Preventing type 2 diabetes using combination therapy: design and methods of the CAnadian Normoglycaemia Outcomes Evaluation (CANOE) trial

Diabetes awareness and diabetes risk reduction behaviors among attendance of primary healthcare centers

AIMS

The aims of this study were to assess level of awareness about diabetes and the level of adoption of diabetes risk behaviors among adult attending primary healthcare centers.

METHODS

A cross-sectional descriptive study was conducted using a self-administrated questionnaire. In addition to demographic information, the questionnaire contained questions on diabetes awareness related to diabetes definition, symptoms, risk factors, complications and management of diabetes as well as questions on diabetes risk reduction behaviors and sources of information on diabetes. The data was analyzed with independent t-test, Pearson's correlation coefficient, and ANOVA test.

RESULTS

A total of 541 participants aged ≥ 18 years were recruited. The mean score of diabetes awareness was 27.5/40 [SD=5.7]. The participants performed best in symptoms section with a mean score of 6.3/8 [SD=1.6], and worst in the risk factors section with a mean score of 3.6/6 (SD=1.4). With respect to diabetes risk reduction behaviors the results showed that the highest mean score was for fat reduction 2.0/4 [SD=0.8]; and the lowest mean score was for weight control or losing 1.7/4 [SD=0.8].

CONCLUSIONS

The current study demonstrated that substantial numbers of adult Jordanian lack the sufficient awareness about diabetes to prevent and cope with the increasing prevalence of diabetes in Jordan. Also, it demonstrated that adoption of diabetes risk reduction behaviors was suboptimal. Raising public awareness of diabetes and diabetes risk reduction behaviors through population-based programs and mass media should be planned and implemented.

Changes in dietary habits and their association with metabolic markers after a non-intensive, community-based lifestyle intervention to prevent type 2 diabetes, in Greece. The DEPLAN study

AIMS

The aim of the present study was to evaluate the impact on dietary and activity habits of a non-intensive, community based lifestyle intervention for type 2 diabetes prevention, in high-risk Greek individuals.

METHODS

A total of 191 high-risk persons were invited to participate in a one-year lifestyle intervention program, consisting of six bi-monthly sessions with a dietician. The dietary aims of the intervention were: reduction of saturated fat, sugars and refined cereals intake and at least five servings of fruits and vegetables, daily. Demographic, dietary, anthropometric, medical and biochemical indices were recorded at baseline and at the end of the intervention.

RESULTS

The intervention was completed by 126 participants. At study end, participants reported decreased whole fat dairies and processed meats consumption (p=0.018 and 0.016, respectively), sugars (p=0.006) and refined cereals (p=0.045). Participants who improved their diet, decreased body weight (p=0.040), plasma triglycerides (p=0.020) and 2-h post-load plasma glucose (p=0.05) compared to those who had worsened their dietary habits. Total time spent daily on physical activity, remained unchanged throughout the intervention.

CONCLUSIONS

The implementation of a group-based, non-intensive dietary counseling proved to be practical and feasible in "real-world" community settings and was accompanied by favorable dietary changes and health benefits.

Discordant effects on central obesity, hepatic insulin resistance, and alanine aminotransferase of low-dose metformin and thiazolidinedione combination therapy in patients with impaired glucose tolerance

Alanine aminotransferase (ALT) predicts incident type 2 diabetes (T2DM), possibly reflecting early fatty liver and hepatic insulin resistance. Thiazolidinediones and metformin can improve fatty liver and hepatic insulin resistance, respectively. In the Canadian Normoglycemia Outcome Evaluation trial, rosiglitazone/metformin (Rosi/Met, 4/1000 mg) reduced incident T2DM by 66% in subjects with impaired glucose tolerance. For insight on the hepatic effects of this therapy in relation to T2DM, we evaluated the temporal changes in waist, hepatic insulin sensitivity (1/Homeostasis Model Assessment of Insulin Resistance) and ALT in the Rosi/Met (n = 103) and placebo (n = 104) arms over median of 3.9 years. Waist did not differ between the arms. Hepatic insulin sensitivity improved in the Rosi/Met arm in year 1, but deteriorated thereafter as in the placebo arm. In contrast, Rosi/Met lowered ALT in year 1 and maintained this effect throughout the trial. Thus, low-dose Rosi/Met had no effect on central obesity, a transient effect on hepatic insulin sensitivity, and a sustained effect on ALT.

