The metabolic syndrome as a predictor of incident diabetes mellitus in Mauritius

Aims : To assess the utility of the metabolic syndrome (MetS) and a Diabetes Predicting Model as predictors of incident diabetes.

Methods : A longitudinal survey was conducted in Mauritius in 1987 (n = 4972; response 80%) and 1992 (n = 3685; follow-up 74.2%). Diabetes status was retrospectively determined using 1999 World Health Organization (WHO) criteria. MetS was determined according to four definitions and sensitivity, positive predictive value (PPV), specificity and the association with incident diabetes before and after adjustment for MetS components calculated.

Results : Of the 3198 at risk, 297 (9.2%) developed diabetes between 1987 and 1992. The WHO MetS definition had the highest prevalence (20.3%), sensitivity (42.1%) and PPV (26.8%) for prediction of incident diabetes, the strongest association with incident diabetes after adjustment for age and sex [odds ratio 4.6 (3.5–6.0)] and was the only definition to show a significant association after adjustment for its component parts (in men only). The low prevalence and sensitivity of the International Diabetes Federation (IDF) and ATPIII MetS definitions resulted from waist circumference cut-points that were high for this population, particularly in men, and both were not superior to a diabetes predicting model on receiver operating characteristic analysis.

Conclusions : Of the MetS definitions tested, the WHO definition best identifies those who go on to develop diabetes, but is not often used in clinical practice. If cut-points or measures of obesity appropriate for this population were used, the IDF and ATPIII MetS definitions could be recommended as useful tools for prediction of diabetes, given their relative simplicity.

HOMA insulin sensitivity index and the risk of all-cause mortality and cardiovascular disease events in the general population : the Australian diabetes, obesity and lifestyle study (AusDiab) study

Aims/hypothesis We assessed whether the relationships between insulin sensitivity and all-cause mortality as well as fatal or non-fatal cardiovascular disease (CVD) events are independent of elevated blood glucose, high blood pressure, dyslipidaemia and body composition in individuals without diagnosed diabetes.
Methods Between 1999 and 2000, baseline fasting insulin, glucose and lipids, 2 h plasma glucose, HbA1c, anthropometrics, blood pressure, medication use, smoking and history of CVD were collected from 8,533 adults aged >35 years from the population-based Australian Diabetes, Obesity and Lifestyle study. Insulin sensitivity was estimated by HOMA of insulin sensitivity (HOMA-%S). Deaths and fatal or non-fatal CVD events were ascertained through linkage to the National Death Index and medical records adjudication.
Results After a median of 5.0 years there were 277 deaths and 225 CVD events. HOMA-%S was not associated with all-cause mortality. Compared with the most insulin-sensitive quintile, the combined fatal or non-fatal CVD HR (95% CI) for quintiles of decreasing HOMA-%S were 1.1 (0.6–1.9), 1.4 (0.9–2.3), 1.6 (1.0–2.5) and 2.0 (1.3–3.1), adjusting for age and sex. Smoking, CVD history, hypertension, lipid-lowering medication, total cholesterol and waist-to-hip ratio moderately attenuated this relationship. However, the association was rendered non-significant by adding HDL. Fasting plasma glucose, but not HOMA-%S significantly improved the prediction of CVD, beyond that seen with other risk factors.
Conclusions/interpretation In this cohort, HOMA-%S showed no association with all-cause mortality and only a modest association with CVD events, largely explained by its association with HDL. Fasting plasma glucose was a better predictor of CVD than HOMA-%S.

Screening for type 2 diabetes and impaired glucose metabolism – the Australian experience

OBJECTIVE--To assess the Australian protocol for identifying undiagnosed type 2 diabetes and impaired glucose metabolism.

RESEARCH DESIGN AND METHODS--The Australian screening protocol recommends a stepped approach to detecting undiagnosed type 2 diabetes based on assessment of risk status, measurement of fasting plasma glucose (FPG) in individuals at risk, and further testing according to FPG. The performance of and variations to this protocol were assessed in a population-based sample of 10,508 Australians.

