Short-term effectiveness of dapagliflozin versus DPP-4 inhibitors in elderly patients with type 2 diabetes: a multicentre retrospective study.

AIM: To compare effectiveness of dapagliflozin versus DPP-4 inhibitors on individualized HbA1c targets and extra-glycaemic endpoints among elderly patients with type 2 diabetes (T2D). METHODS: This was a multicentre retrospective study on patients aged 70-80 years with HbA1c above individualized target and starting dapagliflozin or DPP-4 inhibitors in 2015-2017. The primary outcome was the proportion reaching individualized HbA1c targets. Confounding by indication was addressed by inverse probability of treatment weighting (IPTW), multivariable adjustment (MVA), or propensity score matching (PSM). RESULTS: Patients initiating dapagliflozin (n = 445) differed from those initiating DPP-4i (n = 977) and balance between groups was achieved with IPTW or PSM. The median follow-up was 7.5 months and baseline HbA1c was 8.3%. A smaller proportion of patients initiating dapagliflozin attained individualized HbA1c target as compared to those initiating DPP-4 inhibitors (RR 0.73, p < 0.0001). IPTW, MVA, and PSM yielded similar results. Between-group difference in the primary outcome was observed among patients with lower eGFR or longer disease duration. Dapagliflozin allowed greater reductions in body weight and blood pressure than DPP-4 inhibitors. CONCLUSIONS: Elderly patients with T2D initiating dapagliflozin had a lower probability of achieving individualized HbA1c targets than those initiating DPP-4 inhibitors but displayed better improvements in extra-glycaemic endpoints.

LEADER 5: prevalence and cardiometabolic impact of obesity in cardiovascular high-risk patients with type 2 diabetes mellitus: baseline global data from the LEADER trial.

BACKGROUND: Epidemiological data on obesity are needed, particularly in patients with type 2 diabetes mellitus (T2DM) and high cardiovascular (CV) risk. We used the baseline data of liraglutide effect and action in diabetes: evaluation of CV outcome results-A long term Evaluation (LEADER) (a clinical trial to assess the CV safety of liraglutide) to investigate: (i) prevalence of overweight and obesity; (ii) relationship of the major cardiometabolic risk factors with anthropometric measures of adiposity [body mass index (BMI) and waist circumference (WC)]; and (iii) cardiometabolic treatment intensity in relation to BMI and WC. METHODS: LEADER enrolled two distinct populations of high-risk patients with T2DM in 32 countries: (1) aged ≥50 years with prior CV disease; (2) aged ≥60 years with one or more CV risk factors. Associations of metabolic variables, demographic variables and treatment intensity with anthropometric measurements (BMI and WC) were explored using regression models (ClinicalTrials.gov identifier: NCT01179048). RESULTS: Mean BMI was 32.5 ± 6.3 kg/m(2) and only 9.1 % had BMI <25 kg/m(2). The prevalence of healthy WC was also extremely low (6.4 % according to International Joint Interim Statement for the Harmonization of the Metabolic Syndrome criteria). Obesity was associated with being younger, female, previous smoker, Caucasian, American, with shorter diabetes duration, uncontrolled blood pressure (BP), antihypertensive agents, insulin plus oral antihyperglycaemic treatment, higher levels of triglycerides and lower levels of high-density lipoprotein cholesterol. CONCLUSIONS: Overweight and obesity are prevalent in high CV risk patients with T2DM. BMI and WC are related to the major cardiometabolic risk factors. Furthermore, treatment intensity, such as insulin, statins or oral antihypertensive drugs, is higher in those who are overweight or obese; while BP and lipid control in these patients are remarkably suboptimal. LEADER confers a unique opportunity to explore the longitudinal effect of weight on CV risk factors and hard endpoints.

Achieving the composite endpoint of glycated haemoglobin <7.0%, no weight gain and no hypoglycaemia in the once-weekly dulaglutide AWARD programme.

