURPOSE: The objective of this pilot study was to determine whether thigh IMF and aerobic fitness are related to glucose tolerance in Hispanic females. METHODS: Participants were 18 Hispanic women (29.4 ± 8.3 years). T1-weighted magnetic resonance images of the right thigh were analyzed for IMF and muscle cross-sectional area (CSA). Peak oxygen uptake (VO2) during cycle ergometry was assessed, and fasting, 30, 60, and 120-minute glucose levels were measured. Differences between participants with (n=6) or without (n=12) IGT were assessed. Independent t-tests and simple linear regression were performed to assess relationships between IMF and the dependent variables. RESULTS: Participants with IGT had 96 % more intramuscular fat CSA (5.7 ± 3.3 vs 2.9 ± 1.5 cm2, P = 0.028) and a higher percentage of IMF (6.8 ± 3.3 vs 3.2 ± 1.5 %, P = 0.005) than non-IGT participants. Peak VO2 was 33% lower for participants with IGT (P = 0.003). Percent IMF was strongly associated with blood glucose levels for fasting (r2 =.34), 30 (r2 =.49), 60 (r2 =.48), and 120- minutes (r2 =.54) following glucose ingestion. Peak VO2 was associated with percent IMF (P = 0.002) and blood glucose at 30, 60, and 120- minutes after glucose ingestion (P < 0.03). CONCLUSIONS: It appears from these preliminary data that fat within the thigh muscle may be associated with impaired glucose tolerance and cardiorespiratory endurance in Hispanic women. Further work is needed to determine the underlying mechanisms behind these relationships.