Changes over time in glycemic control, insulin sensitivity, and beta-cell function in response to low-dose metformin and thiazolidinedione combination therapy in patients with impaired glucose tolerance

OBJECTIVE

In the Canadian Normoglycemia Outcome Evaluation (CANOE) trial, low-dose rosiglitazone/metformin reduced the risk of diabetes in subjects with impaired glucose tolerance by 66% over a median of 3.9 years. We evaluate the temporal changes in glycemic control, insulin sensitivity, and β-cell function during this trial.

RESEARCH DESIGN AND METHODS

CANOE participants (n=207) underwent annual oral glucose tolerance testing, enabling temporal comparison of glycemia, insulin sensitivity (Matsuda index), and β-cell function (insulin secretion-sensitivity index-2 [ISSI-2]) between the rosiglitazone/metformin and placebo arms.

RESULTS

Glycemic parameters and insulin sensitivity improved in the rosiglitazone/metformin arm in year 1, but deteriorated in the years thereafter as in the placebo arm. Generalized estimating equation analysis confirmed that both insulin sensitivity and β-cell function decreased over time (Matsuda: β=-0.0515, P<0.0001; ISSI-2: β=-6.6507, P<0.0001), with no significant time-by-treatment interaction (Matsuda: P=0.57; ISSI-2: P=0.22).

CONCLUSIONS

Despite preventing incident diabetes, low-dose rosiglitazone/metformin did not modify the natural history of worsening insulin resistance and β-cell dysfunction.

The effects of metformin with lifestyle therapy in polycystic ovary syndrome: a randomized double-blind study

OBJECTIVE

To determine if the combination of lifestyle (caloric restriction and exercise) and metformin (MET) would be superior to lifestyle and placebo (PBO) in improving the polycystic ovary syndrome (PCOS) phenotype.

DESIGN

Double-blind randomized 6-month trial of MET versus PBO.

SETTING

Two academic medical centers.

PATIENT(S)

One hundred fourteen subjects with PCOS were randomized to MET (N = 55) or PBO (N = 59).

INTERVENTION(S)

Subjects collected urine daily for ovulation monitoring, had monthly monitoring of hormones and weight and determination of body composition by dual-energy x-ray absorptiometry, glucose tolerance, and were evaluated for quality of life at baseline and completion.

MAIN OUTCOME MEASURE(S)

Ovulation rates and testosterone levels.

RESULT(S)

Dropout rates were high. There was no significant difference in ovulation rates. Testosterone levels were significantly lower compared with baseline in the MET group at 3 mos but not at 6 mos. There were no differences in weight loss between groups, but MET showed a significant decline at 6 months compared with baseline (-3.4 kg, 95% confidence interval -5.3 to -1.5 kg). We noted divergent effects of MET versus PBO on oral glucose tolerance test indices of insulin sensitivity (increased) and secretion (worsened). Total bone mineral density increased significantly in MET. There were no differences in quality of life measures between the groups. The MET group had increased diarrhea and headache, but fewer bladder infections and musculoskeletal complaints.

CONCLUSION(S)

The addition of metformin to lifestyle therapy produced little reproductive or glycemic benefit in women with PCOS, although our study had limited power owing to a high dropout rate. It is not possible at baseline to identify women likely to drop out.

Diabetes awareness in general population in Cameroon

BACKGROUND

A good knowledge about diabetes could lead to early diagnosis and improved management.

OBJECTIVE

To evaluate the level of diabetes awareness in Cameroonians, and to identify factors that influence this awareness.

METHODS

In subjects aged ≥ 25 years (n=1000, 93.4% of response), details regarding risk factors, symptoms, treatment and complications of type 2 diabetes were collected. One mark was attributed to each true answer and a global diabetes awareness score was computed. Influence of age, gender, educational level, occupational level, notion of a relative having a chronic condition and presence of chronic disease were analyzed.

