Effect of insulin glulisine on microvascular blood flow and endothelial function in the postprandial state

Treatment with insulin analogs and prevalence of cardiovascular complications in patients with type 1 diabetes

BACKGROUND

A lower incidence of cardiovascular events has been reported in type 2 diabetes patients treated with insulin analogs (IAs). Corresponding data on people affected by type 1 diabetes are not available yet.

METHODOLOGY

We investigated demographic and clinical data from 509 type 1 diabetics, who were treated in an outpatient clinic from 2006 to 2012. Multiple logistic regression was used to investigate the relationship between the type of insulin treatment and the prevalence of cardiovascular (CV) complications, that is, presence of coronary heart, cerebrovascular and peripheral arterial diseases, adjusting for potential confounders.

RESULTS

Results from multiple logistic regression revealed that patients with impaired renal function [estimated glomerular filtration rate (eGFR) < 90 ml/min] show lower CV complication rates when treated with IAs (25%) compared with patients treated with human insulin (HI; 28%) and HI/IA (38%, p = 0.06). CV complication rates in the complete patient collective amounted to 17% (IA), 21% (HI) and 21% (HI/IA, p = 0.08). Examination of CV complications according to the type of IA revealed the lowest complication rates in type 1 diabetics treated with insulin lispro (5.9%) and glargine (16%). However, complication rate differences among insulin treatments did not reach statistical significance.

CONCLUSION

The present cross-sectional study shows a borderline significantly lower CV morbidity in people with type 1 diabetes and impaired renal function when treated with IA compared with HI treatment after adjustment for multiple potential confounders [odds ratio (OR) = 0.78, which translates into a 22% lower complication rate]. Validation of these preliminary findings in confirmatory, prospective studies may have important clinical implications.

Effects of insulin analogs as an add-on to metformin on cutaneous microcirculation in type 2 diabetic patients

BACKGROUND

A single insulin injection was shown to improve microcirculatory blood flow. Our aim was to examine the effects of 4weeks of insulin therapy by three randomly assigned insulin analog regimens (Detemir, Aspart, and their combination) on cutaneous blood flow (CBF) and microcirculatory endothelial function as an add-on to metformin in type 2 diabetic patients poorly controlled on oral antidiabetic treatment.

METHODS

Fourty-two type 2 diabetic patients with no history of cardiovascular disease in secondary failure to oral antidiabetic agents had CBF measurements before and after acetylcholine (Ach) iontophoretic administration. CBF measurements were performed at fasting and after a standardized breakfast during the post-prandial period. Before randomization (Visit 1, V1) during the tests, participants took only metformin. The same tests were repeated after 4weeks of insulin treatment (Visit 2, V2).

RESULTS

Thirty-four patients had good quality recordings for both visits. During V1, CBF and CBF response to Ach increased in the post-prandial period. After 4weeks of insulin treatment, metabolic parameters improved. Compared to V1, CBF at fasting did not increase at V2 but there was an improvement in endothelial function at fasting after Ach iontophoresis, without difference across insulin regimens. Oxidative stress markers were not modified, and E-selectin and vascular cell adhesion molecule 1 levels decreased after insulin treatment, without differences between insulin groups.

CONCLUSIONS

A strategy of improving glycemic control for 4weeks with insulin analogs improves microcirculatory endothelial reactivity and reduces endothelial biomarkers at fasting, whatever the insulin regimen used. Insulin therapy associated to metformin is able to improve fasting microvascular endothelial function even before complete metabolic control.

Influence of insulin and glargine on outgrowth and number of circulating endothelial progenitor cells in type 2 diabetes patients: a partially double-blind, randomized, three-arm unicenter study

BACKGROUND

Endothelial progenitor cells (EPC) are bone marrow-derived cells which can undergo differentiation into endothelial cells and participate in endothelial repair and angiogenesis. Insulin facilitates this in vitro mediated by the IGF-1 receptor. Clinical trials showed that the number of circulating EPCs is influenced by glucose control and EPC are a predictor of cardiovascular death. To study direct effects of insulin treatment on EPCs in type 2 diabetes patients, add-on basal insulin treatment was compared to an escalation of oral medication aiming at similar glucose control between the groups.

METHODS

55 patients with type 2 diabetes (61.6±5.9 years) on oral diabetes medication were randomized in a 2:2:1 ratio in 3 groups. Patients were treated additionally with insulin glargine (n=20), NPH insulin (n=22) or escalated with oral medication (n=13). Number of circulating EPC, EPC-outgrowth, intima media thickness, skin microvascular function and HbA1c were documented at baseline and/or after 4 weeks and 4 months.

