Study in Tanzania of impaired glucose tolerance. Methodological myth?

During a study of diabetes prevalence in six rural Tanzanian communities, a repeat oral glucose tolerance test (OGTT) was carried out in 514 subjects greater than or equal to 15 yr of age within 1 wk of an initial 75-g OGTT. In 498 subjects, blood glucose was measured 2 h after the glucose load on both occasions, and in 175 subjects, fasting blood glucose measurement was also repeated. Of the 498 subjects, 245 had normal glucose tolerance in the first test and were selected at random for further testing; 223 subjects had impaired glucose tolerance (IGT), and 30 had diabetic values. Diabetes and IGT were diagnosed on the basis of the 2-h blood glucose values. In the second test, 241 (98.4%) of the 245 subjects with normal tolerance continued in this category and 4 (1.6%) showed IGT. Of the 223 with IGT in the first test, 171 (76.2%) reverted to normal on the second test, 7 (3.1%) had diabetic values, and 45 (20.2%) persisted with IGT. Of the 30 subjects diagnosed as diabetic in the first test, 8 (26.7%) remained with diabetic values, 11 (36.7%) had IGT, and 11 (36.7%) were normal. Based on the second test, the population-prevalence rates of diabetes and IGT would have been 0.5 and 3.3% vs. 1 and 7.6% based on the first test. There was a significant downward trend in the mean 2-h blood glucose values in all three diagnostic groups. Regression toward the mean could not account for the downward shift in blood glucose values observed on retesting.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes is not caused by cassava toxicity. A study in a Tanzanian community.

OBJECTIVE: To test the hypothesis that consumption of cassava with liberation of cyanide causes diabetes in malnourished individuals. RESEARCH DESIGN AND METHODS: Glucose tolerance was assessed in two rural communities in Tanzania; in one (Nyambori), the main source of calories was cassava; and in the other (Uswaa), cassava was rarely eaten. Undernutrition was prevalent in both communities. The people of Nyambori were known to have high dietary cyanide exposure for many years from consumption of insufficiently processed cassava. Of the 1435 people in Nyambori greater than or equal to 15 yr old, 1067 (74%) were surveyed, and 1429 of 1472 (97%) eligible subjects in Uswaa were surveyed. All had 75-g oral glucose tolerance tests and measurement of BMI. Plasma and urine thiocyanate and blood cyanide also were measured in some subjects. RESULTS: Mean +/- SD plasma and urine thiocyanate levels in Nyambori were 296 +/- 190 and 497 +/- 457 microM (n = 204), respectively, compared with 30 +/- 37 and 9 +/- 13 microM, respectively, in Uswaa (n = 92) (P less than 0.001 for all differences). The mean blood cyanide level in Nyambori was elevated (1.4 [range 0.1-30.2] microM; n = 91). The prevalence of diabetes in the cassava village (Nyambori) was 0.5% compared with 0.9% in Uswaa (NS). The prevalence of IGT was similar in the two villages in the 15- to 34- and the 34- to 54-yr-old age-groups; but in those greater than or equal to 55 yr old, IGT was higher in Nyambori (17.4 vs 7.2%, P = 0.029). Mean fasting and 2-h blood glucose levels were slightly higher in Nyambori village after adjusting for age, sex, and BMI (4.5 vs. 4.2 and 5.0 vs. 4.4 mM, respectively). CONCLUSIONS: High dietary cyanide exposure was not found to have had a significant effect on the prevalence of diabetes in an undernourished population in Tanzania. Cassava consumption is thus highly unlikely to be a major etiological factor in so-called MRDM, at least in East Africa.

Low prevalence of risk factors for coronary heart disease in rural Tanzania.