RESULTS

Eighty percent of subjects scored more than the total mean score. The highest score obtained by participants (0.10%) was 28/30. The mean total score was higher in men (p < 0.02) and in subjects with a relative having a chronic condition (p < 0.001). In multivariate analyses, age classes (p < 0.01), educational level (p < 0.001) and relatives with a chronic condition (p < 0.001) were associated to the global diabetes awareness score.

CONCLUSIONS

Diabetes awareness was generally good. This may be due to the fact that the study was conducted in an area where health promotion and health education on diabetes have been intensively delivered for the past 4 years.

Low-dose combination therapy with rosiglitazone and metformin to prevent type 2 diabetes mellitus (CANOE trial): a double-blind randomised controlled study

BACKGROUND

The evolving epidemic of type 2 diabetes has challenged health-care providers to assess the safety and efficacy of various diabetes prevention strategies. The CANOE (CAnadian Normoglycemia Outcomes Evaluation) trial investigated whether low-dose combination therapy would affect development of type 2 diabetes.

METHODS

In this double-blind, randomised controlled trial undertaken in clinics in Canadian centres, 207 patients with impaired glucose tolerance were randomly assigned to receive combination rosiglitazone (2 mg) and metformin (500 mg) twice daily or matching placebo for a median of 3.9 years (IQR 3.0-4.6). Randomisation was computer-generated in blocks of four, with both participants and investigators masked to treatment allocation. The primary outcome was time to development of diabetes, measured by an oral glucose tolerance test or two fasting plasma glucose values of 7.0 mmol/L or greater. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00116932.

FINDINGS

103 participants were assigned to rosiglitazone and metformin, and 104 to placebo; all were analysed. Vital status was obtained in 198 (96%) participants, and medication compliance (taking at least 80% of assigned medication) was 78% (n=77) in the metformin and rosiglitazone group and 81% (n=80) in the placebo group. Incident diabetes occurred in significantly fewer individuals in the active treatment group (n=14 [14%]) than in the placebo group (n=41 [39%]; p<0.0001). The relative risk reduction was 66% (95% CI 41-80) and the absolute risk reduction was 26% (14-37), yielding a number needed to treat of 4 (2.70-7.14). 70 (80%) patients in the treatment group regressed to normal glucose tolerance compared with 52 (53%) in the placebo group (p=0.0002). Insulin sensitivity decreased by study end in the placebo group (median -1.24, IQR -2.38 to -0.08) and remained unchanged with rosiglitazone and metformin treatment (-0.39, -1.30 to 0.84; p=0.0006 between groups). The change in beta-cell function, as measured by the insulin secretion-sensitivity index-2, did not differ between groups (placebo -252.3, -382.2 to -58.0 vs rosiglitazone and metformin -221.8, -330.4 to -87.8; p=0.28). We recorded an increase in diarrhoea in participants in the active treatment group compared with the placebo group (16 [16%] vs 6 [6%]; p=0.0253).

INTERPRETATION

Low-dose combination therapy with rosiglitazone and metformin was highly effective in prevention of type 2 diabetes in patients with impaired glucose tolerance, with little effect on the clinically relevant adverse events of these two drugs.

FUNDING

GlaxoSmithKline.

Association of hematological parameters with insulin resistance and beta-cell dysfunction in nondiabetic subjects

OBJECTIVE

Previous studies reported independent associations of hematological parameters with risk of incident type 2 diabetes, although limited data are available on associations of these parameters with insulin resistance (IR) and (especially) pancreatic beta-cell dysfunction in large epidemiological studies. Our objective was to evaluate the associations of hematological parameters, including hematocrit (HCT), hemoglobin (Hgb), red blood cell count (RBC), and white blood cell count with IR and beta-cell dysfunction in a cohort of nondiabetic subjects at high metabolic risk.

