Effect of GLP-1 and GIP on C-peptide secretion after glucagon or mixed meal tests: Significance in assessing B-cell function in diabetes.

BACKGROUND: The aim of the study was to investigate the different B-cell responses after a glucagon stimulation test (GST) versus mixed meal tolerance test (MMTT). METHODS: We conducted GST and MMTT in 10 healthy people (aged 25-40 years) and measured C-peptide, gastric inhibitory peptide (GIP) and glucagon-like peptide-1 (GLP-1) at different time points after the administration of 1 mg i.v. glucagon for GST or a liquid mixed meal for MMTT. RESULTS: The GST stimulated C-peptide showed a mean increase of 147.1%, whereas the mean increase of MMTT stimulated C-peptide was 99.82% (Δincrease = 47.2%). Maximum C-peptide level reached with the MMTT was greater than that obtained with the GST (C-pept max MMTT = 2.35 nmol/L vs C-pep max GST = 1.9 nmol/L). A positive and linear correlation was found between the GST incremental area under the curve C-peptide and the MMTT incremental area under the curve C-peptide (r = 0.618, P = .05). After GST, there was no increment of GIP and glucagon like peptide-1 levels compared to baseline levels. A positive and linear correlation between GIP and C-peptide levels was observed only for the MMTT (r = 0.922, P = .008) indicating that in the GST, the C-peptide response is independent of the incretin axis response. CONCLUSIONS: Although the 2 stimulation tests may elicit a similar response in C-peptide secretion, B-cell response to MMTT depends on a functionally normal incretin axis. These results may have implications when investigating the B-cell response in people with diabetes and for studies in which stimulated C-peptide secretion is used as primary or secondary outcome for response to therapy.

A 6-month follow-up study of the randomized controlled Ma-Pi macrobiotic dietary intervention (MADIAB trial) in type 2 diabetes.

BACKGROUND: In the MADIAB trial (a 21-day randomized, controlled trial in patients with type 2 diabetes (T2D)), intervention with the Ma-Pi 2 macrobiotic diet resulted in significantly greater improvements in metabolic control compared with a standard recommended diet for patients with T2D. We report on a 6-month follow-up study, which investigated, whether these benefits extended beyond the 21-day intensive dietary intervention, in real-world conditions. SUBJECTS: At the end of the MADIAB trial (baseline of this follow-up study), all participants continued their assigned diet (Ma-Pi or control) for 6 months. The Ma-Pi 2 group followed the Ma-Pi 4 diet during this follow-up study. Forty of the original 51 subjects (78.4%) participated in the follow-up (body mass index, 27-45 kg m(-2); age, 40-75 years). Primary outcome was percentage change from baseline in HbA1c; secondary outcomes were anthropometric data and lipid panel. RESULTS: A significantly greater median percentage reduction was observed for HbA1c in the Ma-Pi group (-11.27% (95% confidence interval (CI): -10.17; -12.36)) compared with the control group (-5.88% (95% CI: -3.79; -7.98)) (P < 0.001). Total and low-density lipoprotein (LDL) cholesterol increased in both groups with no differences between groups (P=0.331 and P=0.082, respectively). After correcting for age and gender, the Ma-Pi diet was associated with a higher percentage reduction in HbA1c (95% CI: 2.56; 7.61) and body weight (95% CI: 0.40; 3.99), and a higher percentage increase in LDL cholesterol (95% CI: -1.52; -33.16). However, all participants' total and LDL cholesterol levels remained within recommended ranges (<200 mg dl(-1) and <100 mg dl(-1), respectively). The Ma-Pi diet group achieved the target median HbA1c value (<5.7% (39 mmol mol(-1))) at 6 months. CONCLUSIONS: Both the Ma-Pi and control diets maintained their benefits beyond the 21-day intensive monitored intervention over a 6-month follow-up in real-world conditions. The Ma-Pi diet resulted in greater improvement in glycemic control.

Relationship of exercise volume to improvements of quality of life with supervised exercise training in patients with type 2 diabetes in a randomised controlled trial: the Italian Diabetes and Exercise Study (IDES).

