Dirk L. Christensen

Moving to an A1C-Based Diagnosis of Diabetes Has a Different Impact on Prevalence in Different Ethnic Groups

OBJECTIVE To compare screen-detected diabetes prevalence and the degree of diagnostic agreement by ethnicity with the current oral glucose tolerance test (OGTT)-based and newly proposed A1C-based diagnostic criteria. RESEARCH DESIGN AND METHODS Six studies (1999–2009) from Denmark, the U.K., Australia, Greenland, Kenya, and India were tested for the probability of an A1C ≥6.5% among diabetic case subjects based on an OGTT. The difference in probability between centers was analyzed by logistic regression adjusting for relevant confounders. RESULTS Diabetes prevalence was lower with the A1C-based diagnostic criteria in four of six studies. The probability of an A1C ≥6.5% among OGTT-diagnosed case subjects ranged widely (17.0–78.0%) by study center. Differences in diagnostic agreement between ethnic subgroups in the U.K. study were of the same magnitude as between-country comparisons. CONCLUSIONS A shift to an A1C-based diagnosis for diabetes will have substantially different consequences for diabetes prevalence across ethnic groups and populations.

Obesity and regional fat distribution in Kenyan populations: Impact of ethnicity and urbanization

Background: Obesity is increasing rapidly in Africa, and may not be associated with the same changes in body composition among different ethnic groups in Africa. Objective: To assess abdominal visceral and subcutaneous fat thickness, prevalence of obesity, and differences in body composition in rural and urban Kenya. Subjects and methods: In a cross-sectional study carried out among Luo, Kamba and Maasai in rural and urban Kenya, abdominal visceral and subcutaneous fat thicknesses were measured by ultrasonography. Height and weight, waist, mid-upper arm circumferences, and triceps skinfold thickness were measured. Body mass index (BMI), arm fat area (AFA) and arm muscle area (AMA) were calculated. Results: Among 1430 individuals (58.3% females) aged 17–68 years, abdominal visceral and subcutaneous fat, BMI, AFA and waist circumference (WC) increased with age, and were highest in the Maasai and in the urban population. AMA was only higher with increasing age among males. The prevalence of overweight (BMI ≥ 25) (39.8% vs. 15.8%) and obesity (BMI ≥ 30) (15.5% vs. 5.1%) was highest in the urban vs. rural population. Conclusion: Abdominal visceral and subcutaneous fat thickness was higher with urban residency. A high prevalence of overweight and obesity was found. The Maasai had the highest overall fat accumulation.

Prevalence of glucose intolerance and associated risk factors in rural and urban populations of different ethnic groups in Kenya.

OBJECTIVE To assess the prevalence of glucose intolerance in rural and urban Kenyan populations and in different ethnic groups. Further, to identify associations between lifestyle risk factors and glucose intolerance. RESEARCH DESIGN AND METHODS A cross-sectional study included an opportunity sample of Luo, Kamba, Maasai, and an ethnically mixed group from rural and urban Kenya. Diabetes and IGT were diagnosed using a standard OGTT. BMI, WC, AFA, AMA and abdominal subcutaneous and visceral fat thicknesses, physical activity and fitness were measured. Questionnaires were used to determine previous diabetes diagnosis, family history of diabetes, smoking habits, and alcohol consumption. RESULTS Among 1459 participants, mean age 38.6 years (range 17-68 years), the overall age-standardized prevalence of diabetes and IGT was 4.2% and 12.0%. The Luo had the highest prevalence of glucose intolerance among the rural ethnic groups. High BMI, WC, AFA, abdominal visceral and subcutaneous fat thickness, low fitness and physical activity, frequent alcohol consumption, and urban residence were associated with glucose intolerance. CONCLUSIONS The prevalence of diabetes and IGT among different Kenyan population groups was moderate, and highest in the Luo. The role of lifestyle changes and ethnicity on the effect of diabetes in African populations needs further exploration.

Diabetes Is a Risk Factor for Pulmonary Tuberculosis: A Case-Control Study from Mwanza, Tanzania

Background Diabetes and TB are associated, and diabetes is increasingly common in low-income countries where tuberculosis (TB) is highly endemic. However, the role of diabetes for TB has not been assessed in populations where HIV is prevalent. Methods A case-control study was conducted in an urban population in Tanzania among culture-confirmed pulmonary TB patients and non-TB neighbourhood controls. Participants were tested for diabetes according to WHO guidelines and serum concentrations of acute phase reactants were measured. The association between diabetes and TB, and the role of HIV as an effect modifier, were examined using logistic regression. Since blood glucose levels increase during the acute phase response, we adjusted for elevated serum acute phase reactants. Results Among 803 cases and 350 controls the mean (SD) age was 34.8 (11.9) and 33.8 (12.0) years, and the prevalence of diabetes was 16.7% (95% CI: 14.2; 19.4) and 9.4% (6.6; 13.0), respectively. Diabetes was associated with TB (OR 2.2, 95% CI: 1.5; 3.4, p<0.001). However, the association depended on HIV status (interaction, p = 0.01) due to a stronger association among HIV uninfected (OR 4.2, 95% CI: 1.5; 11.6, p = 0.01) compared to HIV infected (OR 0.1, 95% CI: 0.01; 1.8, p = 0.13) after adjusting for age, sex, demographic factors and elevated serum acute phase reactants. Conclusion Diabetes is a risk factor for TB in HIV uninfected, whereas the association in HIV infected patients needs further study. The increasing diabetes prevalence may be a threat to TB control.

