Study in Tanzania of impaired glucose tolerance. Methodological myth?

Short-term reproducibility of impaired fasting glycaemia, impaired glucose tolerance and diabetes The ADDITION study, DK

We evaluated variations in glucose measurements and the reproducibility of glucose tolerance classification in a high-risk screening setting in general practice. Screening for diabetes was performed in persons aged 40-69 years. Based on capillary fasting (FBG) and 2-h blood glucose (2 hBG) individuals with impaired fasting glycaemia (IFG), impaired glucose tolerance (IGT) and diabetes had a second test done after 14 days. Intra-individual coefficients of variation (CV) were estimated in each glucose tolerance class using the approximation CV(2)(x)=var(ln(x)). Bland-Altman plots with limits of agreement were made. In the total population, the CV(intra) was 7.9% and 13.8% for FBG and 2 hBG, respectively. Limits of agreement ranged from -1.15 to 1.67 mmol/l for FBG and from - 2.62 to 3.27 mmol/l for 2 hBG. One individual with IFG and 22.5% with IGT had diabetes at the second test, 76.1% with diabetes had this diagnosis confirmed, and about 30% with IFG and IGT had normal glucose tolerance at the second test. The expected values of repeated capillary blood glucose measurements were about+/-1 and+/-3 mmol/l for FBG and 2 hBG, respectively. Yet, 70% of high-risk prediabetic individuals were persistently classified with abnormal glucose regulation; diabetes was confirmed in 76% of the cases.

High incidence of type 2 diabetes and increasing conversion rates from impaired fasting glucose and impaired glucose tolerance to diabetes in Mauritius

OBJECTIVE

To describe the incidence of different stages of glucose intolerance in a population from Mauritius followed over 11 years. RESEARCH DESIGN, METHODS AND SUBJECTS: Population-based surveys were undertaken in the multi-ethnic nation of Mauritius in 1987, 1992 and 1998 with 5083, 6616 and 6291 participants, respectively. Questionnaires, anthropometric measurements, and a 2-h 75-g oral glucose tolerance test were included. Three cohorts aged between 25 and 79 years with classifiable glucose tolerance data were identified; 3680 between 1987 and 1992, 4178 between 1992 and 1998, and 2631 between 1987 and 1998. Glucose tolerance was classified according to WHO 1999 criteria.

RESULTS

The incidence rate of type 2 diabetes was higher between 1992 and 1998 than between 1987 and 1992. In men, the incidence was similar between cohorts (24.5 and 25.4 per 1000 person-years) whereas the incidence increased in women (23.3 and 16.4 per 1000 person-years). The incidence of diabetes peaked in the 45-54 year age group and then plateaued or fell. The incidences of impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) decreased in both men and women. Of normoglycaemic subjects at baseline, more women than men developed IGT and more men than women developed IFG. Of those labelled as IFG in 1987, 38% developed diabetes after 11 years. The corresponding figure for IGT was 46%.

CONCLUSIONS

In this study, we report changes in incidence rates of glucose intolerance over a 11-year period. In particular, differences between men and women were observed. The increased incidence of IGT in women compared with men, and increased incidence of IFG in men compared with women was consistent with, and explains the sex biases seen in the prevalences of these states.

Diabetes in the Caribbean: results of a population survey from Spanish Town, Jamaica

AIMS

To characterize the prevalence of diabetes and associated risk attributes in the Jamaican population.

METHODS

A random population sample was recruited by door-to-door canvassing (n = 1303). A final participation of 60% was achieved. Oral glucose tolerance testing was conducted after an overnight fast and standard anthropometric and demographic data were collected.

RESULTS

The prevalence of Type 2 diabetes mellitus was 9.8% (95% confidence interval (CI) 7.2-12.4) among men and 15.7% (95% CI 13.1-18.3) among women with an overall prevalence of 13.4% (95% CI 11.5-15.2). Impaired glucose tolerance was found among 12.3% of men and 14.7% of women. The sex patterns were consistent with a fourfold excess of obesity in women compared to men. The odds ratios for diabetes, fourth vs. first quartiles were 5.42 (95% CI 2.02-16.88) in men and 3.32 (95% CI 1.73-6.63) in women for body mass index (BMI) and 17.39 (95% CI 3.86-78.27) in men and 5.48 (95% CI 2.84-11.00) in women for WHR in a logistic model controlling for age. The population attributes risk percentage, for diabetes, of being overweight and having waist-to-hip ratio (WHR) greater than the median (0.80) were 66% and 80%, respectively. The contribution of central obesity, as characterized by WHR, was also significant in sex-specific multivariate models that included age and BMI. Prevalent hypertension and family history of diabetes were likewise associated with increased odds of having the disease.

