Early recognition and treatment of glucose abnormalities to prevent type 2 diabetes mellitus and coronary heart disease

Predictive and explanatory factors of cardiovascular disease in people with adequately controlled type 2 diabetes

Aims To explore the predictive and explanatory factors on the incidence of cardiovascular disease and the impact of visit-to-visit variability (VVV) of risk factors on incident cardiovascular disease in people with type 2 diabetes with no history of prior cardiovascular disease. Methods We performed a historical cohort study (2008-2011) on 481 people with type 2 diabetes and no history of cardiovascular disease. Cardiovascular risk factors were assessed at baseline and repeatedly during follow-up. The predictive analysis included the variables at enrollment, and explanatory analyses were based on mean of the variables measured repeatedly. VVV of the main variables was measured using the standard deviation and coefficient of variation of the measured variables. Separate multivariate binary logistic models were constructed for each parameter with the incident cardiovascular disease. Results Mean age of the participants was 54.9 years, mean glycated hemoglobin was 56 mmol/mol, and mean blood pressure was 125/78 mmHg. Incident cardiovascular disease developed in 14.3% of the participants. The 2-h post breakfast blood glucose was associated with incident cardiovascular disease (odds ratio 1.44; confidence interval = 1.08-1.90; p = 0.01). For each 1 mmol/l increase in postprandial glucose there was a 44% increase in risk of incident cardiovascular disease. VVV of glycemic indices, blood pressure, lipids, body mass index and creatinine were not associated with occurrence of cardiovascular events. Conclusion In this population of patients with type 2 diabetes and no history of cardiovascular disease in whom other cardiovascular risk factors are within or near to the recommended targets, 2-h post breakfast blood glucose level is associated with incident cardiovascular disease.

WITHDRAWN: Dietary advice for the prevention of type 2 diabetes mellitus in adults

Review status was set to withdrawn. The review is out of date and does not meet current Cochrane standards. It will be superseded by a new expanding Cochrane review on 'Diet, physical activity or both for the prevention or delay of type 2 diabetes mellitus and its associated complications in persons at increased risk'.

The editorial group responsible for this previously published document have withdrawn it from publication.

Dietary advice for the prevention of type 2 diabetes mellitus in adults

BACKGROUND

Prevention of type 2 diabetes in adults is a far better option than treatment, to alleviate pressure on health care providers and resources. However, there is no current review of the evidence regarding the efficacy of a diet-only intervention for prevention.

OBJECTIVES

To assess the effects of type and frequency of dietary advice for the prevention of type 2 diabetes mellitus.

SEARCH STRATEGY

We carried out a comprehensive search of The Cochrane Library, MEDLINE, EMBASE, CINAHL, AMED, bibliographies and contacted relevant experts.

SELECTION CRITERIA

All randomised controlled trials, of twelve months or longer, in which dietary advice for the prevention of type 2 diabetes was the only intervention in adults.

DATA COLLECTION AND ANALYSIS

The lead investigator performed all data extraction and quality scoring with duplication being carried out by one of the other four investigators independently with discrepancies resolved by discussion and consensus. Authors were contacted for missing data. Change data are presented.

MAIN RESULTS

Two trials which randomised 358 people to dietary treatment and control groups were identified. Longest duration of follow-up was six years. In the 6-year Da Qing IGT & Diabetes study, the incidence of type 2 diabetes in the control group was 67.7% (95% confidence interval (CI) 59.8% to 75.2%) which was reduced to 43.8% (95% CI 35.5% to 54.7%) in the diet group. Overall, the dietary intervention group had a 33% reduction in the incidence of diabetes after six years (P < 0.03). The Oslo Diet & Exercise Study (ODES) found significant (P<0.05) reductions in insulin resistance, fasting insulin (pmol/L), fasting C-peptide (pmol/L), fasting proinsulin (pmol/L), fasting blood glucose (mmol/L), BMI (kg/m(2)), mBP (mmHg) and fasting triglycerides (mmol/L), and a significant increase in fasting HDL cholesterol (mmol/L) and PAI-1 (U/ml) after 12 months of dietary intervention. Data on mortality, morbidity, health-related quality of life, adverse effects, costs were not reported in either study.

