Intensive Glucose Control in Patients with Type 2 Diabetes - 15-Year Follow-up.

BACKGROUND: We previously reported that a median of 5.6 years of intensive as compared with standard glucose lowering in 1791 military veterans with type 2 diabetes resulted in a risk of major cardiovascular events that was significantly lower (by 17%) after a total of 10 years of combined intervention and observational follow-up. We now report the full 15-year follow-up. METHODS: We observationally followed enrolled participants (complete cohort) after the conclusion of the original clinical trial by using central databases to identify cardiovascular events, hospitalizations, and deaths. Participants were asked whether they would be willing to provide additional data by means of surveys and chart reviews (survey cohort). The prespecified primary outcome was a composite of major cardiovascular events, including nonfatal myocardial infarction, nonfatal stroke, new or worsening congestive heart failure, amputation for ischemic gangrene, and death from cardiovascular causes. Death from any cause was a prespecified secondary outcome. RESULTS: There were 1655 participants in the complete cohort and 1391 in the survey cohort. During the trial (which originally enrolled 1791 participants), the separation of the glycated hemoglobin curves between the intensive-therapy group (892 participants) and the standard-therapy group (899 participants) averaged 1.5 percentage points, and this difference declined to 0.2 to 0.3 percentage points by 3 years after the trial ended. Over a period of 15 years of follow-up (active treatment plus post-trial observation), the risks of major cardiovascular events or death were not lower in the intensive-therapy group than in the standard-therapy group (hazard ratio for primary outcome, 0.91; 95% confidence interval [CI], 0.78 to 1.06; P = 0.23; hazard ratio for death, 1.02; 95% CI, 0.88 to 1.18). The risk of major cardiovascular disease outcomes was reduced, however, during an extended interval of separation of the glycated hemoglobin curves (hazard ratio, 0.83; 95% CI, 0.70 to 0.99), but this benefit did not continue after equalization of the glycated hemoglobin levels (hazard ratio, 1.26; 95% CI, 0.90 to 1.75). CONCLUSIONS: Participants with type 2 diabetes who had been randomly assigned to intensive glucose control for 5.6 years had a lower risk of cardiovascular events than those who received standard therapy only during the prolonged period in which the glycated hemoglobin curves were separated. There was no evidence of a legacy effect or a mortality benefit with intensive glucose control. (Funded by the VA Cooperative Studies Program; VADT ClinicalTrials.gov number, NCT00032487.).

Follow-up of glycemic control and cardiovascular outcomes in type 2 diabetes.

BACKGROUND: The Veterans Affairs Diabetes Trial previously showed that intensive glucose lowering, as compared with standard therapy, did not significantly reduce the rate of major cardiovascular events among 1791 military veterans (median follow-up, 5.6 years). We report the extended follow-up of the study participants. METHODS: After the conclusion of the clinical trial, we followed participants, using central databases to identify procedures, hospitalizations, and deaths (complete cohort, with follow-up data for 92.4% of participants). Most participants agreed to additional data collection by means of annual surveys and periodic chart reviews (survey cohort, with 77.7% follow-up). The primary outcome was the time to the first major cardiovascular event (heart attack, stroke, new or worsening congestive heart failure, amputation for ischemic gangrene, or cardiovascular-related death). Secondary outcomes were cardiovascular mortality and all-cause mortality. RESULTS: The difference in glycated hemoglobin levels between the intensive-therapy group and the standard-therapy group averaged 1.5 percentage points during the trial (median level, 6.9% vs. 8.4%) and declined to 0.2 to 0.3 percentage points by 3 years after the trial ended. Over a median follow-up of 9.8 years, the intensive-therapy group had a significantly lower risk of the primary outcome than did the standard-therapy group (hazard ratio, 0.83; 95% confidence interval [CI], 0.70 to 0.99; P=0.04), with an absolute reduction in risk of 8.6 major cardiovascular events per 1000 person-years, but did not have reduced cardiovascular mortality (hazard ratio, 0.88; 95% CI, 0.64 to 1.20; P=0.42). No reduction in total mortality was evident (hazard ratio in the intensive-therapy group, 1.05; 95% CI, 0.89 to 1.25; P=0.54; median follow-up, 11.8 years). CONCLUSIONS: After nearly 10 years of follow-up, patients with type 2 diabetes who had been randomly assigned to intensive glucose control for 5.6 years had 8.6 fewer major cardiovascular events per 1000 person-years than those assigned to standard therapy, but no improvement was seen in the rate of overall survival. (Funded by the VA Cooperative Studies Program and others; VADT ClinicalTrials.gov number, NCT00032487.).