RESULTS--The protocol had a sensitivity of 79.9%, specificity of 79.9%, and a positive predictive value (PPV) of 13.7% for detecting undiagnosed type 2 diabetes and sensitivity of 51.9% and specificity of 86.7% for detecting impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). To achieve these diagnostic rates, 20.7% of the Australian adult population would require an oral glucose tolerance test (OGTT). Increasing the FPG cut point to 6.1 mmol/l (110 mg/dl) or using Hb[A.sub.1c], instead of FPG to determine the need for an OGTT in people with risk factors reduced sensitivity, increased specificity and PPV, and reduced the proportion requiring an OGTT. However, each of these protocol variations substantially reduced the detection of IGT or IFG.

CONCLUSIONS--The Australian screening protocol identified one new case of diabetes for every 32 people screened, with 4 of 10 people screened requiring FPG measurement and 1 in 5 requiring an OGTT. In addition, 1 in 11 people screened had IGT or IFG. Including Hb[A.sub.1c] measurement substantially reduced both the number requiring an OGTT and the detection of IGT or IFG.

HbA1c as a screening tool for detection of type 2 diabetes: A systematic review

Aim: To assess the validity of glycated haemoglobin A1c (HbA1c) as a screening tool for early detection of Type 2 diabetes.

Methods: Systematic review of primary cross-sectional studies of the accuracy of HbA1c for the detection of Type 2 diabetes using the oral glucose tolerance test as the reference standard and fasting plasma glucose as a comparison.

Results: Nine studies met the inclusion criteria. At certain cut-off points, HbA1c has slightly lower sensitivity than fasting plasma glucose (FPG) in detecting diabetes, but slightly higher specificity. For HbA1c at a Diabetes Control and Complications Trial and UK Prospective Diabetes Study comparable cut-off point of ≥ 6.1%, the sensitivity ranged from 78 to 81% and specificity 79 to 84%. For FPG at a cut-off point of ≥ 6.1 mmol/l, the sensitivity ranged from 48 to 64% and specificity from 94 to 98%. Both HbA1c and FPG have low sensitivity for the detection of impaired glucose tolerance (around 50%).

Conclusions: HbA1c and FPG are equally effective screening tools for the detection of Type 2 diabetes. The HbA1c cut-off point of > 6.1% was the recommended optimum cut-off point for HbA1c in most reviewed studies; however, there is an argument for population-specific cut-off points as optimum cut-offs vary by ethnic group, age, gender and population prevalence of diabetes. Previous studies have demonstrated that HbA1c has less intra-individual variation and better predicts both micro- and macrovascular complications. Although the current cost of HbA1c is higher than FPG, the additional benefits in predicting costly preventable clinical complications may make this a cost-effective choice.

Sociodemographic correlates of the increasing trend in prevalence of gestational diabetes mellitus in a large population of women between 1995 and 2005

OBJECTIVE—Gestational diabetes mellitus (GDM) is an increasingly prevalent risk factor for the development of type 2 diabetes in the mother and is  responsible for morbidity in the child. To better identify women at risk of developing GDM we examined sociodemographic correlates and changes in the prevalence of GDM among all births between 1995 and 2005 in Australia's largest state.
RESEARCH DESIGN AND METHODS—A computerized database of all births (n = 956,738) between 1995 and 2005 in New South Wales, Australia, was used in a multivariate logistic regression that examined the association between sociodemographic characteristics and the occurrence of GDM.
RESULTS—Between 1995 and 2005, the prevalence of GDM increased by 45%, from 3.0 to 4.4%. Women born in South Asia had the highest adjusted odds ratio (OR) of any region (4.33 [95% CI 4.12–4.55]) relative to women born in Australia. Women living in the three lowest socioeconomic quartiles had higher adjusted ORs for GDM relative to women in the highest quartile (1.54 [1.50–1.59], 1.74 [1.69–1.8], and 1.65 [1.60–1.70] for decreasing socioeconomic status quartiles). Increasing age was strongly associated with GDM, with women aged >40 years having an adjusted OR of 6.13 (95% CI 5.79–6.49) relative to women in their early 20s. Parity was associated with a small reduced risk. There was no association between smoking and GDM.
CONCLUSIONS—Maternal age, socioeconomic position, and ethnicity are important correlates of GDM. Future culturally specific interventions should target prevention of GDM in these high-risk groups.