AUTHORS' CONCLUSIONS

There are no high quality data on the efficacy of dietary intervention for the prevention of type 2 diabetes. More well-designed, long-term studies, providing well-reported, high-quality data are required before proper conclusions can be made into the best dietary advice for the prevention of diabetes mellitus in adults.

Psychological predictors of physical activity in the diabetes prevention program

OBJECTIVE

To identify the baseline psychological variables before receiving a Diabetes Prevention Program (DPP) lifestyle intervention that predict physical activity levels (PALs) at baseline, 1 year, and end of study (2 to 3 years after randomization).

DESIGN AND SUBJECTS

Of the final 293 DPP lifestyle participants randomized, 274 (94%) completed validated questionnaires at baseline assessing stage of change for PAL, exercise self-efficacy, perceived stress, depression, and anxiety.

STATISTICAL ANALYSES PERFORMED

Correlations and stepwise multiple regression analyses.

RESULTS

At baseline, this subset was similar to the entire DPP lifestyle cohort: mean age was 52.5 years, 65% were women, and mean PAL was 15.7 metabolic equivalent hours per week. Higher levels of baseline leisure PAL correlated with greater readiness to change PAL (r=0.44, P<0.0001), higher exercise self-efficacy (r=0.18, P=0.002), and lower levels of perceived stress (r=-0.16, P=0.009), depression (r=-0.18, P=0.003), and anxiety (r=-0.14, P=0.03), with similar correlations at 1 year and end of study. In multivariate models, being a man, lower levels of depression, and lower body mass index were independent correlates of higher baseline leisure PAL; being a man, greater baseline exercise self-efficacy, and activity level were independent correlates of greater leisure PAL levels at 1 year and end of study. Greater readiness to change PAL at baseline was also an independent correlate of greater PAL at end of study.

CONCLUSIONS

In this representative sample of DPP lifestyle participants, being a man, lower body mass index, greater readiness for change in PAL, higher exercise self-efficacy, and lower perceived stress, depression, and anxiety scores correlated with higher levels of baseline PAL with similar patterns at 1 year and end of study. These findings may help determine which patients are most likely to increase PAL in lifestyle intervention programs.

Use of glucose, insulin, and C-reactive protein to determine need for glucose tolerance testing

OBJECTIVE

Glucose intolerance has been shown to be a better predictor of morbidity and mortality than impaired fasting glucose. However, glucose tolerance tests are inconvenient and expensive. This study evaluated the relative frequencies of glucose intolerance and impaired fasting glucose and sought to determine if 2-hour glucose could be predicted from simple demographic and laboratory data in an obese population.

RESEARCH METHODS AND PROCEDURES

Eighty-nine obese subjects (median BMI 35 kg/m(2), range 30 to 40 kg/m(2)) underwent glucose tolerance testing. Using step-wise linear and logistic regression analysis, fasting glucose, high-sensitivity C-reactive protein (hsCRP), fasting insulin, high-density lipoprotein cholesterol, triglycerides, weight, height, BMI, waist circumference, hip circumference, waist-to-hip ratio, sex, and age were assessed as predictors of glucose intolerance.

RESULTS

Impaired glucose tolerance was more prevalent (27%) than impaired fasting glucose (5.6%). Only fasting glucose and hsCRP were significant (p < 0.05) independent predictors of impaired 2-hour glucose (>140 mg/dL). A fasting glucose > or =100 mg/dL or an hsCRP > 0.32 mg/dL (upper quartile of the normal range) detected 81% (sensitivity) of obese subjects with impaired glucose tolerance; however, specificity was poor (46%). Fasting insulin > or =6 micro U/mL had better sensitivity (92%) but poorer specificity (30%).

DISCUSSION

Impaired glucose tolerance is more common than impaired fasting glucose in an obese population. Possible strategies to avoid doing glucose tolerance tests in all obese patients would be to do glucose tolerance testing only in those whose fasting glucose is > or =100 mg/dL or whose hsCRP exceeds 0.32 mg/dL or those whose fasting insulin is > or =6 micro U/mL.

