Impact of lifestyle intervention and metformin on health-related quality of life: the diabetes prevention program randomized trial.

BACKGROUND: Adults at high risk for diabetes may have reduced health-related quality of life (HRQoL). OBJECTIVE: To assess changes in HRQoL after interventions aimed at diabetes risk reduction. DESIGN, SETTING, AND PARTICIPANTS: A randomized clinical trial, the Diabetes Prevention Program, was conducted in 27 centers in the United States, in 3,234 non-diabetic persons with elevated fasting and post-load plasma glucose, mean age 51 years, mean BMI 34 Kg/m(2); 68 % women, and 45 % members of minority groups. INTERVENTIONS: Intensive lifestyle (ILS) program with the goals of at least 7 % weight loss and 150 min of physical activity per week, metformin (MET) 850 mg twice daily, or placebo (PLB). MEASUREMENTS: HRQoL using the 36-Item Short-Form (SF-36) health survey to evaluate health utility index (SF-6D), physical component summaries (PCS) and mental component summaries (MCS). A minimally important difference (MID) was met when the mean of HRQoL scores between groups differed by at least 3 %. RESULTS: After a mean follow-up of 3.2 years, there were significant improvements in the SF-6D (+0.008, p=0.04) and PCS (+1.57, p<0.0001) scores in ILS but not in MET participants (+0.002 and +0.15, respectively, p=0.6) compared to the PLB group. ILS participants showed improvements in general health (+3.2, p<0.001), physical function (+3.6, p<0.001), bodily pain (+1.9, p=0.01), and vitality (+2.1, p=0.01) domain scores. Treatment effects remained significant after adjusting sequentially for baseline demographic factors, and for medical and psychological comorbidities. Increased physical activity and weight reduction mediated these ILS treatment effects. Participants who experienced weight gain had significant worsening on the same HRQoL specific domains when compared to those that had treatment-related (ILS or MET) weight loss. No benefits with ILS or MET were observed in the MCS score. CONCLUSION: Overweight/obese adults at high risk for diabetes show small improvement in most physical HRQoL and vitality scores through the weight loss and increased physical activity achieved with an ILS intervention.

Evaluation of a novel isotope biomarker for dietary consumption of sweets.

Carbon isotopic signatures ("δ¹³C") might reflect consumption of corn- and cane-based sweeteners. The authors hypothesized that the δ¹³C value of human serum is higher for individuals with high versus low intakes of corn- and cane-based sweeteners (measured as sweetened beverage intake). They conducted a cross-sectional study within the Atherosclerosis Risk in Communities Magnetic Resonance Imaging study (Maryland, 2005-2006). Diet was assessed by food frequency questionnaire, and blinded serum samples were assayed by natural abundance stable isotope mass spectroscopy. Studied were 186 participants (53% male; mean age, 71 years; mean body mass index, 30 kg/m²). Serum δ¹³C values for individuals with high sweetened beverage intakes were significantly higher than for those with low intakes (-19.15‰ vs. -19.47‰, P < 0.001). Serum δ¹³C value increased 0.20‰ for every serving/day of sweetened beverages (P < 0.01). The association between sweetened beverages and serum δ¹³C value remained significant after adjustment for confounding by corn-based product intake (P < 0.001). Serum δ¹³C values were also associated with waist circumference, body mass index, and waist-to-hip ratio. This study provides the first known evidence that the δ¹³C value of human serum differs between persons consuming low and high amounts of sweets. Within the proper framework, serum δ¹³C value could be developed into an objective biomarker promoting more reliable assessment of dietary sweets intake.

A randomized comparison of the terms estimated average glucose versus hemoglobin A1C.