AIM: To compare the effectiveness of dulaglutide 1.5 and 0.75 mg with active comparators and placebo with regard to a composite endpoint of glycated haemoglobin (HbA1c), weight and hypoglycaemia, using post hoc analyses. METHODS: A logistic regression analysis was performed on the intention-to-treat population, using data from the last observation carried forward, and the composite endpoint of HbA1c <7.0% (53 mmol/mol), no weight gain (≤0 kg) and no hypoglycaemia (glucose <3.0 mmol/l or severe hypoglycaemia) after 26 weeks for each trial in the AWARD programme separately. RESULTS: At 26 weeks, within each study, 37-58% of patients on dulaglutide 1.5 mg, 27-49% of patients on dulaglutide 0.75 mg, and 9-61% of patients on active comparators achieved the composite endpoint. Significantly more patients reached the composite endpoint with dulaglutide 1.5 mg than with metformin, sitagliptin, exenatide twice daily or insulin glargine: odds ratio (OR) 1.5 [95% confidence interval (CI) 1.0, 2.2; p < 0.05], OR 4.5 (95% CI 3.0, 6.6; p < 0.001), OR 2.6 (95% CI 1.8, 3.7; p < 0.001) and OR 7.4 (95% CI 4.4, 12.6; p < 0.001), respectively, with no difference between dulaglutide 1.5 mg and liraglutide 1.8 mg. In addition, significantly more patients reached the composite endpoint with dulaglutide 0.75 mg than with sitagliptin or insulin glargine: OR 3.3 (95% CI 2.2, 4.8; p < 0.001) and OR 4.5 (95% CI 2.7, 7.8; p < 0.001), respectively. CONCLUSIONS: Dulaglutide is an effective treatment option, resulting in a similar or greater proportion of patients reaching the HbA1c target of <7.0% (53 mmol/mol), without weight gain or hypoglycaemia compared with active comparators.

Frequency of cancer events with saxagliptin in the SAVOR-TIMI 53 trial.

The Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus (SAVOR)-Thrombolysis in Myocardial Infarction (TIMI) 53 trial randomized trial of 16,492 patients (placebo, n = 8212; saxagliptin, n = 8280) treated and followed for a median of 2.1 years afforded an opportunity to explore whether there was any association with cancer reported as a serious adverse event. At least one cancer event was reported by 688 patients (4.1%): 362 (4.3%) and 326 (3.8%) in the placebo and saxagliptin arms, respectively (p = 0.13). There were 59 (0.6%) deaths adjudicated as malignancy deaths with placebo and 53 (0.6%) with saxagliptin. Stratification by gender, age, race and ethnicity, diabetes duration, baseline glycated haemoglobin and pharmacotherapy did not show any clinically meaningful differences between the two study arms. The overall number of cancer events and malignancy-associated mortality rates were generally balanced between the placebo and saxagliptin groups, suggesting a null relationship with saxagliptin use over the median follow-up of 2.1 years. Multivariable modelling showed that male gender, dyslipidaemia and current smoking were independent predictors of cancer. These randomized data with adequate numbers of cancer cases are reassuring but limited, by the short follow-up in a trial not designed to test this hypothesis.

Impact of treatment with saxagliptin on glycaemic stability and ß-cell function in the SAVOR-TIMI 53 study.

AIMS: To study the effects of saxagliptin, a dipeptidyl peptidase-4 inhibitor, on glycaemic stability and ß-cell function in the SAVOR-TIMI 53 trial. METHODS: We randomized 16,492 patients with type 2 diabetes (T2D) to saxagliptin or placebo, added to current antidiabetic medications, and followed them for a median of 2.1 years. Glycaemic instability was defined by: (i) a glycated haemoglobin (HbA1c) increase of ≥ 0.5% post-randomization; (ii) the initiation of new antidiabetic medications for ≥ 3 months; or (iii) an increase in dose of oral antidiabetic medication or ≥ 25% increase in insulin dose for ≥ 3 months. ß-cell function was assessed according to fasting homeostatic model 2 assessment of ß-cell function (HOMA-2ß) values at baseline and at year 2 in patients not treated with insulin. RESULTS: Compared with placebo, participants treated with saxagliptin had a reduction in the development of glycaemic instability (hazard ratio 0.71; 95% confidence interval 0.68-0.74; p < 0.0001). In participants treated with saxagliptin compared with placebo, the occurrence of an HbA1c increase of ≥ 0.5% was reduced by 35.2%; initiation of insulin was decreased by 31.7% and the increases in doses of an oral antidiabetic drug or insulin were reduced by 19.5 and 23.5%, respectively (all p < 0.0001). At 2 years, HOMA-2ß values decreased by 4.9% in participants treated with placebo, compared with an increase of 1.1% in those treated with saxagliptin (p < 0.0001). CONCLUSIONS: Saxagliptin improved glycaemia and prevented the reduction in HOMA-2ß values. Saxagliptin may reduce the usual decline in ß-cell function in T2D, thereby slowing diabetes progression.