CONCLUSIONS

The prevalence of diabetes in Jamaica now exceeds that observed among European-origin populations and reflects the emerging epidemic of obesity. The excess risk for this population could not be attributed entirely to relative weight. The pronounced sexual dimorphism in diabetes prevalence most likely reflects the substantial excess of obesity among women compared to men. Like many other island nations, Caribbean societies now appear to be at substantial risk of diabetes.

Is there a role for glycosuria testing in sub-Saharan Africa?

BACKGROUND

With increasing urbanization and westernization, rates of diabetes in sub-Saharan Africa (sSA) are likely to rise. Early detection and intervention plays an important role in delaying development of complications. In sSA in particular there is need for an affordable, reliable, safe, feasible test to avert human suffering and exhausting already stressed health facilities.

METHODS

Data from two large community-based studies were used to assess the value of glycosuria testing in the detection of diabetes in adults in a sub-Saharan country. A first study (A) tested participants for glycosuria by dipstick; if positive, fasting capillary glucose was measured. A later study (B) measured glucose concentration in venous blood 2 h after a 75-g glucose load; if glycaemia was > or = 10 mmol/l, urine was tested for glycosuria.

RESULTS

The positive predictive value of glycosuria for a diagnosis of diabetes (fasting glucose > or = 6.7 mmol/l) was 48%. Sensitivity was 64% (57% if a 2-h-value > or = 10 mmol/l was used as gold standard). Sensitivity was higher among overweight and/or hypertensive subjects, among elderly people in the urban area, and among subjects with higher blood glucose levels. Extrapolated specificity was 99.7%, and the likelihood ratio 190.

CONCLUSIONS

Glycosuria testing can identify a considerable number of undiagnosed diabetic patients when specially targeted at high-risk groups (obese, hypertensive, or elderly people). Dipstick glycosuria testing is an appropriate, safe, feasible test for sSA, where the prevalence of diabetes is expected to increase considerably in the near future.

Intra-individual variation of glucose, specific insulin and proinsulin concentrations measured by two oral glucose tolerance tests in a general Caucasian population: the Hoorn Study

We studied the intra-individual variation in plasma glucose, specific serum insulin and serum proinsulin concentrations, measured by two 75-g oral glucose tolerance tests in an age, sex, and glucose tolerance stratified random sample from a 50-74-year-old Caucasian population without a history of diabetes mellitus. The intra-individual variation was assessed by the standard deviation of the test-retest differences (SDdif). For subjects with normal (n = 246), impaired glucose tolerance (n = 198), and newly detected diabetes (n = 80) classified at the first test, the following (SDdif/median level of individual average scores) were found: fasting glucose: 0.4/5.4, 0.5/5.9 and 0.7/7.2 mmol/l; 2-h glucose: 1.3/5.6, 1.8/8.5 and 2.3/12.8 mmol/l; fasting insulin: 23/76, 32/89 and 30/116 pmol/l; 2-h insulin: 190/303, 278/553 and 304/626 pmol/l; fasting proinsulin: 4/8, 6/13 and 9/18 pmol/l; 2-h proinsulin: 19/49, 23/84 and 33/90 pmol/l, respectively. In both glucose, proinsulin and insulin concentrations the total intra-individual variation was predominantly determined by biological variation, whereas analytical variation made only a minor contribution. The SDdif can easily be interpreted, as 95% of the random test-retest differences will be less than 2.SDdif, or in terms of percentage, less than (2.SDdif/median level of individual average score) 100. Therefore, for subjects with normal glucose tolerance, 95% of the random test-retest differences will be less than 15% (fasting glucose), 46% (2-h glucose), 61% (fasting insulin), 125% (2-h insulin), 100% (fasting proinsulin) and 78% (2-h proinsulin) of the median value of the individual average scores. No substantial independent association of either age, gender or obesity with the intra-individual variation in glucose, proinsulin, or insulin concentrations was found.

Prevalence of diabetes mellitus in an elderly Finnish population

The prevalence of diabetes mellitus was investigated in a northern Finnish community population aged 70 years or over. Of the eligible 483 persons, 78.5% (n = 379) took part in the study. The presence of diabetes mellitus was assessed by questions about the participants' previously diagnosed diabetes and 2 h oral glucose tolerance tests, which were performed according to the current WHO criteria. Only the participants who were on oral hypoglycaemic drugs or insulin treatment were excluded from the 2 h oral glucose tolerance tests. In the total population the prevalence of Type 2 diabetes was 22.0% among men and 28.2% among women; the difference between sexes was not significant (women's risk ratio (RR) 1.3, 95% confidence interval (CI) 0.9-1.9). Among those aged 80 years or over the risk ratio for women was 11.3 compared with men (95% CI 1.6-79.5). Among men the prevalence was higher in the age group 70-79 years compared with those aged 80 years or over (RR 8.1, 95% CI 1.2-57.1). By contrast, among women, diabetes was less common among those aged 70-79 years compared with those aged 80 years or over (RR 0.6, 95% CI 0.4-1.0). The proportion of undiagnosed diabetes was clearly over one-third among men and just over one-third among women. Of men, 31.9% suffered from impaired glucose tolerance; the corresponding figure for women was 35.3%. The comparatively high proportion of undiagnosed diabetes and impaired glucose tolerance among elderly people lends support to the more frequent use of the 2 h glucose tolerance test in clinical practice.