PURPOSE: The purpose of this study was to evaluate the hypothesis that using estimated average glucose (eAG) while instructing patients yields better knowledge retention than using the term hemoglobin A1C (A1C). METHODS: Patients with diabetes who had poor baseline understanding of A1C (determined by a 4-question survey) were randomized into 1 of 2 groups: A1C or eAG. Depending on randomization, providers discussed patients' current status and personal targets for glycemic control using either the term A1C or estimated average glucose. Patients had a telephone survey 3-4 weeks later, assessing change in knowledge of glycemic control. RESULTS: The 80 participants who completed follow-up had similar baseline characteristics, including poor understanding of A1C and poor recall of previous A1C values. At the 3-4 week follow-up, average score for each survey question improved significantly in both groups, with mean composite score increasing in the A1C group by 32% and in the eAG group by 33%. There was no suggestion of a difference in degree of improvement between groups. CONCLUSIONS: Patients previously unfamiliar with the meaning of A1C, using either term (A1C or eAG) resulted in an equal improvement in knowledge. Within this study, eAG was not a more understandable term, or an easier concept for patients to remember. Further research is needed to test whether use of the term A1C should be replaced by eAG.

A new look at screening and diagnosing diabetes mellitus.

OBJECTIVE: Diabetes is underdiagnosed. About one third of people with diabetes do not know they have it, and the average lag between onset and diagnosis is 7 yr. This report reconsiders the criteria for diagnosing diabetes and recommends screening criteria to make case finding easier for clinicians and patients. PARTICIPANTS: R.M.B. invited experts in the area of diagnosis, monitoring, and management of diabetes to form a panel to review the literature and develop consensus regarding the screening and diagnosis of diabetes with particular reference to the use of hemoglobin A1c (HbA1c). Participants met in open session and by E-mail thereafter. Metrika, Inc. sponsored the meeting. EVIDENCE: A literature search was performed using standard search engines. CONSENSUS PROCESS: The panel heard each member's discussion of the issues, reviewing evidence prior to drafting conclusions. Principal conclusions were agreed on, and then specific cut points were discussed in an iterative consensus process. CONCLUSIONS: The main factors in support of using HbA1c as a screening and diagnostic test include: 1) HbA1c does not require patients to be fasting; 2) HbA1c reflects longer-term glycemia than does plasma glucose; 3) HbA1c laboratory methods are now well standardized and reliable; and 4) errors caused by nonglycemic factors affecting HbA1c such as hemoglobinopathies are infrequent and can be minimized by confirming the diagnosis of diabetes with a plasma glucose (PG)-specific test. Specific recommendations include: 1) screening standards should be established that prompt further testing and closer follow-up, including fasting PG of 100 mg/dl or greater, random PG of 130 mg/dl or greater, or HbA1c greater than 6.0%; 2) HbA1c of 6.5-6.9% or greater, confirmed by a PG-specific test (fasting plasma glucose or oral glucose tolerance test), should establish the diagnosis of diabetes; and 3) HbA1c of 7% or greater, confirmed by another HbA1c- or a PG-specific test (fasting plasma glucose or oral glucose tolerance test) should establish the diagnosis of diabetes. The recommendations are offered for consideration of the clinical community and interested associations and societies.

Therapeutic potential of dipeptidyl peptidase-IV inhibitors in patients with diabetes mellitus.

Dipeptidyl peptidase-IV (DPP-IV) inhibitors are a new class of oral antidiabetic agents for the treatment of patients with type 2 diabetes. Inhibition of the enzyme DPP-IV results in increased activity of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), the incretin hormones. Through the action of GLP-1 and GIP, DPP-IV inhibitors improve preprandial and postprandial glucose by enhancing insulin secretion and reducing postprandial concentrations of glucagon. This review examines the background, current evidence, and future therapeutic potential of this novel class of drug.

Implantable insulin pump therapy: an unusual presentation of a catheter-related complication.

We report the case of a 63-year-old man who has a 19-year history of involvement in the implantable insulin pump program at Johns Hopkins University. After his most recent pump implantation in February 2004, his 24-h insulin requirement gradually increased from a baseline of 75 units to a peak of almost 500 units in June 2005. Surprisingly, insulin delivery from the pump and glycemic control remained satisfactory despite the dramatic change in insulin requirement. Laparotomy revealed a fibrous mass in the peritoneal cavity, with the track of the catheter extending into the mass. Insulin requirement declined post-resection of the mass and relocation of the catheter tip.

Glucose levels in the normal range predict incident diabetes in families with premature coronary heart disease.