Retinoblastoma protein co-purifies with proteasomal insulin-degrading enzyme: implications for cell proliferation control.

Previous investigations on proteasomal preparations containing insulin-degrading enzyme (IDE; EC 3.4.24.56) have invariably yielded a co-purifying protein with a molecular weight of about 110kDa. We have now found both in MCF-7 breast cancer and HepG2 hepatoma cells that this associated molecule is the retinoblastoma tumor suppressor protein (RB). Interestingly, the amount of RB in this protein complex seemed to be lower in HepG2 vs. MCF-7 cells, indicating a higher (cytoplasmic) protein turnover in the former vs. the latter cells. Moreover, immunofluorescence showed increased nuclear localization of RB in HepG2 vs. MCF-7 cells. Beyond these subtle differences between these distinct tumor cell types, our present study more generally suggests an interplay between RB and IDE within the proteasome that may have important growth-regulatory consequences.

Insulin metabolism in human adipocytes from subcutaneous and visceral depots.

Subjects with the metabolic syndrome (insulin resistance, glucose intolerance, dyslipidemia, hypertension, etc.) have a relative increase in abdominal fat tissue compared to normal individuals and obesity has also been shown to be associated with a decrease in insulin clearance. The majority of the clearance of insulin is due to the action of insulin-degrading enzyme (IDE) and IDE is present throughout all tissues. Since abdominal fat is increased in obesity we hypothesized that IDE may be altered in the different fat depots. Adipocytes were isolated from fat samples obtained from subjects during elective abdominal surgery. Fat samples were taken from subcutaneous (SQ) and visceral (VIS) sites. Insulin metabolism was compared in adipocytes isolated from SQ and VIS fat tissue. Adipocytes from the VIS site degraded more insulin that those from SQ fat tissue. Inhibitors of cathepsins B and D has no effect on the degradation of insulin, while bacitracin, an inhibitor of IDE, inhibited degradation by approx. 33% in both SQ and VIS adipocytes. These data show that insulin metabolism is relatively greater in VIS than in SQ fat tissue and potentially due to IDE.

Blood glucose monitoring is associated with better glycemic control in type 2 diabetes: a database study.

BACKGROUND: The value of self-monitoring blood glucose (SMBG) in type 2 diabetes is controversial. OBJECTIVE: To determine SMBG testing rates are positively associated with glycemic control in veterans on oral hypoglycemic agents (OHA). DESIGN: Observational database study. SUBJECTS: Southwestern Healthcare Network veterans taking OHA in 2002 and followed through the end of 2004. MEASUREMENTS: OHA and glucose test strip (GTS) prescriptions were derived from pharmacy files. Subjects were categorized into five groups according to their end-of-study treatment status: group 1 (no medication changes), group 2 (increased doses of initial OHA), group 3 (started new OHA), group 4 (both OHA interventions), and group 5 (initiated insulin). We then used multiple linear regression analyses to examine the relationship between the SMBG testing rate and hemoglobin A1c (HbA1c) within each group. RESULTS: We evaluated 5,862 patients with a mean follow-up duration of 798 +/- 94 days. Overall, 44.2% received GTS. Ultimately, 47% of subjects ended up in group 1, 21% in group 2, 9% in group 3, 8% in group 4, and 16% in group 5. A univariate analysis showed no association between the SMBG testing rate and HbA1c. However, after stratifying by group and adjusting for initial OHA dose, we found that more frequent testing was associated with a significantly lower HbA1c in groups 1, 4, and 5. The effect ranged from -0.22% to -0.94% for every ten GTS/week. CONCLUSIONS: Higher SMBG testing rates were associated with lower HbA1c, but only when stratifying the analyses to control for treatment intensification.