Problems related to definitions and epidemiology of type 2 (non-insulin-dependent) diabetes mellitus: studies throughout the world

Many studies of Type 2 (non-insulin-dependent) diabetes mellitus assume that the condition is homogeneous and clearly defined. There are, however, several problems with these assumptions. Thus, definition of Type 2 diabetes is one of exclusion of other types (insulin-dependent, malnutrition-related, gestational and other rarer types) and inevitably contains a heterogeneous group of disorders the aetiology of which is largely unclear, and separation from the insulin-dependent type can be problematic. Diagnosis is also imprecise in asymptomatic subjects due to the lack of accurate diagnostic tools and lack of clear distinction of impaired glucose tolerance. An alternative to the oral glucose tolerance test is urgently needed. Epidemiological studies of Type 2 diabetes and its complications are also fraught with difficulties due to variability of the oral glucose tolerance test, potential problems in glucose measurement, heterogeneity, population selection and problems in international comparisons due to differing age structures and life expectancy. Great care is needed in all studies of Type 2 diabetes to ensure that the groups under study are properly selected, well-defined and fully described.

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.

The genetics of non-insulin-dependent diabetes mellitus in south India: an overview

Non-insulin-dependent diabetes mellitus affects approximately 10% of urban Indian and Indian migrant populations and as such carries major health implications for these groups. Whilst a strong genetic component to the aetiology of non-insulin-dependent diabetes mellitus is incontestable, progress in identifying the specific genetic determinants involved in its pathogenesis has been slow. In studies of South Indian pedigrees, preliminary segregation analysis indicates that non-insulin-dependent diabetes mellitus is likely to be a polygenic disease. A number of candidate genes have been studied with the aim of demonstrating either association or linkage with the disease; in South Indians the only positive results thus far have been associations between non-insulin-dependent diabetes mellitus and the genes for insulin, apolipoprotein D and complement component C4B. However, it seems likely that these genes contribute only a small proportion of the genetic susceptibility to non-insulin-dependent diabetes mellitus in this ethnic group and that the major genes underlying glucose intolerance remain to be determined.

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.

Distinguishing between persistent and transient impaired glucose tolerance using a prediction model

Screening for impaired glucose tolerance (IGT) and Type 2 (non-insulin dependent) diabetes was carried out in 777 people and those with high blood glucose levels completed three 2-h oral glucose tolerance tests (OGTT). Blood lipid levels, fasting and 2-h insulin levels, body mass index, and blood pressure were also measured and family history of Type 2 diabetes recorded. Fifty people were identified with IGT and of these 21 were found to have persistent IGT and 29 transient IGT. A model including the variables body mass index, fasting and 2-h insulin levels, fasting triglycerides and family history of Type 2 diabetes was developed using the Speigelhalter-Knill-Jones weighting method to predict subjects with persistent IGT. This model could be useful in identifying people with persistent IGT and therefore eliminate the need for repeat OGTTs which are time consuming and expensive.

Diabetes mellitus, impaired glucose tolerance and mortality among elderly men: the Finnish cohorts of the Seven Countries Study

We studied the association of glucose intolerance with total and cause-specific mortality during a 5-year follow-up of 637 elderly Finnish men aged 65 to 84 years. Total mortality was 276 per 1000 for men aged 65 to 74 years and 537 per 1000 for men aged 75 to 84 years. Five-year total mortality adjusted for age was 364 per 1000 in diabetic men, 234 per 1000 in men with impaired glucose tolerance and 209 per 1000 in men with normal glucose tolerance. The relative risk of death among diabetic men was 2.10 (95% confidence interval 1.26 to 3.49) and among men with impaired glucose tolerance 1.17 (95% confidence interval 0.71 to 1.94) times higher compared with men with normal glucose tolerance. Cardiovascular disease was the most common cause of death in every glucose tolerance group. The multivariate adjusted relative risk of cardiovascular death was increased (1.55) in diabetic patients, albeit non-significantly (95% confidence interval 0.84 to 2.85). Diabetes resulted in an increased risk of cardiovascular mortality among men aged 65-74 years but not among the 75- 84-year-old men. Relative risk of death from non-cardiovascular causes was slightly increased among diabetic subjects. In conclusion, diabetes mellitus is a significant determinant of mortality among elderly Finnish men.