PURPOSE: Little is known about excess risk of incident diabetes conferred by fasting plasma glucose (FPG) within the normal range (<5.6 mmol/l) for high risk families. METHODS: Healthy 30-59 year old non-diabetic siblings (N = 542) of index cases with documented premature coronary disease were followed prospectively for type 2 diabetes. RESULTS: During 8.7+/-3 years of follow-up, incident diabetes was identified in 7.8%. Rates were incremental with baseline non-diabetes FPG thresholds of 5.0, 5.6, 6.1, and 6.7 mmol/l (p for trend < 0.0001). FPG was the strongest predictor of incident diabetes even across levels within the normal range. The multivariable adjusted relative risk was 14.9 (95% CI = 3.4-65.2) at FPG thresholds > or =5.0 mmol/l versus FPG <5.0 mmol/l. The maximal diagnostic efficiency for FPG was 5.50 mmol/l; with sensitivity and specificity 0.782. All FPG thresholds in the normal range between 5.0 and 5.6 mmol/l showed efficiency levels >0.74. The overall area under the ROC curve predicting incident diabetes for normal and prediabetes ranges of FPG was 0.867. CONCLUSION: Higher FPG levels within the designated "normal" range in high risk families are a potent independent risk factor for type 2 diabetes and may serve as a sentinel to trigger primary preventive interventions.

Assessing glycemia in diabetes using self-monitoring blood glucose and hemoglobin A1c.

CONTEXT: With the increasing prevalence of diabetes, successful management of blood glucose control is increasingly important. Current approaches to assessing glycemia include the use of self-monitoring of blood glucose (SMBG) and hemoglobin A1c (HbA1c). OBJECTIVES: To assess the evidence underlying the use of these 2 modalities, to evaluate confounders and sources of error in each test, to describe upcoming developments, and to reach evidence-based conclusions on their optimal use. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION: Reports identified from MEDLINE searches (1976-2005) using relevant terms were selected for quality and relevance to the stated questions. Particular attention was paid to larger cohort studies, clinical trials, meta-analyses, and established recommendations. DATA SYNTHESIS: If used properly SMBG gives an acceptably accurate reflection of immediate plasma glucose levels. Study results vary, but in general, the evidence supports a positive effect of regular SMBG for improving glycemia, particularly in individuals treated with insulin. The best timing of SMBG and its frequency are controversial issues, but the clinical recommendation is for regular monitoring with frequency depending on the treatment and the instability of glycemia. In the relatively near term, SMBG could gradually be replaced by continuous glucose monitoring. HbA1c measures long-term glycemic control, reflecting a time-weighted mean over the previous 3 to 4 months. There are a number of physiologic and methodologic confounders that can affect HbA1c, but standardization of assays has been well established. The main value of HbA1c is its use as a predictor of diabetic complications and the proven effect of improved control of HbA1c on complication risk. A reasonable target value for HbA1c is less than 7%. A new method for measuring HbA1c may cause significant changes in the recommended levels, the numbers reported, and even the name of the test. CONCLUSION: Assessing glycemia in diabetes can be a challenge, but approaches are available that promote successful management of blood glucose and may thereby lead to a significant reduction in morbidity and mortality related to diabetes.

Timing of changes in interstitial and venous blood glucose measured with a continuous subcutaneous glucose sensor.

The objective of this study was to use a subcutaneous continuous glucose sensor to determine time differences in the dynamics of blood glucose and interstitial glucose. A total of 14 patients with type 1 diabetes each had two sensors (Medtronic/MiniMed CGMS) placed subcutaneously in the abdomen, acquiring data every 5 min. Blood glucose was sampled every 5 min for 8 h, and two liquid meals were given. A smoothing algorithm was applied to the blood glucose and interstitial glucose curves. The first derivatives of the glucose traces defined and quantified the timing of rises, peaks, falls, and nadirs. Altogether, 24 datasets were used for the analysis of time differences between interstitial and blood glucose and between sensors in each patient. Time differences between blood and interstitial glucose ranged from 4 to 10 min, with the interstitial glucose lagging behind blood glucose in 81% of cases (95% CIs 72.5 and 89.5%). The mean (+/-SD) difference between the two sensors in each patient was 6.7 +/- 5.1 min, representing random variation in sensor response. In conclusion, there is a time lag of interstitial glucose behind blood glucose, regardless of whether glycemia is rising or falling, but intersensor variability is considerable in this sensor system. Comparisons of interstitial and blood glucose kinetics must take statistical account of variability between sensors.