Baseline characteristics of the patient population in the Saxagliptin Assessment of Vascular Outcomes Recorded in patients with diabetes mellitus (SAVOR)-TIMI 53 trial.

BACKGROUND AND AIMS: SAVOR-TIMI 53 was designed to study the effects of the DPP-4 inhibitor saxagliptin on cardiovascular outcomes in high risk type 2 diabetes patients with diverse levels of diabetes control and background anti-diabetic drugs. The goal of this article is to describe the baseline characteristics of this hypothesis driven study. MATERIALS AND METHODS: A total of 16 496 diabetic patients from North America (31.9%), Western Europe (26.0%), Eastern Europe (17.3%), Latin America (16.4%) and Asia (8.3%), with either established cardiovascular disease (78.3%) or with ≥two additional cardiovascular risk factors (21.7%) were randomised to saxagliptin or placebo. Biomarkers of inflammation and insulin resistance were taken at baseline and 2 years later in order to correlate saxagliptin effect on cardiovascular outcome to its effect on inflammation and insulin resistance. RESULTS: Mean [+/-standard deviation (SD)] age was 65.0 (+/-8.6) years, 66.9% were male, body mass index was 31.2 kg/m² (+/-5.6), mean diabetes duration was 11.9 years (+/-8.9) and the mean HbA1c 8.0% (+/-1.4%). HbA1c < 7% was most prevalent among North Americans (30.8%) and least among Asians (15.1%), whereas HbA1c > 9% was 30.7% in Latin America 27.0% in Asia and 15.1% in North America. Diabetic retinopathy was reported in 12.3% of patients, nephropathy in 17.7% and amputation in 2.5%. Diabetic treatments categories were as follows: no medication (5.4%), 1 oral anti-diabetic drug (OAD) (25.0%), ≥2 OAD (27.7%) and/or insulin (40.9%). The prevalence of micro-albuminuria was twice as high among insulin users compared with users of ≥2 OAD. Baseline statin use (78.3% overall) varied by region. CONCLUSION: The SAVOR-TIMI 53 patient population, with differing background diabetes control and anti-diabetic treatment, provides global representation of diabetic patients with established cardiovascular disease or at high risk for cardiovascular disease and is well-positioned to determine the effect of saxagliptin on cardiovascular events.

Basal state hyperinsulinemia in healthy normoglycemic adults heralds dysglycemia after more than two decades of follow up.

BACKGROUND: In a preliminary report, we found an association between hyperinsulinemia in the basal (fasting) state and the development of diabetes. OBJECTIVES: The current analysis further explored the long term link between basal hyperinsulinemia and conversion to dysglycemia. METHODS: This is a prospective study with up to 24 years of follow-up of 515 normoglycemic individuals (mean age at follow up = 70.3 ± 7.0; range 58-94) of an Israeli cohort. Fasting glucose and insulin were measured, and dysglycemia was defined as fasting glucose > 100 mg/dL. RESULTS: At the end of the follow-up period, almost half had progressed to dysglycemia. Male sex and elevated baseline levels of basal insulin, body mass index, blood glucose and blood pressure each favoured progression to dysglycemia over the subsequent two decades. A multivariate logistic regression model identified basal hyperinsulinemia as the strongest predictor for progression to dysglycemia (odds ratio = 1.79; 95% confidence interval 1.12-2.88), while controlling for ethnicity, blood pressure, fasting glucose, male sex, body mass index and age. CONCLUSIONS: Basal hyperinsulinemia in normoglycemic adults constitutes an independent risk factor for metabolic deterioration to dysglycemia over adulthood, and may help to identify apparently healthy subjects at increased risk for diabetes.

Benefits of a simple glycaemic protocol in an orthopaedic surgery ward: a randomized prospective study.

BACKGROUND: Hyperglycaemia and diabetes mellitus are common in patients hospitalized in the orthopaedic surgery ward. However, glycaemic control obtained during hospitalization is often suboptimal. No method for achieving adequate glycaemic control in this population has been validated in an in-hospital setting. INTERVENTION: An intervention including an intensive subcutaneous insulin protocol in the orthopaedic department. METHODS: All diabetic patients admitted to the Department of Orthopaedic Surgery were prospectively randomized during a 6-month period. One group (n = 30) received standard care with sliding scale insulin and the other group (n = 35) received the intervention protocol. During the intervention period, the staff was briefed on the importance of glucose monitoring and control. An intensive multiple-injection protocol consisting of four daily regular/neutral protamine hagedorn (NPH) insulin injections was initiated in diabetic patients. The programme was followed up by a consulting diabetologist. RESULTS: Mean blood glucose levels throughout the hospitalization were 161.48 ± 3.8 mg/dL in the intervention group versus 175.29 ± 2.3 mg/dL in the control group (p < 0.0005). Hospitalization was shorter by 2 days in the intervention group (p < 0.05). The number of severe hyperglycaemic events (blood glucose level above 400 mg%) was significantly lower (p < 0.05) in the intervention group. There was no significant difference in the number of hypoglycaemic events. CONCLUSIONS: The suggested four-step intervention regimen improved glycaemic control of hospitalized patients in the orthopaedic department and simplified the 'in-house' treatment of the diabetic patient. Hospital stays were reduced on average by two days (p < 0.05).