Vitamin C and the risk of gestational diabetes mellitus: a case-control study

OBJECTIVE: To examine whether low maternal dietary intake of vitamin C and low maternal plasma ascorbic acid (AA) concentrations are associated with an increased risk of gestational diabetes mellitus (GDM).
METHODS: Cases were 67 women with GDM meeting National Diabetes Data Group criteria. Controls were 260 women without such a diagnosis. Maternal dietary vitamin C consumption during the periconceptional period and during pregnancy was assessed using a 121-item, semiquantitative food frequency questionnaire. Maternal plasma AA concentrations were determined using automated enzymatic procedures on specimens collected during the intrapartum period.
RESULTS: Mean maternal daily consumption of vitamin C and plasma AA concentrations were 10% and 31% lower, respectively, among GDM cases as compared with controls (130.7 +/- 10.2 vs. 145 +/- 4.9 mg/d, P = .190; 36 +/- 2.0 vs. 53 +/- 1.0 micromol/L, P <.001). After controlling for maternal age, race, prepregnancy adiposity, family history of type 2 diabetes, energy intake and income, women reporting low daily vitamin C intake (< 70 mg/d), as compared with the other women, experienced a 3.7-fold increased risk of GDM (odds ratio [OR] = 3.7, 95% confidence interval [CI] 1.7-8.2). There was a linear relation in risk of GDM with decreasing concentrations of plasma AA (P for linear trend <.001). After adjusting for confounders, women in the lowest quartile (< 42.6 micromol/L), as compared with women in the highest quartile (> 63.3 micromol/L), experienced > 12-fold increased risk of GDM (OR = 12.8, 95% CI 3.5-46.2). CONCLUSION: Low maternal dietary vitamin C intake and low plasma AA concentrations are associated with an increased risk of GDM. Large, prospective, cohort studies are needed to further evaluate the potential beneficial role of vitamin C and other antioxidants in the prevention of impaired glucose tolerance in pregnancy.

Maternal plasma ascorbic acid (vitamin C) and risk of gestational diabetes mellitus

Background : Antioxidants, particularly vitamin C (ascorbic acid), have the capacity to influence glucose tolerance. Modification of diet could reduce the likelihood of developing gestational diabetes mellitus.

Methods : In a prospective cohort study of pregnant women, we studied the association of maternal plasma ascorbic acid concentrations, measured at an average of 13 weeks' gestation, with subsequent risk of gestational diabetes. Maternal plasma ascorbic acid concentrations were determined using automated enzymatic procedures. Dietary vitamin C intake during the periconceptional period and early pregnancy was ascertained using a semiquantitative food frequency questionnaire. We fitted generalized linear models to derive estimates of relative risks and 95% confidence intervals (CIs).

Results : Approximately 4% (n = 33) of 755 women who completed pregnancy developed gestational diabetes mellitus. Plasma ascorbic acid concentrations were inversely associated with the risk of gestational diabetes (P for trend = 0.023). After adjusting for maternal age, race, prepregnancy adiposity, parity, family history of type 2 diabetes, and household income, women with plasma ascorbic acid <55.9 micromol/L (lowest quartile) experienced a 3.1-fold increased risk of gestational diabetes (95% CI = 1.0 - 9.7) compared with women whose concentrations were > or = 74.6 micromol/L (upper quartile). Women who consumed <70 mg vitamin C daily experienced a 1.8-fold increased risk of gestational diabetes compared with women who consumed higher amounts (95% CI = 0.8 - 4.4).

Conclusions : If confirmed, our results raise the possibility that current efforts to encourage populations to consume diets rich in antioxidants, including vitamin C, could reduce the occurrence of gestational diabetes mellitus.