Is HbA(1c) affected by glycemic instability?

OBJECTIVE: HbA(1c) is a standard clinical assessment of glycemia and the basis of most data relating glycemic control to complications. It remains unclear, however, whether HbA(1c) is affected by glycemic variation and mean glycemia. RESEARCH DESIGN AND METHODS: To test this question, we analyzed the statistical relationship between HbA(1c) levels and glycemic variability as measured by self-monitoring of blood glucose (SMBG). The records of 256 subjects were studied. SMBG data for the preceding 3 months were downloaded, and HbA(1c) was measured by ion-exchange high-performance liquid chromatography. Simple- and random-effects linear regression models were used to assess the independent contributions of mean blood glucose (BG) and SD of BG to HbA(1c), after adjusting for the mean BG. RESULTS: Mean +/- SD for HbA(1c) was 7.66 +/- 1.11% and for BG was 8.5 +/- 1.9 mmol/l (153.3 +/- 34.9 mg/dl); SD of BG for individual subjects was 3.5 mmol/l (63.3 mg/dl), varying from 0.4 mmol/l (8.1 mg/dl; very stable glycemia) to 8.4 mmol/l (152.5 mg/dl; very unstable glycemia). A close correlation between mean BG and HbA(1c) was demonstrated (r = 0.62). Also, within-subject SD of BG correlated with HbA(1c) (r = 0.375), indicating that people with poorer glycemic control had higher BG variance. After adjusting for mean BG in a linear regression model, however, the effect of the within-subject SD of BG on the HbA(1c) was insignificant. Several further analyses confirmed the strength of the observation. CONCLUSIONS: HbA(1c) reflects mean glycemia and is not meaningfully affected by glycemic instability after adjusting for mean BG.

Preventable hospitalization among elderly Medicare beneficiaries with type 2 diabetes.

OBJECTIVE: To examine the impact of comorbid conditions on preventable hospitalizations among Medicare beneficiaries aged > or =65 years with type 2 diabetes. RESEARCH DESIGN AND METHODS: Data were drawn from the 1999 Medicare Standard Analytic Files, a 5% nationally representative random sample of Medicare beneficiaries. The analysis sample included 193,556 Medicare beneficiaries aged > or =65 years with type 2 diabetes (ICD-9-CM codes 250.xx) who were enrolled in fee-for-service Medicare. Preventable hospitalization was assessed by measuring ambulatory care-sensitive conditions, an accepted measure of hospitalizations that could have been prevented with appropriate outpatient care. Multivariable analyses controlled for demographics; mortality; renal, ophthalmic, or neurological manifestations of diabetes; type of physician providing the outpatient care; and per capita community-level indicators of income and hospital beds. RESULTS: Ninety-six percent of beneficiaries in the sample had a comorbidity, and 46% had five or more comorbidities. Among beneficiaries with type 2 diabetes, cardiovascular-related comorbidities were common and accounted for increased odds of preventable hospitalization, controlling for other factors. The likelihood of a preventable hospitalization increased in the presence of a claim for comorbid congestive heart failure, cardiomyopathy, coronary atherosclerosis, hypertension, or cardiac dysrythmias. Noncardiovascular comorbidities associated with a greater likelihood of preventable hospitalization included chronic obstructive pulmonary disease, asthma and lower respiratory disorders, Alzheimer's disease/dementia, personality/anxiety disorders, depression, and osteoporosis. Our data suggest that nearly 7% of all hospitalizations could be avoided. CONCLUSIONS: These findings support the need for improved outpatient care strategies to reduce the impact of comorbidity on unnecessary hospitalization in patients aged > or =65 years with type 2 diabetes.

The diagnosis of fasting hypoglycemia due to an islet-cell tumor obscured by a highly specific insulin assay.