AIMS/HYPOTHESIS: A positive impact of exercise intervention programmes on quality of life (QoL) may be important for long-term patient compliance to exercise recommendations. We have previously shown that QoL improves significantly with supervised exercise, whereas it worsens with counselling alone, in patients with type 2 diabetes from the Italian Diabetes and Exercise Study (IDES). Here, we report data on the relationship between changes in QoL and volume of physical activity/exercise in these individuals. METHODS: This multicentre parallel randomised controlled, open-label, trial enrolled sedentary patients with type 2 diabetes (n = 606 of 691 eligible) in 22 outpatient diabetes clinics. Patients were randomised by centre, age and diabetes treatment using a permuted-block design to twice-a-week supervised aerobic and resistance training plus exercise counselling (exercise group) versus counselling alone (control group) for 12 months. Health-related QoL was assessed by the 36-Item Short Form (SF-36) Health Survey. RESULTS: In the exercise group (n = 268 of 303 randomised), there was a trend for increasing QoL with increasing exercise volume, with significant improvement of the physical component summary (PCS) measure only above 17.5 metabolic equivalents h⁻¹ week⁻¹ and a clear volume-relationship for the mental component summary (MCS) measure. A relationship with volume of physical activity also was observed in the control group (n = 260 of 303 randomised), despite overall deterioration of all scores. Independent correlates of improvements in both PCS and MCS were exercise volume, study arm and, inversely, baseline score. CONCLUSIONS/INTERPRETATION: This large trial shows a relationship between changes in physical and mental health-related QoL measures and volume of physical activity/exercise, with supervised exercise training also providing volume-independent benefits.

Anti-inflammatory effect of exercise training in subjects with type 2 diabetes and the metabolic syndrome is dependent on exercise modalities and independent of weight loss.

BACKGROUND AND AIMS: We investigated the effect of different exercise modalities on high sensitivity-C reactive protein (hs-CRP) and other inflammatory markers in patients with type 2 diabetes and the metabolic syndrome. METHODS AND RESULTS: Eighty-two patients were randomized into 4 groups: sedentary control (A); receiving counseling to perform low-intensity physical activity (B); performing prescribed and supervised high-intensity aerobic (C) or aerobic+resistance (D) exercise (with the same caloric expenditure) for 12 months. Evaluation of leisure-time physical activity and assessment of physical fitness, cardiovascular risk factors and inflammatory biomarkers was performed at baseline and every 3 months. Volume of physical activity increased and HbA(1c) decreased in Groups B-D. VO(2max), HOMA-IR index, HDL-cholesterol, waist circumference and albuminuria improved in Groups C and D, whereas strength and flexibility improved only in Group D. Levels of hs-CRP decreased in all three exercising groups, but the reduction was significant only in Groups C and D, and particularly in Group D. Changes in VO(2max) and the exercise modalities were strong predictors of hs-CRP reduction, independent of body weight. Leptin, resistin and interleukin-6 decreased, whereas adiponectin increased in Groups C and D. Interleukin-1ß, tumor necrosis factor-α and interferon-γ decreased, whereas anti-inflammatory interleukin-4 and 10 increased only in Group D. CONCLUSION: Physical exercise in type 2 diabetic patients with the metabolic syndrome is associated with a significant reduction of hs-CRP and other inflammatory and insulin resistance biomarkers, independent of weight loss. Long-term high-intensity (preferably mixed) training, in addition to daytime physical activity, is required to obtain a significant anti-inflammatory effect.

Physical activity/exercise training in type 2 diabetes. The role of the Italian Diabetes and Exercise Study.

Cardiorespiratory fitness is inversely related to the development of type 2 diabetes and cardiovascular morbidity and mortality. Trials in individuals with impaired glucose tolerance have highlighted the role of physical activity/exercise in the prevention of type 2 diabetes. Moreover, physical activity and exercise training have been recognized as treatment options for patients with type 2 diabetes. Both aerobic and resistance training were shown to produce beneficial effects by reducing HbA(1c), inducing weight loss and improving fat distribution, lipid profile and blood pressure in patients with type 2 diabetes. Mixed aerobic and resistance training was recently shown to be more effective than either one alone in ameliorating HbA(1c). However, further research is needed to establish the volume, intensity and type of exercise that are required to reduce cardiovascular burden and particularly to define the best strategy for promoting long-term compliance and durable lifestyle changes in individuals with type 2 diabetes. The Italian Diabetes Exercise Study (IDES) is a prospective Italian multicentre randomized controlled trial, of larger size and longer duration than previously published trials. It has been designed to assess the combined effect of structured counselling and supervised mixed (aerobic plus resistance) exercise training, as compared with counselling alone, on HbA(1c) and other cardiovascular risk factors as well as fitness parameters in individuals with type 2 diabetes and the metabolic syndrome. This study was also aimed at testing a sustainable strategy for promoting and maintaining a sufficient level of physical activity among individuals with type 2 diabetes to be implemented at the population level.

Self glucose monitoring and physical exercise in diabetes.