A community-based survey was used to assess the prevalence of risk factors for coronary heart disease (CHD) in rural Tanzanians. In all, 8581 subjects (3705 men, 4876 women) aged > or = 15 years in eight villages in three regions in rural Tanzania representing a range of socioeconomic deprivation were studied. The main outcome measures were serum cholesterol and triglyceride level, blood pressure and prevalence of dyslipidaemia, hypertension, smoking, overweight, impaired glucose tolerance (IGT) and diabetes; as well as ECG changes. Mean serum cholesterol levels in men were 4.2, 3.4 and 3.7 mmol/l, and in women 4.4 3.6 and 3.9 mmol/l in Kilimanjaro, Morogoro and Mara regions respectively. In Kilimanjaro region 17.4% of men and 19.0% of women had values above 5.2 mmol/l compared with only 5.0% and 6.7% in Morogoro region and 4.8% and 6.9% respectively in Mara region. Systolic and diastolic blood pressures increased with age in both men and women in all three regions with the most marked increase in Kilimanjaro region and the smallest rise in Mara region. Mean age-adjusted values were highest in Kilimanjaro region (124/75 mm Hg, and 125/76 mm Hg in men and women respectively) and lowest in Mara region (120/70 mm Hg in men and 118/68 mm Hg in women). Hypertension was found in 6.6% of men and 7.5% of women in Kilimanjaro region, 3.3% and 4.7% in Morogoro, and 2.6% and 3.4% in Mara region. Cigarette smoking was found in 42.6% of men in Kilimanjaro region, 28.2% of Morogoro region and 8.6% in Mara region. Less than 4% of women smoked in all three regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary heart disease risk factors in sub-Saharan Africa: studies in Tanzanian adolescents.

STUDY OBJECTIVE: To assess the level of cardiovascular risk factors in young people in sub-Saharan Africa living in rural and urban settings. DESIGN: Cross sectional survey of the population aged 15 to 19 years. SETTING: Eight rural Tanzanian villages in three regions, and two districts in Dar es Salaam. PARTICIPANTS: 664 males and 803 females in rural villages and 85 males and 121 females in the city. Response rates for total population were 74% to 94% in the rural areas and 60% in the city. MEASUREMENTS AND RESULTS: Measurements included blood pressure, body mass index, serum lipids, and blood glucose concentrations (fasting and two hours after 75 g glucose). Blood pressure was slightly but significantly higher in young women than in young men (115/67 mmHg versus 113/65 mmHg) and increased significantly with age. Only 0.4% subjects had blood pressure greater than 140 and/or 90 mmHg. There were no urban-rural differences. Body mass index was higher in females (mean (SD) 20.3 (2.8) kg/m2) than males (18.5 (2.1)). Overweight was found in only 0.6% at age 15 years but 5.4% at age 19 years. Serum cholesterol concentrations were low at 3.5 mmol/l in males and 3.7 mmol/l in females. Only 7% had values above 5.2 mmol/l. The highest concentrations were found in the city and in Kilimanjaro, the most prosperous rural region. Serum triglycerides were 1.0 (0.5) mmol/l in males and 1.1 (0.5) mmol/l in females, and were highest in the city dwellers. Diabetes was rare (0.28% males, 0.12% females) but impaired glucose tolerance was present in 4.7% and 4.1% respectively. Drinking alcohol was equally prevalent in males and females, reaching 30% at age 19 years. Only 0.4% of females smoked compared with 7.3% of males. Smoking was commoner in rural areas that in the city. CONCLUSIONS: Several risk factors for cardiovascular disease were found in Tanzanian adolescents, but levels were much lower than in studies reported from developed nations. The challenge is to maintain these low levels as the population becomes more urbanised and more affluent.

Schistosomiasis prevalence after administration of praziquantel to school children in Melela village, Morogoro region, Tanzania.

A study of the prevalence of schistosomiasis was carried out in 253 school children in Melela, Tanzania, one year after a single dose of praziquantel, 40 mg/kg body weight. The cure rate was 90.4%. However the new incidence estimate was 21.2% in children who were initially negative. The use of reagent strips in urine tests for the detection of urinary schistosomiasis was also evaluated. The presence of blood in the urine was highly sensitive (> 96%) and specific (87%). The sensitivity of proteinuria was less, but it was highly specific (94%). This study shows that chemotherapy will have to be combined with other measures to achieve lasting benefits and raises the question as to how often the population should be treated. It also confirms the value of urine test strips as an indirect diagnostic test for urinary schistosomiasis in an endemic area. Further follow-up is necessary to make useful predictions concerning incidence and reinfection rates in the community. This will also help in deciding how often chemotherapy should be given to the population.