Regulation of protein degradation by insulin-degrading enzyme: analysis by small interfering RNA-mediated gene silencing.

Proteins are vital to the overall structure of cells and to the function of cells in the form of enzymes. Thus the control of protein metabolism is among the most important aspects of cellular metabolism. Insulin's major effect on protein metabolism in the adult animal is inhibition of protein degradation. This is via inhibition of proteasome activity via an interaction with insulin-degrading enzyme (IDE). IDE is responsible for the majority of cellular insulin degradation. We hypothesized that a reduction in IDE would reduce insulin degradation and insulin's ability to inhibit protein degradation. HepG2 cells were transfected with siRNA against human IDE and insulin degradation and protein degradation measured. Both IDE mRNA and protein were reduced by >50% in the IDE siRNA transfected cells. Insulin degradation was reduced by approximately 50%. Cells were labeled with [3H]-leucine to investigate protein degradation. Short-lived protein degradation was unchanged in the cells with reduced IDE expression. Long-lived and very-long-lived protein degradation was reduced in the cells with reduced IDE expression (14.0+/-0.16 vs. 12.5+/-0.07%/4h (long-lived), 9.6+/-2.2% vs. 7.3+/-0.2%/3h (very-long-lived), control vs. IDE transfected, respectively, P<0.005). The inhibition of protein degradation by insulin was reduced 37-76% by a decreased expression of IDE in HepG2 cells. This shows that IDE is involved in cellular insulin metabolism and provides further evidence that insulin inhibits protein degradation via an interaction with IDE.

Adoption of a new technology in a Veterans Affairs national formulary system with local implementation: the insulin glargine example.

A study group gathered by the Pharmacy & Therapeutics Society reviewed data on the Department of Veterans Affairs (VA) health care system's implementation of a new technology (insulin glargine) for patients with diabetes. It examined local implementation of VA criteria for nonformulary use of insulin glargine in 21 VA treatment facilities that were surveyed about the issue. The examination found differences in the use of insulin glargine across the 21 treatment facilities and in the approach to implementing the criteria for nonformulary use of insulin glargine used at the individual VA treatment facility level. Differences were identified regarding the respective roles of endocrinologists and PCPs in prescribing insulins, including insulin glargine. The study group urges further short- and long-term research to better understand the utilization, cost, and health outcome implications of the implementation process for the nonformulary criteria. Lessons learned from such research could benefit other health care systems and formulary committees.

Baseline achievement of lipid goals and usage of lipid medications in patients with diabetes mellitus (from the Veterans Affairs Diabetes Trial).

The American Diabetes Association has established lipid goals for patients with diabetes. Although diabetic populations historically have poor low-density lipoprotein (LDL) cholesterol goal adherence, little is known about adherence to triglyceride and high-density lipoprotein (HDL) cholesterol goals. To determine the degree of lipid goal attainment among patients with diabetes, and to characterize the patterns of lipid medication use, we evaluated the baseline data from 1,742 enrollees of the national Veterans Affairs Diabetes Trial. Using current American Diabetes Association lipid guidelines, we calculated the proportion of participants achieving a LDL cholesterol level <100 mg/dl, triglyceride level <150 mg/dl, and HDL cholesterol level >40 mg/dl in men (>50 mg/dl in women). We also performed a descriptive analysis of the use of lipid medications in this population. The baseline LDL cholesterol level was 111 +/- 63 mg/dl, triglyceride level was 213 +/- 277 mg/dl, and HDL cholesterol was 36 +/- 10 mg/dl. At enrollment, 44% of veterans met the LDL cholesterol goal, 58% met the triglyceride goal, and 16% met the HDL cholesterol goal, but only 6% met all 3 goals. Of the 1,742 enrollees, 2/3 were receiving lipid therapy, with statins (58%) the most commonly used drug. Combination lipid therapy was used by 11% of enrollees. Although the enrollees of the Veterans Affairs Diabetes Trial demonstrated better adherence to the American Diabetes Association's LDL cholesterol goal than other diabetic populations recently studied, more aggressive and directed lipid medication use is needed to treat the overall lipid profile better.