RESULTS

HbA1c at baseline was, 7.3+/-0.7% in the oral group, 7.3+/-0.9% and 7.5+/-0.7% in the glargine and NPH insulin respectively (p=0.713). HbA1c after 4 months decreased to 6.8+/-0.8%, 6.6+/-0.7% and 6.7+/-0.6%, in the oral, glargine and NPH insulin group respectively (p=0.61). FACS analysis showed no difference in number of circulating EPC between the groups after 4 weeks and 4 months. However, the outgrowth of EPCs as detected by colony forming assay was increased in the NPH insulin and glargine groups (29.2+/-6.4 and 29.4+/- 6.7 units respectively) compared to the group on oral medication (23.2+/-6.3, p=0.013) after 4 months of treatment. A significant decrease of IMT from 0.80mm (+/-0.14) at baseline to 0.76mm (+/-0.12) after 4 months could be observed in all patients only (p=0.03) with a trend towards a reduction of IMT after 4 months when all patients on insulin treatment were compared to the oral treatment group (p=0.06). Skin microvascular function revealed no differences between the groups (p=0.74).

CONCLUSION

The study shows that a 4-month treatment with add-on insulin significantly increases the outgrowth of EPC in patients with type 2 diabetes mellitus.

TRIAL REGISTRATION

(Clinical Trials Identifier: NCT00523393).

Standardized modulation of the injection site allows for insulin dose reduction without deterioration of metabolic control

OBJECTIVES

Use of an injection site modulation device (InsuPad) in intensive insulin treatment reduces frequency of hypoglycemia and prandial insulin requirements by enhancing subcutaneous microcirculation. This meal tolerance test (MTT) investigation was performed as a sub-study during the real-world BARMER study to demonstrate non-inferiority of the reduced insulin doses observed in this study with respect to metabolic control.

METHODS

The MTT was performed at baseline and after 3 months in insulin treated diabetes patients using the modulation device vs. a control group without device. The dose used for the MTT was individually calculated based on the prandial insulin records from the patient diaries before the test. Blood was drawn for determination of glucose, insulin, C-peptide, proinsulin, triglycerides, free fatty acids, nitrotyrosine, and asymmetric dimethyl-arginine (ADMA) at multiple time-points from 0 to 300 min. A total of 32 patients from one site were included into this MTT study (8 female, 7 type 1 diabetes, age: 49.9 ± 12.5 yrs, HbA1c: 7.2 ± 0.5%).

RESULTS

During the BARMER study, mean HbA1c was treated to target (<6.5%) in both groups. The prandial insulin dose decreased in the MTT modulation device group by -17.1%, but remained unchanged in the control group (-0.1%, p < 0.001). No change was seen for the basal insulin dose in both treatment arms. There were no differences between the groups with respect to the postprandial curves for glucose, C-peptide, intact proinsulin, free fatty acids, and triglycerides. Insulin absorption was faster with the modulation device (Tmax: 60 ± 28 min vs. 99 ± 46 min, p < 0.05). Key limitations are the small patient sample size and impossibility to determine the short-term effects of device use.

CONCLUSIONS

The results of this meal tolerance sub-study confirm that the observed prandial insulin dose reduction when using the injection site modulation device has no negative impact on postprandial metabolism.

In type 2 diabetes patients, insulin glargine is associated with lower postprandial release of intact proinsulin compared with sulfonylurea treatment

OBJECTIVE

Our objective was to investigate how postprandial processing of intact proinsulin is influenced by different pharmacological strategies in type 2 diabetes mellitus (T2DM).

MATERIALS/METHODS

This exploratory, nonrandomized, cross-sectional study recruited T2DM patients and healthy subjects. Upon recruitment, eligible T2DM patients had been treated for ≥6 months with insulin glargine (GLA) plus metformin (MET), sulfonylureas (SU) plus MET, or dipeptidyl-peptidase-4 inhibitors (DPP-4-I) plus MET. Blood samples were drawn from study participants after an 8 h fast and at regular intervals for up to 5 h after consumption of a standardized meal. Study endpoints included postprandial intact proinsulin and insulin levels and the insulin/proinsulin ratio.

RESULTS

As expected, postprandial secretion of proinsulin was greater in all T2DM treatment groups than in healthy subjects (p < .01 for all comparisons). Postprandial release of proinsulin was significantly greater in T2DM patients treated with SU plus MET than in those treated with GLA plus MET (p = .003). Treatment with DPP-4-I plus MET was associated with reduced proinsulin secretion versus SU plus MET and an increased insulin/proinsulin ratio versus the other T2DM groups.