The work-up of fasting hypoglycemia may be difficult but is crucially important because a wrong diagnosis can lead to either unnecessary pancreatectomy or a missed pancreatic tumor. We describe a patient with severe fasting hypoglycemia [22-32 mg/dl (1.2-1.8 mmol/liter) after 6-10 h of fasting] in which the diagnosis of a secretory islet-cell tumor was obscured, rather than facilitated, by use of a new, highly specific serum insulin assay. Insulin measured by the specific assay suppressed normally during fasting hypoglycemia [undetectable at < 2.0-3.8 micro IU/ml (26.4 pmol/liter)], whereas insulin measured by older, less specific assays was diagnostically elevated [34, 73 micro IU/ml (236.1, 507.0 pmol/liter)]. Serum proinsulin and C-peptide levels were abnormal, and further work-up revealed an islet-cell tumor that secreted predominantly proinsulin. The tumor was surgically removed, relieving the fasting hypoglycemia. We conclude that insulin levels as measured by new, highly specific insulin assays may obscure the diagnosis of a functional, proinsulin-secreting islet-cell tumor. Because proinsulin cross-reacts with insulin in older insulin assays, C-peptide or proinsulin should be measured to rule out a proinsulin-secreting islet-cell tumor. Normative values for new insulin assays must be established during prolonged fasting.

Effectiveness and cost-effectiveness of diabetes prevention among adherent participants.

OBJECTIVES: We report the 10-year effectiveness and within-trial cost-effectiveness of the Diabetes Prevention Program (DPP) and its Outcomes Study (DPPOS) interventions among participants who were adherent to the interventions. STUDY DESIGN: DPP was a 3-year randomized clinical trial followed by 7 years of open-label modified intervention follow-up. METHODS: Data on resource utilization, cost, and quality of life were collected prospectively. Economic analyses were performed from health system and societal perspectives. Lifestyle adherence was defined as achieving and maintaining a 5% reduction in initial body weight, and metformin adherence as taking metformin at 80% of study visits. RESULTS: The relative risk reduction was 49.4% among adherent lifestyle participants and 20.8% among adherent metformin participants compared with placebo. Over 10 years, the cumulative, undiscounted, per capita direct medical costs of the interventions, as implemented during the DPP, were greater for adherent lifestyle participants ($4810) than adherent metformin participants ($2934) or placebo ($768). Over 10 years, the cumulative, per capita non-interventionrelated direct medical costs were $4250 greater for placebo participants compared with adherent lifestyle participants and $3251 greater compared with adherent metformin participants. The cumulative quality-adjusted life-years (QALYs) accrued over 10 years were greater for lifestyle (6.80) than metformin (6.74) or placebo (6.67). Without discounting, from a modified societal perspective (excluding participant time) and a full societal perspective (including participant time), lifestyle cost < $5000 per QALY-gained and metformin was cost saving compared with placebo. CONCLUSIONS: Over 10 years, lifestyle intervention and metformin were cost-effective or cost saving compared with placebo. These analyses confirm that lifestyle and metformin represent a good value for money.

Glucose and insulin measurements from the oral glucose tolerance test and relationship to muscle mass.

BACKGROUND: Diabetes is associated with decreased muscle mass. The effect of higher levels of glucose and insulin on muscle mass has not been studied in individuals without diabetes. We sought to determine the relationship of insulin and glucose measurements from the oral glucose tolerance test (OGTT) with muscle mass in persons without diabetes. METHODS: We analyzed data from 587 participants in the Baltimore Longitudinal Study of Aging (mean age 67.3 years, range 26-95 years) without diabetes who underwent a 2-hour OGTT, including glucose and insulin measurements taken every 20 minutes and assessment of midthigh muscle cross-sectional area by computed tomography, taken as a proxy measure of muscle mass. Linear regression models and Bayesian model averaging were used to explore the independent cross-sectional association of various OGTT-derived measures and midthigh muscle cross-sectional area, independent of confounders. RESULTS: Individually, fasting glucose, fasting insulin, OGTT glucose (40, 60, 80, 100, and 120 minutes), OGTT insulin (20, 60, 80, 100, and 120 minutes), homeostasis model assessment of insulin resistance, integrated glucose area, and integrated insulin area were inversely associated, and the Matsuda index was positively associated, with the midthigh muscle cross-sectional area (standardized to body weight) after adjustment for age, sex, race, height, physical activity, and peroneal motor nerve conduction velocity (all ps <.05). When considered together, the Matsuda index and fasting glucose were the strongest predictors of lower midthigh muscle cross-sectional area after covariate adjustment. CONCLUSIONS: Higher fasting and OGTT values of both glucose and insulin are associated with lower muscle mass. Longitudinal studies are needed to verify whether individuals free of diabetes that have higher glucose and insulin during an OGTT are at risk for accelerated muscle mass decline with aging.