Control of cardiovascular risk factors in the Veterans Affairs Diabetes Trial in advanced type 2 diabetes.

OBJECTIVE: To present a status report on the Veterans Affairs Diabetes Trial (VADT), a multisite long-term study examining the effect of glucose control on cardiovascular (CV) complications in older patients with established, poorly controlled type 2 diabetes. METHODS: We review the rationale, objectives, and design of the VADT and summarize the baseline data and the results achieved thus far. RESULTS: The main objective of this 20-site, 1,792-patient study is to ascertain whether intensive glucose control can reduce major CV events in patients with difficult-to-control type 2 diabetes. The study design consists of a standard treatment arm and an intensive treatment arm, with a goal of 1.5% difference in hemoglobin A1c values between the two groups. The trial is now in its fifth year, with completion expected in December 2007. The planned glucose separation has been achieved and maintained to this point. Blood pressure and hemoglobin A1c levels have been reduced from baseline values, and established CV risk factors are within recommended ranges. CONCLUSION: The current results of the VADT show that excellent control of glucose and CV risk factors can be achieved and maintained in the population studied. The results of these interventions on CV outcomes will ultimately have important implications for the clinical care of older patients with advanced type 2 diabetes.

Racial and ethnic disparities in the control of cardiovascular disease risk factors in Southwest American veterans with type 2 diabetes: the Diabetes Outcomes in Veterans Study.

BACKGROUND: Racial/ethnic disparities in cardiovascular disease complications have been observed in diabetic patients. We examined the association between race/ethnicity and cardiovascular disease risk factor control in a large cohort of insulin-treated veterans with type 2 diabetes. METHODS: We conducted a cross-sectional observational study at 3 Veterans Affairs Medical Centers in the American Southwest. Using electronic pharmacy databases, we randomly selected 338 veterans with insulin-treated type 2 diabetes. We collected medical record and patient survey data on diabetes control and management, cardiovascular disease risk factors, comorbidity, demographics, socioeconomic factors, psychological status, and health behaviors. We used analysis of variance and multivariate linear regression to determine the effect of race/ethnicity on glycemic control, insulin treatment intensity, lipid levels, and blood pressure control. RESULTS: The study cohort was comprised of 72 (21.3%) Hispanic subjects (H), 35 (10.4%) African Americans (AA), and 226 (67%) non-Hispanic whites (NHW). The mean (SD) hemoglobin A1c differed significantly by race/ethnicity: NHW 7.86 (1.4)%, H 8.16 (1.6)%, AA 8.84 (2.9)%, p = 0.05. The multivariate-adjusted A1c was significantly higher for AA (+0.93%, p = 0.002) compared to NHW. Insulin doses (unit/day) also differed significantly: NHW 70.6 (48.8), H 58.4 (32.6), and AA 53.1 (36.2), p < 0.01. Multivariate-adjusted insulin doses were significantly lower for AA (-17.8 units/day, p = 0.01) and H (-10.5 units/day, p = 0.04) compared to NHW. Decrements in insulin doses were even greater among minority patients with poorly controlled diabetes (A1c > or = 8%). The disparities in glycemic control and insulin treatment intensity could not be explained by differences in age, body mass index, oral hypoglycemic medications, socioeconomic barriers, attitudes about diabetes care, diabetes knowledge, depression, cognitive dysfunction, or social support. We found no significant racial/ethnic differences in lipid or blood pressure control. CONCLUSION: In our cohort, insulin-treated minority veterans, particularly AA, had poorer glycemic control and received lower doses of insulin than NHW. However, we found no differences for control of other cardiovascular disease risk factors. The diabetes treatment disparity could be due to provider behaviors and/or patient behaviors or preferences. Further research with larger sample sizes and more geographically diverse populations are needed to confirm our findings.