METHODS

Nondiabetic subjects (n = 712) were recruited in Toronto and London, Ontario, Canada, between 2004 and 2006, based on the presence of one or more risk factors for type 2 diabetes mellitus including obesity, hypertension, a family history of diabetes, and/or a history of gestational diabetes. Fasting blood samples were collected and oral glucose tolerance tests administered, with additional samples for glucose and insulin drawn at 30 and 120 min. Measures of IR included the homeostasis model assessment (HOMA-IR) and Matsuda's insulin sensitivity index, whereas measures of beta-cell dysfunction included the insulinogenic index divided by HOMA-IR as well as the insulin secretion-sensitivity index-2. Associations of hematological parameters with IR and beta-cell dysfunction were assessed using multiple linear regression and analysis of covariance with adjustments for age, gender, ethnicity, smoking, cardiovascular disease, systolic and diastolic blood pressure, and waist circumference.

RESULTS

HOMA-IR increased across quartiles of HCT, Hgb, RBC, and white blood cell count after adjustment for age, gender, ethnicity, and smoking (all P (trend) <0.0001). Similarly, there was a strong stepwise decrease in the Matsuda's insulin sensitivity index across increasing quartiles of these hematological measures (all P (trend) <0.0001). The associations remained significant after further adjustment for previous cardiovascular disease, blood pressure, and waist circumference (all P (trend) <0.0001). Similarly, there was a strong pattern of decreasing beta-cell function across increasing quartiles of all hematological patterns (all P (trend) <0.0001). The findings for HCT, Hgb, and RBC were attenuated slightly after full multivariate adjustment, although the trend across quartiles remained highly significant.

CONCLUSION

These findings suggest that standard, clinically relevant hematological variables may be related to the underlying pathophysiological changes associated with type 2 diabetes mellitus.

Hyperbolic relationship between insulin secretion and sensitivity on oral glucose tolerance test

The utility of the disposition index as a measure of beta-cell compensatory capacity rests on the established hyperbolic relationship between its component insulin secretion and sensitivity measures as derived from the intravenous glucose tolerance test (IVGTT). If one is to derive an analogous measure of beta-cell compensation from the oral glucose tolerance test (OGTT), it is thus necessary to first establish the existence of this hyperbolic relationship between OGTT-based measures of insulin secretion and insulin sensitivity. In this context, we tested five OGTT-based measures of secretion (insulinogenic index, Stumvoll first phase, Stumvoll second phase, ratio of total area-under-the-insulin-curve to area-under-the-glucose-curve (AUC(ins/gluc)), and incremental AUC(ins/gluc)) with two measures of sensitivity (Matsuda index and 1/Homeostasis Model of Assessment for insulin resistance (HOMA-IR)). Using a model of log(secretion measure) = constant + beta x log(sensitivity measure), a hyperbolic relationship can be established if beta is approximately equal to -1, with 95% confidence interval (CI) excluding 0. In 277 women with normal glucose tolerance (NGT), the pairing of total AUC(ins/gluc) and Matsuda index was the only combination that satisfied these criteria (beta = -0.99, 95% CI (-1.66, -0.33)). This pairing also satisfied hyperbolic criteria in 53 women with impaired glucose tolerance (IGT) (beta = -1.02, (-1.72, -0.32)). In a separate data set, this pairing yielded distinct hyperbolae for NGT (n = 245) (beta = -0.99, (-1.67, -0.32)), IGT (n = 116) (beta = -1.18, (-1.84, -0.53)), and diabetes (n = 43) (beta = -1.37, (-2.46, -0.29)). Moreover, the product of AUC(ins/gluc) and Matsuda index progressively decreased from NGT (212) to IGT (193) to diabetes (104) (P < 0.001), consistent with declining beta-cell function. In summary, a hyperbolic relationship can be demonstrated between OGTT-derived AUC(ins/gluc) and Matsuda index across a range of glucose tolerance. Based on these findings, the product of these two indices emerges as a potential OGTT-based measure of beta-cell function.

Knowledge and perceptions of diabetes in a semi-urban Omani population

Background

Diabetes mellitus is a major public health problem in the Sultanate of Oman. This study aimed to evaluate the knowledge and perception of diabetes in a sample of the Omani general population, and the associations between the elements of knowledge and perception, and socio-demographic factors.