Cardiorespiratory fitness, which is determined mainly by the level of physical activity, is inversely related to mortality in the general population as well as in subjects with diabetes, the incidence of which is also increased by low exercise capacity. Exercise is capable of promoting glucose utilization in normal subjects as well as in insulin-deficient or insulin-resistant diabetic individuals. In diabetic subjects treated with insulin or insulin secretagogues, exercise may also result in complications, with too much insulin causing hypoglycaemia and not enough insulin leading to hyperglycaemia and possibly ketoacidosis; both complications may also occur several hours after exercise. Therefore, self-monitoring of blood glucose before, during (for exercise duration of more than 1 h) and after physical exercise is highly recommended, and also carbohydrate supplementation may be required. In the Italian Diabetes Exercise Study (IDES), measurement of blood glucose and systolic and diastolic blood pressure levels before and after supervised sessions of combined (aerobic + resistance) exercise in type 2 diabetic subjects with the metabolic syndrome showed significant reductions of these parameters, though no major hypoglycaemic or hypotensive episode was detected. The extent of reduction of blood glucose was related to baseline values but not to energy expenditure and was higher in subjects treated with insulin than in those on diet or oral hypoglycaemic agents (OHA). Thus, supervised exercise training associated with blood glucose monitoring is an effective and safe intervention to decrease blood glucose levels in type 2 diabetic subjects.

Increased glomerular cell (podocyte) apoptosis in rats with streptozotocin-induced diabetes mellitus: role in the development of diabetic glomerular disease.

AIMS/HYPOTHESIS: Podocyte loss by apoptosis, in addition to favouring progression of established diabetic nephropathy, has been recently indicated as an early phenomenon triggering the initiation of glomerular lesions. This study aimed to assess the rate of glomerular cell death and its relationship with renal functional, structural and molecular changes in rats with experimental diabetes. METHODS: Male Sprague-Dawley rats with streptozotocin-induced diabetes and coeval non-diabetic control animals were killed at 7 days and at 2, 4 and 6 months for the assessment of apoptosis, renal function, renal structure and the expression of podocyte markers and apoptosis- and cell cycle-related proteins. RESULTS: Glomerular cell apoptosis was significantly increased in diabetic vs non-diabetic rats at 4 months and to an even greater extent at 6 months, with podocytes accounting for 70% of apoptosing cells. The increase in apoptosis was preceded by increases in proteinuria, albuminuria and mean glomerular and mesangial areas, and by reductions in glomerular cell density and content of synaptopodin and Wilms' tumour protein-1. It coincided with the development of mesangial expansion and glomerular sclerosis, and with the upregulation/activation both of tumour protein p53, which increased progressively throughout the study, and of p21 (also known as cyclin-dependent kinase inhibitor 1A, CIP1 and WAF1), which peaked at 4 months and decreased thereafter. CONCLUSIONS/INTERPRETATION: Glomerular cell (podocyte) apoptosis is not an early feature in the course of experimental diabetic glomerulopathy, since it is preceded by glomerular hypertrophy, which may decrease glomerular cell density to the point of inducing compensatory podocyte hypertrophy. This is associated with reduced podocyte protein expression (podocytopathy) and proteinuria, and ultimately results in apoptotic cell loss (podocytopenia), driving progression to mesangial expansion and glomerular sclerosis.

Chlamydia pneumoniae in PBMC: reproducibility of the OMPA nested touchdown PCR.

The aim of our study was to evaluate whether the replicate PCR testing may provide more accurate estimates of C. pneumoniae DNA prevalence in PBMC of patients undergoing carotid endarterectomy. Clinical sensitivity and reproducibility of ompA nested touchdown PCR was also performed. Clinical sensitivity and reproducibility was examined by testing C. pneumoniae-negative PBMC spiked with serial dilutions of semipurified C. pneumoniae elementary bodies (from 8 to 0.002 IFU/ml). Detection of C. pneumoniae DNA was performed by ompA nested touchdown PCR. Each clinical and spiked PBMC DNA specimen was analyzed in replicates of 1, 3, 5 and 10. PCR results of serial dilutions of C. pneumoniae DNA performed in replicates of 10 were analysed by probit analysis. C. pneumoniae DNA was detected in 14 of the 30 (46.7 %) PBMC clinical specimens examined when 10 replicates were tested. When we analyzed 1, 3 and 5 replicates, 4 (13.3 %), 7(23.3 %), 12(40 %) of the 30 specimens were positive, respectively. The limit of detection of ompA nested PCR touchdown was 0.008 IFU/ml when 10 replicates were tested. The ompA nested PCR had reproducibility scores of 10 for 10 from 8 to 4 IFU/ml concentration, but scores decreased for smaller numbers of IFU/ml. Our results showed that repeat testing of the same specimen increased clinical sensitivity as well as reproducibility of the ompA nested touchdown PCR. In conclusion the replicate PCR testing improves the performance of ompA nested touchdown PCR and provides a more accurate estimates of the prevalence of C. pneumoniae in PBMC of patients with atherosclerotic cardiovascular disease.