Prediabetes mellitus and its links to atherosclerosis

Type 2 diabetes mellitus is a chronic insidious process contributing to an overwhelming amount of morbidity and mortality, much of which is related to atherosclerosis, which often accompanies and complicates the natural history of diabetes. Although considerable attention has focused on new insights into diabetic mechanisms and emerging treatments, perhaps one of the greatest opportunities for decreasing the toll of diabetes and its late-stage complications may be intervening earlier in the disease process. Such notions redirect attention toward the concept of prediabetes mellitus as a potentially discrete syndrome, which may be identifiable in clinical practice. This article seeks to offer support for this hypothesis by considering the data surrounding prediabetes mellitus, with particular attention on the mechanistic and clinical links to atherosclerosis.

Impaired glucose tolerance and impaired fasting glycaemia: the current status on definition and intervention

A workshop was convened by the International Diabetes Federation to review the latest information relating to the risks associated with impaired glucose tolerance (IGT) and impaired fasting glycaemia (IFG) for future diabetes and cardiovascular disease (CVD). The workshop sought to address three questions: (i) are the current definitions of IGT and IFG appropriate; (ii) are IFG and IGT risk factors, risk markers or diseases; (iii) what interventions (if any) should be recommended for people with IFG and IGT? The determinants of elevated fasting glucose and 2-h plasma glucose in an oral glucose tolerance test (2-HPG) levels differ. Raised hepatic glucose output and a defect in early insulin secretion are characteristic of the former, and peripheral insulin resistance is most characteristic of the latter. Therefore, it is not surprising that the concordance between the categories of IFG and IGT is limited. In all prevalence studies to date only half or less of people with IFG have IGT, and even a lower proportion (20-30%) with IGT also have IFG. In the majority of populations studied, IGT is more prevalent than IFG, and there is a difference in phenotype and gender distribution between the two categories. IFG is substantially more common amongst men and IGT slightly more common amongst women. The prevalence of IFG tends to plateau in middle age whereas the prevalence of IGT rises into old age. Both IFG and IGT are associated with a substantially increased risk of developing diabetes, with the highest risk in people with combined IFG and IGT. Because IGT is commoner than IFG in most populations it is more sensitive (but slightly less specific) for identifying people who will develop diabetes. In most populations studied, 60% of people who develop diabetes have either IGT or IFG 5 years or so before, with the other 40% having normal glucose tolerance at that time. The limited published data suggest that both isolated IFG (I-IFG) and isolated IGT (I-IGT) are similarly associated with cardiovascular risk factors, such as hypertension and dyslipidaemia, with the highest risk in those with combined IFG and IGT. However, some data have suggested that I-IGT is more strongly associated with hypertension and dyslipidaemia (features of the metabolic syndrome) than I-IFG. In unadjusted analyses both IFG and IGT are associated with CVD and total mortality. In separate analyses for fasting and 2-HPG adjusted for other cardiovascular risk factors (from the DECODE study) there remains a continuous relationship between 2-HPG and mortality, but an independent relationship with fasting glucose is only found above 7.0 mmol/l. Glycated haemoglobin (HbA1c) levels are continuously and positively associated with CVD and total mortality independent of other CVD risk factors. Life style interventions, including weight loss and increased physical activity, are highly effective in preventing or delaying the onset of diabetes in people with IGT. Two randomized controlled trials of individuals with IGT found that life style intervention studies reduce the risk of progressing to diabetes by 58%. The oral hypoglycaemic drugs metformin and acarbose have also been shown to be effective, but less so than the life style measures. Similar data do not yet exist for the effectiveness of such interventions in people with I-IFG. Larger studies are required to evaluate the effects of interventions on cardiovascular outcomes in people with IGT. Cost effective strategies to identify people with IGT for intervention should be developed and evaluated. The use of simple risk scores to assess who should undergo an oral glucose tolerance test is one promising approach, although these will need to be population-specific. In conclusion, IGT and IFG differ in their prevalence, population distribution, phenotype, and risk of total mortality and CVD. The consensus of the workshop was: 1. The diagnostic thresholds for all categories of glucose intolerance should be revisited in the light of the latest evidence. There was no clear consensus (with current evidence) on whether IFG and IGT should be classified as diseases, but they clearly represent risk factors and risk markers for diabetes and CVD, respectively. 2. Both IGT and IFG are similarly associated with an increased risk of diabetes, but IGT is more strongly associated with CVD outcomes. 3. Risks are higher when IGT and IFG coexist. 4. Life style interventions are highly effective in delaying or preventing the onset of diabetes in people with IGT and may reduce CVD and total mortality, but the latter requires formal testing.