Parental longevity and diabetes risk in the Diabetes Prevention Program.

BACKGROUND: Longevity clusters in families, and parental longevity may be associated with lower risk of chronic diseases in their children. It is unknown if diabetes risk is associated with parental longevity. METHODS: We evaluated participants in the Diabetes Prevention Program with a parental history questionnaire at study entry. We classified them into five groups: premature death (parental death at age < 50 years), parental longevity (living to at least 80 years), and three intermediate groups (alive by age 49 but dying at age 50-59, 60-69, or 70-79). Those with alive parents and younger than 80 years were excluded. We analyzed separately effects of paternal (n = 2,165) and maternal (n = 1,739) longevity on diabetes incidence and risk after an average follow-up of 3.2 years. RESULTS: At baseline, more diabetes risk factors (parental history of diabetes, coronary heart disease, higher body mass index, homeostasis model assessment for insulin resistance, and corrected insulin response) were found in participants whose parents died prematurely. Diabetes incidence was 9.5 cases/100 person-years in the 229 whose fathers died prematurely. In the 618 with paternal longevity, the rate was 6.6 cases/100 person-years (hazard ratio [95% confidence interval] = 0.68 [0.49-0.94]). The rates were 10.7 cases/100 person-years (n = 156) and 7.3 cases/100 person-years (n = 699, hazard ratio = 0.67 [95% confidence interval 0.47-0.95]) for those with maternal premature death or longevity, respectively. Associations with demographic and diabetes risk factors had minimal influence on the reduced risk found in those with paternal (adjusted hazard ratio = 0.78, 95% confidence interval 0.52-1.16) and maternal (adjusted hazard ratio = 0.64, 95% confidence interval 0.41-1.01) longevity. CONCLUSION: Parental longevity is associated with lower diabetes incidence in adults at high risk of type 2 diabetes.

Increased expression of beta-N-acetylglucosaminidase in erythrocytes from individuals with pre-diabetes and diabetes.

OBJECTIVE: O-linked beta-N-acetylglucosamine (O-GlcNAc) plays an important role in the development of insulin resistance and glucose toxicity. O-GlcNAcylation is regulated by O-GlcNAc transferase (OGT), which attaches O-GlcNAc to serine and/or threonine residues of proteins and by O-GlcNAcase, which removes O-GlcNAc. We investigated the expression of these two enzymes in erythrocytes of human subjects with diabetes or pre-diabetes. RESEARCH DESIGN AND METHODS: Volunteers with normal condition, pre-diabetes, and diabetes were recruited through a National Institutes of Health (National Institute of Diabetes and Digestive and Kidney Diseases) study and at the Johns Hopkins Comprehensive Diabetes Center. Erythrocyte proteins were extracted and hemoglobins were depleted. Global O-GlcNAcylation of erythrocyte proteins was confirmed by Western blotting using an O-GlcNAc-specific antibody. Relative OGT and O-GlcNAcase protein amounts were determined by Western blot analysis. Relative expression of O-GlcNAcase was compared with the level of A1C. RESULTS: Erythrocyte proteins are highly O-GlcNAcylated. O-GlcNAcase expression is significantly increased in erythrocytes from both individuals with pre-diabetes and diabetes compared with normal control subjects. Unlike O-GlcNAcase, protein levels of OGT did not show significant changes. CONCLUSIONS: O-GlcNAcase expression is increased in erythrocytes from both individuals with pre-diabetes and individuals with less well-controlled diabetes. These findings, together with the previous study that demonstrated the increased site-specific O-GlcNAcylation of certain erythrocyte proteins, suggest that the upregulation of O-GlcNAcase might be an adaptive response to hyperglycemia-induced increases in O-GlcNAcylation, which are likely deleterious to erythrocyte functions. In any case, the early and substantial upregulation of O-GlcNAcase in individuals with pre-diabetes may eventually have diagnostic utility.