Methods

The study was carried out in two semi-urban localities. A total of 563 adult residents were interviewed, using a questionnaire specifically designed for the present study. In addition to demographic information, the questionnaire contained questions on knowledge related to diabetes definition, symptoms, risk factors, complications and preventative measures, as well as risk perception for diabetes.

Results

Knowledge of diabetes was suboptimal. The percentages of correct responses to questions on diabetes definition, classical symptoms, and complications were 46.5%, 57.0%, and 55.1%, respectively. Only 29.5%, 20.8% and 16.9% identified obesity, physical inactivity and a positive family history, respectively, as risk factors for diabetes. A higher level of education, a higher household income, and the presence of a family history of diabetes were found to be positively associated with more knowledge.

Conclusion

This study demonstrated that there is lack of awareness of major risk factors for diabetes mellitus. Level of education is the most significant predictor of knowledge regarding risk factors, complications and the prevention of diabetes. Given that the prevalence of diabetes has increased drastically in Oman over the last decade, health promotion seems essential, along with other means to prevent and control this emerging health problem.

Prevention of type 2 diabetes: an update

With the rising tide of the diabetes epidemic leading to increased morbidity and mortality (primarily from cardiovascular disease), together with failure to control the disease and its associated complications, prevention of diabetes appears to be the logical option for curbing this epidemic. Several trials have been completed, and others ongoing, using various strategies for diabetes prevention. In this review, we provide an update on diabetes prevention strategies, highlighting the rationale behind such interventions, together with an outlook of the ongoing efforts that are likely to provide additional options for patients at risk for diabetes.

Antidiabetic agents in subjects with mild dysglycaemia: prevention or early treatment of type 2 diabetes?

Besides lifestyle, various pharmacological treatments have proven their efficacy to reduce the incidence of type 2 diabetes in high-risk individuals, especially in those with impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG). Major placebo-controlled clinical trials demonstrated favourable effects of various glucose-lowering drugs generally used for the treatment of type 2 diabetes, i.e. metformin, acarbose and thiazolidinediones (glitazones). These trials showed a lower rate of progression to overt diabetes and a higher regression rate to a normal glucose status with active treatment as compared to placebo after a follow up of several years. Ongoing trials should confirm such a favourable effect with those drugs and may demonstrate a similar protective effect with other pharmacological approaches such as glinides or even basal insulin regimen. However, the reported favourable effects were generally observed while the subjects were still on treatment, and partially vanished after a rather short period of wash-out of several weeks. Therefore, the distinction between a true preventing effect and simply a masking effect is difficult with glucose-lowering drugs. In addition, as type 2 diabetes is a progressive disease, it is still questionable whether the effect corresponds to a prevention effect or only to a postponing of the development of the disease. Owing to the pathophysiology of the disease, the only way to block the progression of type 2 diabetes is probably to avoid the progressive loss of beta-cell function and/or mass. Whatsoever, these data obtained in large clinical trials bring further argument to support early treatment of diabetes, even at a prediabetic state, in order to stop the vicious circle leading to an inevitable deterioration of glycaemia in predisposed subjects.

A Conceptual Framework for Targeting Prediabetes with Lifestyle, Clinical, And Behavioral Management Interventions

Prediabetes is a condition that does not fall squarely into the primary or secondary prevention domain, and therefore tends to be inadequately addressed by interventions in either health promotion or disease management. Prediabetes is defined as having an impaired fasting glucose (fasting glucose of 100-125 mg/dL), impaired glucose tolerance (two-hour postprandial glucose of 140-199 mg/dL), or both. There is substantial evidence to suggest that even at these blood glucose levels, significant risk exists for both microand macrovascular complications. This paper introduces a conceptual framework of care for prediabetes that includes both screening and the provision of up-to-date clinical therapies in conjunction with an evidence-based health coaching intervention. In combination, these modalities represent the most effective means for delaying or even preventing the onset of diabetes in a prediabetes population. This paper concludes with a brief example in which these principles are applied to a hypothetical patient.