Liver fat metabolism, obesity and diabetes in Psammomys obesis

Defects in fat metabolism are central to the aetiology and pathogenesis of obesity and type II diabetes. The liver plays a central role in these disease states via its regulation of glucose and fat metabolism. In addition, accumulation of fat within the liver has been associated with changes in key pathways of carbohydrate and fat metabolism. However a number of questions remain. It is hypothesised that fat accumulation within the liver is a primary defect in the aetiology and pathogenesis of obesity and type II diabetes. Fat accumulating in the liver is the result of changes in the gene expression of key enzymes and proteins involved with fat uptake, fat transport, fat oxidation, fat re-esterification or storage and export of fat from the liver and these changes are regulated by key lipid responsive transcription factors. To study these questions Psammomys obesus was utilised. This polygenic rodent model of obesity and type II diabetes develops obesity and diabetes in a similar pattern to susceptible human populations. In addition dietary and environmental changes to Psammomys obesus were employed to create different states of energy balance, which allowed the regulation of liver fat gene expression to be examined. These investigations include: 1) Measurement of fat accumulation and fatty acid binding proteins in lean, obese and diabetic Psammomys obesus. 2) Characterisation of hepatic lipid enzymes, transport protein and lipid responsive transcription factor gene expression in lean, obese and diabetic Paammomys obesus. 3) The effect of acute and chronic energy restriction on hepatic lipid metabolism in Psammomys obesus. 4) The effect of sucrose feeding on the development of obesity and type II diabetes in Psammomys obesus. 5) The effect of nicotine treatment in lean and obese Psammomys obesus, 6) The effect of high dose leptin administration on hepatic fat metabolism in Psammomys obesus. The results of these studies demonstrated that fat accumulation within the liver was not a primary defect in the aetiology and pathogenesis of obesity and type II diabetes. Fat accumulating in the liver was not the result of changes in the gene expression of key enzymes and proteins involved in hepatic fat metabolism. However changes in the mRNA level of the transcription factors PPAR∝ and SREBP-1C was associated with the development of diabetes and the gene expression of these two transcription factors was associated with changes in diabetic status.

From rural beginnings to statewide roll-out : evaluation of facilitator training for a group-based diabetes prevention program

Objective: To evaluate the approach used to train facilitators for a large-scale group-based diabetes prevention program developed from a rural implementation research project.

Participants: Orientation day was attended by 224 health professionals; 188 submitted the self-learning task; 175 achieved the satisfactory standard for the self-learning task and attended the workshop; 156 completed the pre- and post-training questionnaires.

Main outcome measures: Two pre- and post-training scales were developed to assess knowledge and confidence in group-based diabetes prevention program facilitation. Principal component analysis found four factors for measuring training effectiveness: knowledge of diabetes prevention, knowledge of group facilitation, confidence to facilitate a group to improve health literacy and confidence in diabetes prevention program facilitation. Self-learning task scores, training discontinuation rates and satisfaction scores were also assessed.

Results: There was significant improvement in all four knowledge and confidence factors from pre- to post-training (P < 0.001). The self-learning task mean test score was 88.7/100 (SD = 7.7), and mean assignment score was 72.8/100 (SD = 16.1). Satisfaction with training scores were positive and 'previous training' interacted with 'change in knowledge of diabetes prevention program facilitation' but not with change in 'confidence to facilitate.'

Conclusions: The training program was effective when analysed by change in facilitator knowledge and confidence and the positive mean satisfaction score. Learning task scores suggest tasks were manageable and the requirement contributed to facilitator self-selection. Improvement in confidence scores in facilitating a group-based diabetes prevention program, irrespective of previous training and experience, show that program-specific skill development activities are necessary in curriculum design.

Practice nurses' role and knowledge about diabetes management within rural and remote Australian general practices

Background: The increasing prevalence of diabetes and obesity represents a significant disease burden in Australia. Practice nurses (PNs) play an important role in diabetes education and management.

Aim: To explore PNs' roles, knowledge and beliefs about diabetes education and management in rural and remote general practice in Australia.

Method: Exploratory study undertaken in three phases: 1) Pilot study to test the performance of the questionnaire; 2) One-shot cross-sectional survey using self-complete questionnaires; 3) Individual interviews.

Results: Ten PNs completed the pilot test; the draft questionnaire was deemed appropriate to the study purpose. Then, 65 questionnaires were distributed to PNs and 21 responded. Fourteen respondents had worked in the role <5 years, and most PNs attended diabetes education programmes in their workplace. A minority (40%) used diabetes management guidelines regularly. Most knew obesity to be the most common risk factor for diabetes but only 50% knew that glycosylated haemoglobin indicates blood glucose levels over the preceding three months. Self-reported competency to assess patients' self-care practices and medication management practices varied.