Body dimensions, exercise capacity and physical activity level of adolescent Nandi boys in western Kenya

The aim of this study was to characterize untrained Nandi boys (mean age 16.6 years) from a town (n = 11) and from a rural area (n = 19) in western Kenya (altitude ˜2000 m.a.s.l.) in regard to their body dimensions, oxygen uptake and physical activity level. The town boys had a mean maximal oxygen uptake (VO2max) of 50 (range: 45–60) mL kg−1 min−1, whereas the village boys reached a value of 55 (37−63) mL kg−1 min−1 ( p<0.01) in VO2max. The running economy, determined as the oxygen cost at a given running speed, was 221 mL kg−1 km−1 (597 mL kg−0.75 km−1) for town as well as for village boys. The body mass index (BMI) was very low for town as well as for village boys (18.6 vs 18.4 kg m−2). The daily mean time spent working in the field during secondary school and doing sports were significantly higher in village boys compared to town boys (working in the field: 44.2 (0–128) vs 1.3 (0–11) min, p<0.01; sports: 32.0 (11–72) vs 12.8 (0–35) min, p<0.01, respectively). A positive correlation between the daily time spent doing sports and VO2max was found when pooling the data from the town and the village boys (R = 0.55, p<0.01). It is concluded that the body dimensions of adolescent Nandi town and village boys corresponds well with findings in Kenyan elite runners. They are very slender with relatively long legs. In addition, the VO2max of the village boys was higher than that of the town boys, which is probably due to a higher physical activity level of the village boys during secondary school.

Skiing across the Greenland icecap: divergent effects on limb muscle adaptations and substrate oxidation

SUMMARY This study investigates the adaptive response of the lower limb muscles and substrate oxidation during submaximal arm or leg exercise after a crossing of the Greenland icecap on cross-country skies. Before and after the 42-day expedition, four male subjects performed cycle ergometer and arm-cranking exercise on two separate days. On each occasion, the subjects exercised at two submaximal loads (arm exercise, 45 W and 100 W; leg exercise, 100 W and 200 W). In addition, peak oxygen uptake (V̇O2max) was determined for both leg and arm exercise. Before and after the crossing, a muscle biopsy was obtained from the vastus lateralis and the triceps brachii muscles prior to exercise (N=3). After the crossing, body mass decreased by 5.7±0.5 kg (in four of four subjects), whereas V̇O2max was unchanged in the arm (3.1±0.2 l min-1) and leg (4.0±0.1 l min-1). Before the crossing, respiratory exchange ratio (RER) values were 0.84±0.02 and 0.96±0.02 during submaximal arm exercise and 0.82±0.02 and 0.91±0.01 during submaximal leg exercise at the low and high workloads, respectively. After the crossing, RER was lower (in three of four subjects) during arm exercise (0.74±0.02 and 0.81±0.01) but was higher (in three of four subjects) during leg exercise (0.92±0.02 and 0.96±0.01) at the low and high workloads, respectively. Citrate synthase andβ -hydroxy-acyl-CoA-dehydrogenase activity was decreased by approximately 29% in vastus lateralis muscle and was unchanged in triceps brachii muscle. Fat oxidation during submaximal arm exercise was enhanced without a concomitant increase in the oxidative capacity of the triceps brachii muscle after the crossing. This contrasted with decreased fat oxidation during leg exercise, which occurred parallel to a decreased oxidative capacity in vastus lateralis muscle. Although the number of subjects is limited, these results imply that the adaptation pattern after long-term, prolonged, low-intensity, whole body exercise may vary dramatically among muscles.

Sleep duration and sleep quality are associated differently with alterations of glucose homeostasis.

Diabet. Med. 29, e354–e360 (2012)

Diabetes is a strong predictor of mortality during tuberculosis treatment: a prospective cohort study among tuberculosis patients from Mwanza, Tanzania

Strong evidence suggests diabetes may be associated with tuberculosis (TB) and could influence TB treatment outcomes. We assessed the role of diabetes on sputum culture conversion and mortality among patients undergoing TB treatment.

Cardiorespiratory fitness and physical activity in Luo, Kamba, and Maasai of rural Kenya

Although habitual physical activity energy expenditure (PAEE) and cardio‐respiratory fitness (CRF) are now well‐established determinants of metabolic disease, there is scarcity of such data from Africa. The aim of this study was to describe objectively measured PAEE and CRF in different ethnic populations of rural Kenya.

The role of diabetes on the clinical manifestations of pulmonary tuberculosis.

Objective  Diabetes is associated with pulmonary tuberculosis (TB), possibly due to impaired immunity, and diabetes may exacerbate the clinical manifestations of TB. Our aim was to assess the role of diabetes in the clinical manifestations of TB.