Practical guidance on intensification of insulin therapy with BIAsp 30: a consensus statement.

BACKGROUND: Basal insulin and premix insulin are commonly prescribed first-line insulin therapies for patients failing to maintain glycaemic control on oral therapy. When control on these insulins starts to drift, premix analogues, such as biphasic insulin aspart 30/70 (BIAsp 30), are a simple and effective tool for intensification as they can be injected up to three-times daily (TID). However, at present, international recommendations for intensification of insulin therapy using premix analogues are limited and specific guidance on dosing is not available for many scenarios. METHODS: In October 2008, an international expert panel met to review the current guidelines for insulin intensification with BIAsp 30 in patients with type 2 diabetes, with the aim of developing practical guidance for general and specialist practitioners. RESULTS: Simple treatment algorithms have been developed for (i) patients on basal insulin (human or analogue) once daily or twice daily (BID) who need intensification to BIAsp 30 BID, and (ii) patients on BIAsp 30 once daily or BID who can be intensified to BIAsp 30 BID or TID. As well as these algorithms, specific guidance has been provided on dose transfer (from basal insulin to BIAsp 30), dose split (when intensifying from once daily to BID), and combination oral therapies. In addition, a guide to dose titration is included. CONCLUSIONS: The guidelines presented here should enable general or specialist practitioners to use BIAsp 30 to intensify the insulin therapy of patients failing on basal insulin or BIAsp 30 once or twice daily.

Effects of early breastfeeding on neonatal glucose levels of term infants born to women with gestational diabetes.

BACKGROUND: Infants born to diabetic women are at higher risk for hypoglycaemia related to hyperinsulinism in response to maternal hyperglycaemia during pregnancy. As such, recommendations to prevent neonatal hypoglycaemia include infant feeding in the early postpartum period. The present study aimed to examine the effect of early breastfeeding and type of nutrition used for the first feed (human milk or formula) on glucose levels in infants born to women with gestational diabetes. METHODS: The prospective pilot study of 84 infants born to gestational diabetic women examined the glycaemic levels of infants who were breastfed in the delivery room compared to glycaemic levels of those who were not. The study also compared the glycaemic levels of infants who breastfed with those who received formula for their first feed. RESULTS: Infants who were breastfed in the delivery room had a significantly lower rate of borderline hypoglycaemia than those who were not breastfed in the early postpartum period (10% versus 28%; Fisher's exact test., P = 0.05,). Likewise, infants breastfed in the delivery room had significantly higher mean blood glucose level compared to infants who were not breastfed in the delivery room (3.17 versus 2.86 mmol L(-1), P = 0.03). Additionally, breastfed infants had a significantly higher mean blood glucose level compared to those who were formula fed for their first feed (3.20 versus 2.68 mmol L(-1), P = 0.002). CONCLUSIONS: Early breastfeeding may facilitate glycaemic stability in infants born to women with gestational diabetes.

Diabetes and radiocontrast media increase endothelin converting enzyme-1 in the kidney.

Plasma endothelin-1 levels rise in diabetes and after exposure to contrast media suggesting a role in progressive diabetic and acute radiocontrast nephropathies. Here we studied individual and combined effects of streptozotocin-induced diabetes and contrast media on renal endothelin converting enzyme-1 levels in the rat. In vivo, medullary (but not cortical) endothelin converting enzyme protein gradually increased 4 to 5-fold following the induction of diabetes or after the administration of contrast media but rose 15-fold when diabetic rats were given contrast media. Changes in mRNA expression paralleled those of the protein. Immunohistochemistry confirmed that increased tubular and endothelial cell endothelin converting enzyme-1 were most pronounced in the medulla. In vitro, endothelin-1 levels increased 3-fold following incubation of endothelial cells with media high in glucose or with contrast and 4-fold with their combination. Endothelin converting enzyme-1 protein and mRNA expression changed in a similar pattern while prepro endothelin-1 mRNA increased with each insult but not in an additive way. Our study shows that diabetes and contrast media up-regulate renal medullary endothelin converting enzyme-1 expression and synthesis.