Conclusion: PNs' diabetes management was self-reported; their knowledge varied and their perceived benefits of diabetes education differed from those of patients.

Diabetes risk reduction behaviours of rural postpartum women with a recent history of gestational diabetes

Introduction: For most women, gestational diabetes is temporary; however, an episode of gestational diabetes mellitus (GDM) confers an approximately seven-fold increased risk of developing type 2 diabetes mellitus. Objective: To examine readiness to adopt diabetes risk reduction behaviours and the prevalence of these behaviours among rural women with GDM during their last pregnancy.
Methods: The study design was a self-administered mailed questionnaire seeking information about demographics, stage of change, physical activity level and dietary fat intake. Setting: Regional outpatient context. Participants: Women with a single episode of GDM between 1 July 2001 and 31 December 2005 (n = 210). Main outcome measures: Stage of change for physical activity, weight loss and reducing dietary fat behaviour; meeting activity targets, body mass index (BMI) and dietary fat score.
Results: Eighty-four women returned completed questionnaires (40% response rate). Of the 77 women eligible (mean age 35 ± 3.8 years), 58% met recommended activity targets. Sixty-three percent of women were overweight or obese: mean BMI 29.6 kg/m2 (± 7.30). Women reported a high level of preparedness to engage in physical activity, weight loss and reduction of fat intake. Thirty-nine percent of women had not had any postpartum follow-up glucose screening. Women who remembered receiving diabetes prevention information were significantly more likely to meet physical activity targets (p<0.05).
Conclusions: Readiness to engage in behaviour change was high among this group of rural women for all three diabetes risk reduction behaviours measured. However, despite a high proportion of women meeting activity targets and reducing fat intake, the majority of women remained overweight or obese. Postpartum follow-up glucose testing needs to be improved and the impact of diabetes prevention information provided during pregnancy warrants further study.

TGF-Ý signalling in human skeletal muscle regeneration and diabetes

The TGF-Ý superfamily comprises a large group of proteins with many effects on muscle growth and maturation. The molecular regulation of skeletal muscle regeneration and metabolism in response to prominent superfamily members, myostatin and TGF-Ý1, were analysed, demonstrating the importance of this pathway in controlling how muscles grow and are regulated.

Oxygen (O2) kinetics during early recovery from peak exercise in patients with type 2 diabetes

Aims To examine the oxygen (O₂) kinetics during early recovery from peak exercise in patients with Type 2 diabetes and to examine whether oxygen O₂ recovery is associated with fasting glucose and HbA_1c in this population.

Methods Eighty-nine participants (52 men) aged 51.8 ± 7.1 years (mean ± sd) were divided into three groups: normal weight (BMI ≤ 25.0 kg/m²), overweight/obese without diabetes (BMI ≥ 26 kg/m²) and overweight/obese with Type 2 diabetes. Participants were assessed for their aerobic power (VO_2peak) on a cycle ergometer, provided a fasting blood sample and underwent a series of anthropometric measurements. Early recovery period was measured for 60 s from cessation of exercise and expressed as percentage of VO_2peak (higher percentage represents slower recovery).

Results No significant differences were observed for age between the three study groups. Both the overweight/obese groups without diabetes and with Type 2 diabetes had higher BMI than the normal weight group, with no significant differences between overweight/obese participants without diabetes and those with diabetes. Participants with Type 2 diabetes had lower VO_2peak than overweight/obese participants without diabetes and normal weight individuals (19.6 ± 4.8, 22.6 ± 5.4 and 25.7 ± 5.3 ml kg⁻¹ min⁻¹, respectively, P < 0.004 for overall trends). Participants with Type 2 diabetes also had slower recovery in oxygen O₂ kinetics after exercise, compared with both normal weight and overweight/obese individuals without diabetes (56.5 ± 7.7, 49.2 ± 7.2, 47.7 ± 7.4%, P < 0.004 for overall trends). Multiple regression analysis revealed that percentage of oxygen O₂ recovery was a stronger predictor than VO_2peak, BMI or age for fasting glucose and HbA_1c.

Conclusions Patients with Type 2 diabetes have lower VO_2peak and prolonged oxygen O₂ recovery from peak exercise. However, only prolonged oxygen O₂ recovery was associated with fasting glucose and HbA_1c.