Is diabetes mellitus related to undernutrition in rural Tanzania?

OBJECTIVE: To investigate the relation between undernutrition and diabetes. DESIGN: Survey of glucose tolerance in rural Tanzania. SETTING: Eight villages in three widely separated regions of Tanzania. SUBJECTS: 8581 people aged 15 and above: 3705 men and 4876 women. MAIN OUTCOME MEASURES: Oral glucose tolerance, body mass index, height, and low haemoglobin and cholesterol concentrations. RESULTS: In the eight villages 42.7-56.9% of all men and 30.0-45.2% of all women had a body mass index below 20 kg/m2; the lowest quintile was 18.2 kg/m2 in men and 18.6 kg/m2 in women. The prevalence of diabetes did not change significantly from the lowest to the highest fifths of body mass index in men (lowest 1.6% (95% confidence interval 0.8% to 2.9%) v highest 1.3% (0.7% to 2.5%)) or women (1.1% (0.6% to 2.1%) v 0.5% (0.2% to 1.2%)). In men and in women prevalence of impaired glucose tolerance was greater in the lowest fifths of height (8.2% (6.3% to 10.6%), and 11.1% (9.2% to 13.3%)) respectively and body mass index (9.6% (7.5% to 12.1%), and 8.4% (6.7% to 10.5%)) than in the highest fifths (impaired glucose tolerance 4.7% (3.4% to 6.5%); and 5.1% (3.9% to 6.7%); body mass index 5.1% (3.7% to 7.0%), and 7.7% (6.2% to 9.6%). CONCLUSION: Rates of diabetes were not significantly associated with low body mass index or height, but overall rates were much lower than those in well nourished Western populations. Increased impaired glucose tolerance in the most malnourished people may reflect the larger glucose load per kilogram weight. The role of undernutrition in the aetiology of diabetes must be questioned.

Outlook for survivors of childhood in sub-Saharan Africa: adult mortality in Tanzania. Adult Morbidity and Mortality Project.

OBJECTIVE: To measure age and sex specific mortality in adults (15-59 years) in one urban and two rural areas of Tanzania. DESIGN: Reporting of all deaths occurring between 1 June 1992 and 31 May 1995. SETTING: Eight branches in Dar es Salaam (Tanzania's largest city), 59 villages in Morogoro rural district (a poor rural area), and 47 villages in Hai district (a more prosperous rural area). SUBJECTS: 40,304 adults in Dar es Salaam, 69,964 in Hai, 50,465 in Morogoro rural. MAIN OUTCOME MEASURES: Mortality and probability of death between 15 and 59 years of age (45Q15). RESULTS: During the three year observation period a total of 4929 deaths were recorded in adults aged 15-59 years in all areas. Crude mortalities ranged from 6.1/1000/year for women in Hai to 15.9/1000/year for men in Morogoro rural. Age specific mortalities were up to 43 times higher than rates in England and Wales. Rates were higher in men at all ages in the two rural areas except in the age group 25 to 29 years in Hai and 20 to 34 years in Morogoro rural. In Dar es Salaam rates in men were higher only in the 40 to 59 year age group. The probability of death before age 60 of a 15 year old man (45Q15) was 47% in Dar es Salaam, 37% in Hai, and 58% in Morogoro; for women these figures were 45%, 26%, and 48%, respectively. (The average 45Q15s for men and women in established market economies are 15% and 7%, respectively.) CONCLUSION: Survivors of childhood in Tanzania continue to show high rates of mortality throughout adult life. As the health of adults is essential for the wellbeing of young and old there is an urgent need to develop policies that deal with the causes of adult mortality.

Diabetes mellitus as a cause of death in sub-Saharan Africa: results of a community-based study in Tanzania. The Adult Morbidity and Mortality Project.