Activation of skeletal muscle casein kinase II by insulin is not diminished in subjects with insulin resistance.

Insulin resistance, which may precede the development of non-insulin-dependent diabetes mellitus in Pima Indians, appears to result from a postreceptor defect in signal transduction in skeletal muscle. To identify the putative postreceptor lesion responsible for insulin resistance in Pima Indians, we investigated the influence of insulin on the activity of casein kinase II (CKII) in skeletal muscle of seven insulin-sensitive, four insulin-resistant, nondiabetic, and five insulin-resistant diabetic Pima Indians during a 2 h hyperinsulinemic, euglycemic clamp. In sensitive subjects, CKII was transiently activated reaching a maximum over basal activity (42%) at 45 min before declining. CKII was also stimulated in resistant (19%) and diabetic (34%) subjects. Basal CKII activity in resistant subjects was 40% higher than in either sensitive or diabetic subjects, although the concentration of CKII protein, as determined by Western blotting, was equal among the three groups. Basal CKII activity was correlated with fasting plasma insulin concentrations, suggesting that the higher activity in resistant subjects resulted from insulin action. Extracts of muscle obtained from all three groups either before or after insulin administration were treated with immobilized alkaline phosphatase, which reduced and equalized CKII activity. These results suggest that insulin stimulates CKII activity in human skeletal muscle by a mechanism involving phosphorylation of either CKII or of an effector molecule, and support the idea that elevated basal activity in resistant subjects results from insulin action. It appears that the ability of insulin to activate CKII in skeletal muscle is not impaired in insulin-resistant Pima Indians, and that the biochemical lesion responsible for insulin resistance occurs either downstream from CKII or in a different pathway of insulin action.

Abnormal regulation of ribosomal protein S6 kinase by insulin in skeletal muscle of insulin-resistant humans.

Insulin resistance in Pima Indians appears to result from a post-receptor impairment of insulin signal transduction that affects only some responses to insulin. To identify the primary lesion responsible for insulin resistance, we investigated the influence of insulin on ribosomal protein S6 kinase activities in skeletal muscle of insulin-sensitive and insulin-resistant nondiabetic Pima Indians during a 2-h hyperinsulinemic, euglycemic clamp. In sensitive subjects, S6 kinase activity was transiently activated fivefold over basal activity by 45 min of insulin infusion. Although basal activities in the two groups were similar, the response to insulin was delayed and restricted to about threefold over basal in subjects resistant to insulin. Two major S6 kinase activities in extracts of human muscle were resolved by chromatography on Mono Q. Peak 1, which accounted for basal activity owes to an enzyme antigenically related to the 90-kD S6 kinase II, a member of the rsk gene family. The major insulin-stimulated S6 kinase eluted as peak 2 and is antigenically related to a 70-kD S6 kinase. Our results show that insulin resistance impairs signaling to the 70-kD S6 kinase.

Defective insulin response of phosphorylase phosphatase in insulin-resistant humans.

Insulin-stimulated glycogen synthase activity in human muscle is reduced in insulin-resistant subjects. Insulin regulation of human muscle glycogen synthase may require activation of a type-1 protein phosphatase (PP-1). We investigated the change of phosphorylase phosphatase and glycogen synthase activities in muscle biopsies obtained during a 2-h hyperinsulinemic euglycemic clamp in 12 insulin-sensitive (group S) and 8 insulin-resistant (group R) subjects. Fasting phosphorylase phosphatase activity was lower in group R than in group S, and did not increase significantly with insulin infusion in group R until 20 min. In group S, phosphorylase phosphatase was significantly stimulated by 10 min, remaining significantly higher than in group R at all time points. The insulin-mediated changes in phosphatase activities were not decreased by 3 nM okadaic acid but were completely inhibited by 1 microM okadaic acid, thereby verifying that insulin-stimulated phosphorylase phosphatase is accounted for by a PP-1. Subcellular fractionation demonstrated reduced fasting PP-1 activities in both the glycogen and cytosolic fractions of muscle obtained from subjects in group R compared to those in group S. These results suggest that insulin activation of PP-1 could contribute to the stimulation of glycogen synthase by this hormone in human muscle. Lower fasting PP-1 activity in cytosol and glycogen fractions plus lower insulin-stimulated PP-1 activity could explain, in part, reduced insulin-stimulated glycogen synthase in skeletal muscle of insulin-resistant subjects.