An insulin-degrading enzyme inhibitor decreases amylin degradation, increases amylin-induced cytotoxicity, and increases amyloid formation in insulinoma cell cultures.

Amylin (islet amyloid polypeptide) is the chief component of the islet amyloid found in type 2 diabetes, and amylin fibril precursors may be cytotoxic to pancreatic beta-cells. Little is known about the prevention of amylin aggregation. We investigated the role of insulin-degrading enzyme (IDE) in amylin degradation, amyloid deposition, and cytotoxicity in RIN-m5F insulinoma cells. Human (125)I-labeled amylin degradation was inhibited by 46 and 65% with the addition of 100 nmol/l human amylin or insulin, respectively. (125)I-labeled insulin degradation was inhibited with 100 nmol/l human amylin, rat amylin, and insulin (by 50, 50, and 73%, respectively). The IDE inhibitor bacitracin inhibited amylin degradation by 78% and insulin degradation by 100%. Amyloid staining by Congo red fluorescence was detectable at 100 nmol/l amylin and was pronounced at 1,000 nmol/l amylin treatment for 48 h. Bacitracin treatment markedly increased staining at all amylin concentrations. Bacitracin with amylin caused a dramatic decrease in cell viability compared with amylin alone (68 and 25%, respectively, at 10 nmol/l amylin). In summary, RIN-m5F cells degraded both amylin and insulin through a common proteolytic pathway. IDE inhibition by bacitracin impaired amylin degradation, increased amyloid formation, and increased amylin-induced cytotoxicity, suggesting a role for IDE in amylin clearance and the prevention of amylin aggregation.

Hypoglycemia in stable, insulin-treated veterans with type 2 diabetes: a prospective study of 1662 episodes.

UNLABELLED: We evaluated the incidence, severity, and predisposing risk factors for hypoglycemic episodes in subjects with type 2 diabetes. METHODS: We conducted a prospective observational study of Southwest veterans with stable, insulin-treated type 2 diabetes who were randomly selected from pharmacy databases. Electronically recorded self-monitored blood glucose (SMBG) results were collected during 12 months of routine monitoring. We defined hypoglycemia as an SMBG reading < or =60 mg/dl. Subjects graded the severity of each hypoglycemic episode: 0=asymptomatic, 1=mild/moderate symptoms, 2=severe, with mental impairment or need for assistance. Subjects also reported any predisposing factors for each hypoglycemic episode. RESULTS: We enrolled 344 subjects, mean (S.D.) age of 65.5 (9.7) years, 96.5% were men, and 35.2% were minorities. During an average follow-up of 41.2 (8.6) weeks, 176 subjects (51.2%) documented at least one hypoglycemic reading for a total of 1662 episodes. These subjects had a median of six (interquartile range 2-14.9) hypoglycemic episodes. The mean hypoglycemic blood glucose reading was 49.7 (7.5) mg/dl and the mean symptom score was 0.84 (0.45). Nearly 80% of episodes were symptomatic, 3.4% were severe. Subjects identified a cause for 45.2% of episodes: 53.3% of these were attributed to missing a meal, 23.8% to exercise, and 1.6% followed a medication increase. CONCLUSIONS: A high proportion of stable, insulin-treated subjects developed hypoglycemic episodes, but severe hypoglycemia occurred infrequently. Medication increases were rarely identified as causing hypoglycemic episodes. Efforts to achieve tight glycemic control should recognize that patient behaviors commonly cause hypoglycemia.