The aim of this study was to determine the contribution of diabetes mellitus to all-cause mortality and diabetes mortality rates in adults 15 years and above living in one urban and two rural areas of Tanzania (Dar es Salaam, Hai and Morogoro Rural Districts). The three surveillance populations comprised 307,912 persons. Prospective monitoring of all deaths between 1 June 1992 and 31 May 1995 was carried out. Cause of death was determined by verbal 'autopsy' conducted with relatives of the deceased. In total, 4299 deaths were recorded in children (aged < 15 years) and 8054 in adults. In children there were no reported deaths associated with diabetes (due to or in children with diabetes). The adult male mortality rates associated with diabetes were 34, 30, and 15 per 100,000 per year in Dar es Salaam, Hai and Morogoro Rural Districts respectively. The figures in women were 21, 18, and 4 per 100,000 per year, respectively. The percentages of all adult male deaths associated with diabetes were 2.6%, 2.1% and 0.7% respectively. In women the percentages were 1.7%, 1.8%, and 0.2% respectively. Acute metabolic complications, infection, and stroke each accounted for approximately 30% of all diabetic deaths. Thus diabetes mortality rates varied between the three surveillance areas, being lowest in the poorest rural area. Rates were higher in men in all areas. While care is required in the comparison of mortality rates between countries, it was noteworthy that Tanzania, a country with a low diabetes prevalence, had diabetes mortality rates which were higher than or comparable to rates in Mauritius and the United States. Most patients died from preventable causes, indicating a need for improved case-management of diabetic emergencies as well as better detection and treatment of hypertension.

No deterioration of oral glucose tolerance during pregnancy in rural Tanzania.

There is still controversy concerning the reference ranges for glucose tolerance tests in pregnancy. The WHO has recommended the universal use of the 75 g oral glucose load with 2-h post-load values of greater than 6.7 mmol l-1 to be considered impaired glucose tolerance (IGT) in the non-pregnant, and equivalent to gestational diabetes in the pregnant. Some data are available for pregnant Caucasians but little information is available for other ethnic groups. Oral glucose tolerance tests (75 g) have therefore been performed in 189 pregnant women in rural Tanzania. Mean fasting blood glucose values were 4.0 mmol l-1 in non-pregnant women, and 3.7, 3.5, and 3.3 mmol l-1 in pregnant women in the first, second, and third trimesters, respectively. Two-hour OGTT values were 4.7 mmol l-1, and 4.6, 4.5, and 4.2 mmol l-1 while the upper limit of normal values (mean + 2SD) were 7.1 mmol l-1, and 6.8, 6.8, and 6.1 mmol l-1. The 2-h glucose levels are therefore close to WHO recommendations but lower than those reported for Caucasians. By contrast with reports for Caucasians, glucose tolerance did not deteriorate during pregnancy. The prevalence of diabetes and IGT was zero in the pregnant group.

Stroke mortality in urban and rural Tanzania. Adult Morbidity and Mortality Project.

BACKGROUND: Most data for stroke mortality in sub-Saharan Africa are hospital based. We aimed to establish the contribution of cerebrovascular disease to all-cause mortality and cerebrovascular disease mortality rates in adults aged 15 years or more in one urban and two rural areas of Tanzania. METHODS: Regular censuses of the three surveillance populations consisting of 307,820 people (125,932 aged below 15 years and 181,888 aged 15 or more) were undertaken with prospective monitoring of all deaths arising in these populations between June 1, 1992 and May 31, 1995. Verbal autopsies were completed with relatives or carers of the deceased to assess, when possible, the cause of death. FINDINGS: During the 3-year observation period 11,975 deaths were recorded in the three surveillance areas, of which 7629 (64%) were in adults aged 15 years or more (4088 [54%] of these in men and 3541 [46%] in women). In the adults, 421 (5.5%) of the deaths were attributed to cerebrovascular disease, 225 (53%) of these in men and 196 (47%) in women. The yearly age-adjusted rates per 100,000 in the 15-64 year age group for the three project areas (urban, fairly prosperous rural, and poor rural, respectively) were 65 (95% CI 39-90), 44 (31-56), and 35 (22-48) for men, and 88 (48-128), 33 (22-43), and 27 (16-38) for women, as compared with the England and Wales (1993) rates of 10.8 (10.0-11.6) for men and 8.6 (7.9-9.3) for women. INTERPRETATION: We postulate that the high rates in Tanzania were due to untreated hypertension. Our study assessed mortality over a single time period and therefore it is not possible to comment on trends with time. However, ageing of the population is likely to lead to a very large increase in mortality from stroke in the future.