CONCLUSIONS

Treatment of T2DM with GLA plus MET or DPP-4-I plus MET was associated with a more physiological postprandial secretion pattern of the β cell compared with those treated with SU plus MET.

Postprandial vascular effects of VIAject compared with insulin lispro and regular human insulin in patients with type 2 diabetes

OBJECTIVE

Recent studies suggested an impact of prandial insulin delivery on postprandial regulation of tissue blood flow. This study compared the effect of VIAject with human regular insulin and insulin lispro on postprandial oxidative stress and endothelial function in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Fourteen patients (seven men; aged 61.5 +/- 1.8 years; duration of diabetes 6.6 +/- 4.6 years; A1C 7.2 +/- 0.5% [mean +/- SEM]) received a prandial injection of VIAject, human regular insulin, and insulin lispro. At baseline and after a standardized liquid meal test (Ensure Plus), the postprandial increases in asymmetric dimethylarginine (ADMA) and nitrotyrosine levels were investigated. In addition, the postprandial effects on microvascular blood flow, skin oxygenation, and vascular elasticity were measured.

RESULTS

Treatment with VIAject resulted in a significant reduction in the peak postprandial generation of ADMA compared with human insulin and insulin lispro (VIAject -27.3 +/- 22.6, human insulin 97.7 +/- 24.4, and insulin lispro 66.9 +/- 33.9 nmol/l; P < 0.05, respectively). The postprandial increases in nitrotyrosine levels were significantly less after VIAject than after human regular insulin (VIAject -0.22 +/- 0.17 vs. human insulin 0.25 +/- 0.15 microg/ml; P < 0.05), whereas nitrotyrosine after insulin lispro was in between (insulin lispro 0.09 +/- 0.07 microg/ml; NS). In parallel, earlier and more pronounced increases in microvascular blood flow and skin oxygenation were obtained after VIAject compared with those after human insulin or insulin lispro (P < 0.05, respectively). All insulin formulations resulted in comparable improvements in central arterial elasticity. CONCLUSIONS; Treatment with VIAject reduced postprandial oxidative stress and improved endothelial function compared with human regular insulin or insulin lispro.

Insulin glulisine: a review of its use in the management of diabetes mellitus

Insulin glulisine (Apidra) is a human insulin analogue approved for the improvement of glycaemic control in adults, adolescents and children with diabetes mellitus. It has similar binding properties, and is associated with a faster onset but similar level of glucose disposal, to regular human insulin (RHI). Insulin glulisine and insulin lispro have similar effects on glucose levels. Insulin glulisine is effective when compared to other short- and rapid-acting insulins, demonstrating either noninferiority, no significant difference, or superiority in primary endpoints in studies involving patients with type 1 and type 2 diabetes. It is more effective and has a faster onset and shorter duration of activity than RHI. Insulin glulisine is as effective as insulin lispro in patients with type 1 diabetes; however, there is a need for further, well designed head-to-head comparisons with insulin lispro in patients with type 2 diabetes and with insulin aspart in patients with type 1 or type 2 diabetes to fully establish the place of insulin glulisine in the management of diabetes. Insulin glulisine has a flexible administration period, as it can be administered immediately before or after meals. Hypoglycaemia, a common risk with insulins, occurs at a similar rate among recipients of insulin glulisine to that seen with other insulins. Thus, insulin glulisine is an effective and well tolerated option for the treatment of patients with type 1 and type 2 diabetes.

Impaired microvascular perfusion: a consequence of vascular dysfunction and a potential cause of insulin resistance in muscle

Insulin has an exercise-like action to increase microvascular perfusion of skeletal muscle and thereby enhance delivery of hormone and nutrient to the myocytes. With insulin resistance, insulin's action to increase microvascular perfusion is markedly impaired. This review examines the present status of these observations and techniques available to measure such changes as well as the possible underpinning mechanisms. Low physiological doses of insulin and light exercise have been shown to increase microvascular perfusion without increasing bulk blood flow. In these circumstances, blood flow is proposed to be redirected from the nonnutritive route to the nutritive route with flow becoming dominant in the nonnutritive route when insulin resistance has developed. Increased vasomotion controlled by vascular smooth muscle may be part of the explanation by which insulin mediates an increase in microvascular perfusion, as seen from the effects of insulin on both muscle and skin microvascular blood flow. In addition, vascular dysfunction appears to be an early development in the onset of insulin resistance, with the consequence that impaired glucose delivery, more so than insulin delivery, accounts for the diminished glucose uptake by insulin-resistant muscle. Regular exercise may prevent and ameliorate insulin resistance by increasing "vascular fitness" and thereby recovering insulin-mediated capillary recruitment.