A probabilistic model for predicting hypoglycemia in type 2 diabetes mellitus: The Diabetes Outcomes in Veterans Study (DOVES).

BACKGROUND: To develop and validate a method for estimating hypoglycemia risk in stable, insulin-treated subjects with type 2 diabetes mellitus. METHODS: Subjects (n = 195) monitored their blood glucose levels 4 times daily for 8 weeks. An 8-week mean blood glucose value (GLUMEAN) with standard deviation (GLUSD) was derived for each patient. Subjects were then randomly allocated to a derivation or validation set. For the derivation set, we developed a logistic function based on GLUMEAN and GLUSD to describe the 8-week risk of hypoglycemia (blood glucose < or =60 mg/dL [3.3 mmol/L]). This function was used to assign a predicted probability of hypoglycemia to each subject in the validation set. Subjects were assigned to risk quartiles and followed up for up to 52 weeks. RESULTS: We evaluated 195 subjects, 95% of whom were men and 69% of whom were non-Hispanic white. For 72 derivation subjects, GLUMEAN and GLUSD were highly influential determinants of hypoglycemia during intensified monitoring. The 123 validation subjects were followed up for 39.7 +/- 7.1 weeks (mean +/- SD). The occurrence of long-term hypoglycemia differed significantly across risk quartiles (19.4%, 36.7%, 61.3%, and 77.4%, respectively; P<.001). Receiver operating characteristic curve analysis showed that the area for the probability function (0.746 +/- 0.046) was significantly higher than the area for hemoglobin A1c (0.549 +/- 0.052) because their 95% confidence intervals did not overlap. The function also identified subjects who developed long-term hypoglycemia at a rate exceeding the median frequency. CONCLUSIONS: Self-monitoring of blood glucose is superior to hemoglobin A1c measurement in predicting long-term hypoglycemia in persons with type 2 diabetes. The risk of hypoglycemia associated with treatment intensification may be offset by strategies that reduce glucose variability.

Reliability and validity of the DCP among hispanic veterans.

The Diabetes Care Profile (DCP) was designed to measure psychosocial factors related to diabetes and its treatment. This study sought to determine the reliability and validity of the DCP in Hispanic veterans with Type 2 diabetes. Hispanic (n=81) and non-Hispanic White (n=238) patients were recruited at three southwestern VA hospitals. Scale reliabilities calculated by Cronbach's coefficient alpha revealed reliabilities ranging from .54 to .97 in Hispanics and .63 to .95 in non-Hispanic Whites. Only one scale, Monitoring Barriers, differed significantly between the two patient groups. Mean values on the DCP scales were consistent within and across ethnicities lending support for construct validity of the DCP in Hispanics. Convergent validity was also supported for DCP scales within the Hispanic patients as evidenced by correlations in expected directions with external measures.

Intensified blood glucose monitoring improves glycemic control in stable, insulin-treated veterans with type 2 diabetes: the Diabetes Outcomes in Veterans Study (DOVES).