Application of the new ADA criteria for the diagnosis of diabetes to population studies in sub-Saharan Africa. American diabetes association.

AIMS: To examine the implications for epidemiological studies of the American Diabetes Association (ADA) recommendation that the fasting blood glucose at a lowered level becomes the main diagnostic test for diabetes on cross-sectional-based data from sub-Saharan Africa. METHODS: Data from 11 surveys conducted in rural, peri-urban and urban Cameroon (n = 1804), South Africa (n = 3799) and Tanzania (n = 10013) which measured fasting (ADA criteria) and 2-h blood glucose concentrations during a standard 75 g OGTT (old WHO criteria) were analysed. RESULTS: The prevalence of diabetes was higher in eight of the 11 surveys when applying the new ADA compared to the old WHO criteria. With the exception of one population (Mara, Tanzania) the absolute difference in prevalence between the two classifications tended to be small (< 2%). There was considerable variation in the categorization of individuals using the ADA and old WHO criteria. The level of agreement between the two ranged from fair to good (Kappa statistic 0.17-0.86). The prevalence of impaired fasting glycaemia (IFG) was lower than that of impaired glucose tolerance (IGT) in 10 of the surveys and the agreement between the two was fair, < or = 0.26 in all the surveys. CONCLUSIONS: Although the use of the new ADA fasting criteria for prevalence surveys is an attractive and practical option, particularly in Africa, further information is required on the characteristics and prognosis of individuals classified as IFG or diabetic by the fasting criteria, prior to wide adoption of the ADA criteria. Ideally measurement of both fasting and two low glucose concentrations should remain the standard for epidemiological studies.

Age specific prevalence of impairment and disability relating to hemiplegic stroke in the Hai District of northern Tanzania. Adult Morbidity and Mortality Project.

OBJECTIVES: To determine the age specific prevalence of impairment and disability relating to hemiplegic stroke in one rural area of Tanzania. METHODS: During the yearly house to house census of the study population of 148 135 (85 152 aged 15 and over) in August 1994, specific questions were asked to identify those who might be disabled from stroke. People thus identified were subsequently interviewed and examined by one investigator. In those in whom the clinical diagnosis of stroke was confirmed a more detailed interview and examination relating to risk factors and recovery was carried out. RESULTS: One hundred and eight patients, 61 men and 47 women, were identified with a median age of 70 (range 18-100). Median age at first stroke was 65 years. The age specific rates in this study were lower than previous studies in developed countries. All were cared for at home although 23 (21%) were bedbound. CONCLUSIONS: Although prevalence of impairment and disability related to stroke in this population as a whole was low this is mainly explained by the age structure, with less than 6% being aged 65 and over. Age standardised rates for stroke with residual disability were about half those found in previous studies in developed countries. Death from stroke in Africa may be higher but data are limited. With the demographic transition stroke is likely to become a more important cause of disability in sub-Saharan Africa.

Prevalence of diabetes and impaired glucose tolerance in rural Tanzania.

The prevalence of diabetes mellitus and impaired glucose tolerance (IGT) was assessed by use of WHO diagnostic criteria in 6299 Africans aged 15 years and above living in six villages in Tanzania. 0.87% (1.1% male, 0.68% female) had diabetes and 7.8% (6.9% male, 7.7% female) had IGT. Prevalence rates were 1.1% and 8.4%, respectively, when age-adjusted to the USA population. Only 7 (13.5%) of the 53 individuals with diabetes had been known to have the disorder; 34 (74%) of the other 46 were symptom-free. Mean age was 54 (SD 20) for diabetic subjects and 37 (17) years for the whole population. Diabetes and IGT rates did not differ significantly between villages despite geographical, socioeconomic, and dietary differences. Diabetes rates increased modestly with age and body mass index (BMI). Fasting blood glucose (FBG) levels did not rise significantly with age but correlated positively with systolic blood pressure (BP) and negatively with haemoglobin concentration (Hb) and BMI. The 2 hour post-glucose load blood glucose values correlated positively with age, sex, and systolic BP and negatively with Hb. Diabetes is less prevalent in rural Africa than in developed countries, even when age has been corrected for. This difference is probably related to body weight, diet, and exercise.