Insulin resistance associated with lower rates of weight gain in Pima Indians.

UNLABELLED: Insulin resistance is commonly associated with obesity and noninsulin-dependent diabetes. Whereas it predicts the development of diabetes, its effect on body weight change is unknown. We measured glucose disposal rates at submaximally- and maximally-stimulating insulin concentrations in 192 nondiabetic Pima Indians and followed their weight change over 3.5 +/- 1.8 y (mean +/- SD). RESULTS: (a) Insulin-resistant subjects gained less weight than insulin-sensitive subjects (3.1 vs. 7.6 kg, P less than 0.0001). (b) The percent weight change per year correlated with glucose disposal at submaximally-(r = 0.19, P less than 0.01) and maximally-stimulating (r = 0.34, P less than 0.0001) insulin concentrations independent of sex, age, initial weight, and 24-h energy expenditure; the correlations were stronger for glucose oxidation than for glucose storage. (c) Weight gain was associated with an increase in insulin resistance more than four times that predicted from the cross-sectional data. We conclude that insulin resistance is associated with a reduced risk of weight gain in nondiabetic Pima Indians.

Rationale and design of a study to evaluate management of proteinuria in patients at high risk for vascular events: the IMPROVE trial.

Declining kidney function predicts increasing cardiovascular risk in people with hypertension. Microalbuminuria is a marker for cardiovascular risk and declining kidney function. Agents that block the renin-angiotensin-aldosterone system (RAAS), notably angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), reduce proteinuria and microalbuminuria, lower blood pressure and slow the progression of proteinuric kidney disease. Evidence is accumulating that the combination of an ACE inhibitor and an ARB is the optimal means of RAAS blockade in this setting, slowing the progression of nephropathy independently of blood pressure lowering to a greater degree than can be achieved using maximum approved doses of either agent alone. However, the emerging therapeutic potential of ACE inhibitor/ARB combination therapy in hypertensive kidney disease requires further characterization. The Irbesartan in the Management of PROteinuric patients at high risk for Vascular Events trial aims to determine definitively whether the combination therapy of an ARB, irbesartan and an ACE inhibitor, ramipril, is more effective than ramipril alone in reducing the urinary albumin excretion rate in patients at high cardiovascular risk with hypertension and proteinuria or microalbuminuria.

Characterization of the regulatory region of the human testis-specific form of the pyruvate dehydrogenase alpha-subunit (PDHA-2) gene.

The alpha-subunit of human pyruvate dehydrogenase (E(1)) is encoded by two separate genes. The gene located on chromosome X (PDHA-1) is expressed in somatic tissues, whereas the second gene (PDHA-2), located on chromosome 4, is expressed only in post-meiotic spermatogenic cells. A genomic fragment harboring the human gene encoding PDHA-2 has been isolated and approximately 800 nucleotides of the promoter region have been characterized. Functional studies of the promoter indicate the presence of both enhancer and repressor elements that are common to other genes that are only expressed in mature sperm.

Effect of hyperglycemia on pain perception and on efficacy of morphine analgesia in rats.

The effect exerted by different hyperglycemic states on the pain threshold and on the analgesic potential of morphine was studied in male Sabra rats with the hot plate device. Hyperglycemia induced by an intraperitoneal injection of 0.014 mol/kg glucose or an acute or chronic diabetic state induced by streptozocin injection did not significantly alter the pain threshold. However, states of acute and chronic diabetes markedly blunted the analgesic effect of morphine (5 mg/kg). Sabra rats maintained on a cocktail of glucose-saccharin, thought to activate the release of endogenous opioids, demonstrated an increased pain threshold and rapidly developed resistance to the analgesic effect of morphine. Previous studies have shown that glucose in high concentration may interfere with the interaction of morphine on the opiate receptor. The influence of the diabetic state on beta-endorphin synthesis and concentration in the central nervous system is another factor that might change pain perception in diabetes. We propose that in diabetes, generally, the pain threshold is adequately maintained, despite the antagonistic effect of glucose, partly due to a compensatory increased secretion of endogenous opioid peptides. We hypothesize that in patients with chronic painful diabetic neuropathy, these normal analgesic response mechanisms may be overwhelmed either by an excess of nociceptive impulses from diseased peripheral nerves or conceivably by a failure of endogenous opioid secretory response to the hyperglycemia.