OBJECTIVE: To examine the effect of intensified self-monitored blood glucose (SMBG) testing on glycemic control. RESEARCH DESIGN AND METHODS: Subjects with stable, insulin-treated type 2 diabetes performed SMBG using an electronic blood glucose meter before all meals and at bedtime for 8 weeks. Baseline data were collected on demographics, clinical characteristics, diet, and exercise. HbA(1c) was measured at baseline, at 4 weeks, and at 8 weeks. After the intensified monitoring period, subjects resumed their usual monitoring. HbA(1c) was then measured at 24, 37, and 52 weeks. Multivariate linear regression was used to determine the effect of monitoring on glycemic control. RESULTS: A total of 201 subjects completed the monitoring period. The baseline HbA(1c) (8.10 +/- 1.67%) decreased during the monitoring period by 0.30 +/- 0.68% (P < 0.001) at 4 weeks and by 0.36 +/- 0.88% (P < 0.001) at 8 weeks. Although entry HbA(1c) and compliance independently predicted the week 8 HbA(1c) (r = 0.862, P < 0.001), standardized regression analysis found that compliance with the SMBG protocol influenced the week 8 HbA(1c) more than age, sex, BMI, exercise level, carbohydrate consumption, or treatment intensity at baseline. However, SMBG benefited only subjects whose testing compliance exceeded 75% or with an entry HbA(1c) >8.0%. Decreases in HbA(1c) (-0.31 +/- 1.17%, P = 0.001) persisted in the 159 subjects followed for 52 weeks. CONCLUSIONS: Intensified blood glucose monitoring improved glycemic control in a large cohort of stable, insulin-treated veterans with type 2 diabetes. SMBG provided a strong stimulus for improved self-care resulting in clinically important and sustained reductions in HbA(1c).

Evaluating once- and twice-daily self-monitored blood glucose testing strategies for stable insulin-treated patients with type 2 diabetes : the diabetes outcomes in veterans study.

OBJECTIVE: To evaluate once- and twice-daily self-monitored blood glucose testing strategies in assessing glycemic control and detecting hypoglycemia or hyperglycemia in patients with stable insulin-treated type 2 diabetes. RESEARCH DESIGN AND METHODS: Subjects with stable insulin-treated type 2 diabetes monitored blood glucose four times daily (prebreakfast, prelunch, predinner, and bedtime) for 8 weeks. We correlated mean blood glucose values with HbA(1c) measured after 8 weeks and determined the number of hypoglycemic (< or =3.33 mmol/l) and hyperglycemic (> or =22.20 mmol/l) readings captured at the various testing times. RESULTS: A total of 150 subjects completed the monitoring period; their average age was 67 years, 90% were men, and the mean HbA(1c) at baseline was 8.0 +/- 1.8%. The overall correlation of glucose testing and HbA(1c) was 0.79 (P < 0.0001). Mean blood glucose values for each of the four once-daily testing strategies were significantly correlated with HbA(1c) (r = 0.65-0.70, P < 0.0001), as were mean blood glucose values for each of the six twice-daily testing strategies (r = 0.73-0.75, P < 0.0001). The prebreakfast/prelunch measurements captured the largest proportion (63.6%) of the hypoglycemic readings, the predinner/bedtime measurements captured the largest proportion (66.2%) of hyperglycemic readings, and the prelunch/predinner measurements captured the largest proportion (57.7%) of all out-of-range readings. CONCLUSIONS: Twice-daily testing strategies, particularly prelunch/predinner, effectively assess glycemic control and capture a substantial proportion of out-of-range readings. However, personal testing strategies will vary depending on an individual's risk for hypoglycemia and hyperglycemia.

Insulin-degrading activity in wound fluid.

Patients with diabetes are at great risk of developing lower extremity ulcers. The management of diabetic foot ulcers typically includes early recognition and appropriate clinical care. Recent advances in wound treatment include topical growth factor therapy, which has been successful in diabetic wounds. Growth factors are decreased in wound fluid; this may be due to decreased supply, increased binding, or increased degradation of the naturally occurring growth factors. This study investigates the activity of the insulin-degrading enzyme in wound fluid. Wound fluid was obtained from patients with (n = 17) and without (n = 4) diabetes. Insulin degradation was assayed by incubating [(125)I]insulin with wound fluid and precipitation in trichloroacetic acid. Fluid from nondiabetics degraded 2.22 +/- 0.73%, whereas diabetic fluid degraded significantly more (6.13 +/- 1.48%; P < 0.05). In patients with diabetes, the degradation of insulin by wound fluid correlated with glucose control (hemoglobin A(1c); r(2) = 0.5353; P < 0.001), and patients with worse outcomes (i.e. amputation) had higher wound fluid insulin degradation. The biochemical characteristics of insulin degradation in the wound fluid were consistent with the characteristics of insulin-degrading enzyme. These data suggest that glucose control is a critical factor in wound healing, but a reduction in the insulin-degrading activity in the wound fluid is also a potential therapeutic target.

