Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults.

AIMS/HYPOTHESIS: The aim of this study was to compare exercise capacity, strength and skeletal muscle perfusion during exercise, and oxidative capacity between South Asians, African Caribbeans and Europeans, and determine what effect ethnic differences in the prevalence of type 2 diabetes has on these functional outcomes. METHODS: In total, 708 participants (aged [mean±SD] 73 ± 7 years, 56% male) were recruited from the Southall and Brent Revisited (SABRE) study, a UK population-based cohort comprised of Europeans (n = 311) and South Asian (n = 232) and African Caribbean (n = 165) migrants. Measurements of exercise capacity using a 6 min stepper test (6MST), including measurement of oxygen consumption ([Formula: see text]) and grip strength, were performed. Skeletal muscle was assessed using near infrared spectroscopy (NIRS); measures included changes in tissue saturation index (∆TSI%) with exercise and oxidative capacity (muscle oxygen consumption recovery, represented by a time constant [τ]). Analysis was by multiple linear regression. RESULTS: When adjusted for age and sex, in South Asians and African Caribbeans, exercise capacity was reduced compared with Europeans ([Formula: see text] [ml min-1 kg-1]: ß = -1.2 [95% CI -1.9, -0.4], p = 0.002, and ß -1.7 [95% CI -2.5, -0.8], p < 0.001, respectively). South Asians had lower and African Caribbeans had higher strength compared with Europeans (strength [kPa]: ß = -9 [95% CI -12, -6), p < 0.001, and ß = 6 [95% CI 3, 9], p < 0.001, respectively). South Asians had greater decreases in TSI% and longer τ compared with Europeans (∆TSI% [%]: ß = -0.9 [95% CI -1.7, -0.1), p = 0.024; τ [s]: ß = 11 [95% CI 3, 18], p = 0.006). Ethnic differences in [Formula: see text] and grip strength remained despite adjustment for type 2 diabetes or HbA1c (and fat-free mass for grip strength). However, the differences between Europeans and South Asians were no longer statistically significant after adjustment for other possible mediators or confounders (including physical activity, waist-to-hip ratio, cardiovascular disease or hypertension, smoking, haemoglobin levels or ß-blocker use). The difference in ∆TSI% between Europeans and South Asians was marginally attenuated after adjustment for type 2 diabetes or HbA1c and was also no longer statistically significant after adjusting for other confounders; however, τ remained significantly longer in South Asians vs Europeans despite adjustment for all confounders. CONCLUSIONS/INTERPRETATION: Reduced exercise capacity in South Asians and African Caribbeans is unexplained by higher rates of type 2 diabetes. Poorer exercise tolerance in these populations, and impaired muscle function and perfusion in South Asians, may contribute to the higher morbidity burden of UK ethnic minority groups in older age.

African Caribbeans have greater subclinical cerebrovascular disease than Europeans: this is associated with both their elevated resting and ambulatory blood pressure and their hyperglycaemia.

OBJECTIVES: Stroke is elevated in people of black African descent, but evidence for excess subclinical cerebrovascular disease is conflicting, and the role of risk factors in determining any ethnic differences observed unexplored. METHODS: We compared prevalence of brain infarcts, and severe white matter hyperintensities (WMHs) on cerebral MRI, in a community-based sample of men and women aged 58-86 of African Caribbean (214) and European (605) descent, in London, UK. Resting, central and ambulatory blood pressure (BP) were measured; diabetes was assessed by blood testing and questionnaire. RESULTS: Mean age was 70. Multiple (≥4) brain infarcts and severe WMH occurred more frequently in African Caribbeans (18/43%), than Europeans (7/33%, P=0.05/0.008). Separately, clinic and night-time ambulatory BP were significantly associated with severe WMH in both ethnic groups; when both were entered into the model, the association for clinic SBP was attenuated and lost statistical significance [1.00 (0.98-1.02) P=0.9 in Europeans, 1.00 (0.97-1.04) P=0.9 in African Caribbeans], whereas the association for night-time SBP was retained [1.04 (1.02-1.07) P<0.001 in Europeans, 1.08 (1.03-1.12), P=0.001 in African Caribbeans]. The greater age-adjusted and sex-adjusted risk of severe WMH in African Caribbeans compared with Europeans [2.08 (1.15-3.76) P=0.02], was attenuated to 1.45 [(0.74-2.83) P=0.3] on adjustment for clinic and night-time systolic pressure, antihypertensive medication use and glycated haemoglobin. CONCLUSION: African Caribbeans have a greater burden of subclinical cerebrovascular disease than Europeans. This excess is related to elevated clinic and ambulatory BP, and to hyperglycaemia.