Reduced action of insulin glargine on protein and lipid metabolism: possible relationship to cellular hormone metabolism.

Insulin analogues are used in the treatment of diabetes to mimic physiological insulin secretion. Glargine is used to provide basal insulin levels. Previous work has shown no differences in glucose uptake when glargine was compared to native insulin. The action of insulin on protein and lipid metabolism is studied infrequently, but these important actions should be considered with insulin analogues. In HepG2 cells, protein degradation was inhibited significantly less by glargine (15% over 3 hours) than by insulin (approximately 20% over 3 hours) (P < .05). Lipid metabolism was investigated in 3T3-L1 cells. In these cells glucose oxidation to CO2 was effected equally, but glargine was less potent than insulin at inhibiting epinephrine-stimulated lipolysis (EC50 = 1.4 v 0.35 nmol/L, P < .001) and at stimulating lipogenesis (EC50 = 1.27 v 8.06 nmol/L, P < .01). Since the action of insulin on protein and lipid metabolism has been suggested to be due to the metabolism of the hormone, we compared the cellular handling of 125I[A14]-glargine to 125I[A14]-insulin in HepG2 cells. While binding of glargine to the insulin receptor was identical to insulin, degradation of glargine was reduced compared to insulin (16.3% +/- 0.3% v 21.6% +/- 0.4% degraded/h, P < .01). Less degraded glargine than insulin was released from cells previously loaded with radiolabeled material (50.1% +/- 2.4% v 58.3% +/- 1.4%/2 h, P < .02). The amount of intact glargine released was concomitantly increased compared to insulin (44.8% +/- 2.6% v 35.8% +/- 1.4%/2 h, P < .02). These data provide further evidence for a relationship between insulin metabolism and insulin action on protein and lipid metabolism; however, the clinical relevance of these differences is hard to realize, since for the most part glargine, used as a basal insulin, is administered in addition to other shorter-acting insulin or analogues, and their effects will mask or reduce glargine effects on lipolysis and protein degradation. However, these studies do show that properties of insulin other than glucose metabolism and mitogenesis must be considered when studying insulin analogues.

Inhibition of proteasome activity by selected amino acids.

Cellular protein homeostasis is a balance between synthesis and degradation. Protein degradation is regulated by hormones (eg, insulin) and nutrients (eg, amino acids). Certain amino acids are capable of decreasing cellular protein degradation, with evidence that this is mediated through altered lysosomal function. However, proteasomes, the major cytosolic protein degrading machinery, are being shown to play a central role in the control of protein turnover in the cell. In this study we show that the amino acids, isoleucine, leucine, tyrosine, phenylalanine, tryptophan, lysine, and arginine are capable of inhibiting the chymotrypsin-like activity of the proteasome in a dose-dependent manner. Leucine, tyrosine, and phenylalanine have a substantial effect at normal serum concentrations. The effect was greater in a proteasome preparation derived from muscle compared to a similar preparation from liver. On the assumption that amino acid-induced alterations in cellular protein degradation reflect the inhibitory changes in proteasomal activity shown here, we may conclude that amino acid control of cellular protein degradation is mediated, at least in part, through proteasomes.

Factors affecting hypoglycemia awareness in insulin-treated type 2 diabetes: The Diabetes Outcomes in Veterans Study (DOVES).

OBJECTIVE: To identify clinical factors that affect hypoglycemia perception in type 2 diabetes. METHODS: Prospective observational study of 344 insulin-treated subjects randomly selected from pharmacy records at three large medical centers. At entry, subjects underwent an extensive psychological evaluation and then monitored their blood glucoses in their usual fashion for up to 52 weeks using a glucose meter capable of storing 1000 readings. For blood glucoses