Prevalence of morning hyperglycaemia: determinants of fasting blood glucose concentrations in insulin-treated diabetics

Insulin pump dosing across gestation in women with well-controlled type 1 diabetes mellitus

OBJECTIVE

We hypothesized that bolus and basal insulin doses in women with type 1 diabetes mellitus who use insulin pumps would increase 2-fold to maintain hemoglobin A1c <6.5% across gestation.

STUDY DESIGN

This was a retrospective study of 9 women with type 1 diabetes mellitus with preconceptional hemoglobin A1c ≤ 7.4% using insulin pumps. The primary outcome was absolute and percentage change of basal and bolus insulin from preconception to delivery.

RESULTS

Total daily dose of insulin increased from 33.3 ± 7.8 U/d before conception to 93.5 ± 27.9 U/d at delivery. Basal rates rose modestly (50% increase, from 16.2 ± 6.5 U/d to 24.0 ± 9 U/d); bolus insulin doses quadrupled from 17.1 ± 6.1 U/d to 69.5 ± 29.6 U/d (P = .0001). Bolus insulin increased from approximately 50% of total daily dose of insulin before conception to 75% of total daily dose of insulin at 36 weeks' gestation.

CONCLUSION

In well-controlled type 1 diabetes mellitus, insulin requirements increased 3-fold from before conception to 36 weeks' gestation. Most of this requirement was attributed to an increase in bolus rates that are required for control with meals.

Immunological responses to exogenous insulin

Regardless of purity and origin, therapeutic insulins continue to be immunogenic in humans. However, severe immunological complications occur rarely, and less severe events affect a small minority of patients. Insulin autoantibodies (IAAs) may be detectable in insulin-naive individuals who have a high likelihood of developing type 1 diabetes or in patients who have had viral disorders, have been treated with various drugs, or have autoimmune disorders or paraneoplastic syndromes. This suggests that under certain circumstances, immune tolerance to insulin can be overcome. Factors that can lead to more or less susceptibility to humoral responses to exogenous insulin include the recipient's immune response genes, age, the presence of sufficient circulating autologous insulin, and the site of insulin delivery. Little proof exists, however, that the development of insulin antibodies (IAs) to exogenous insulin therapy affects integrated glucose control, insulin dose requirements, and incidence of hypoglycemia, or contributes to beta-cell failure or to long-term complications of diabetes. Studies in which pregnant women with diabetes were monitored for glycemic control argue against a connection between IAs and fetal risk. Although studies have shown increased levels of immune complexes in patients with diabetic microangiopathic complications, these immune complexes often do not contain insulin or IAs, and insulin administration does not contribute to their formation. The majority of studies have shown no relationship between IAs and diabetic angiopathic complications, including nephropathy, retinopathy, and neuropathy. With the advent of novel insulin formulations and delivery systems, such as insulin pumps and inhaled insulin, examination of these issues is increasingly relevant.

The effect of insulin antibodies on the metabolic action of inhaled and subcutaneous insulin: a prospective randomized pharmacodynamic study

OBJECTIVE

To assess the impact of the development of high- or low-affinity insulin antibodies (IABs) on postprandial glucose tolerance, duration of insulin action, and clinical safety in patients with type 1 diabetes receiving inhaled insulin (Exubera).

RESEARCH DESIGN AND METHODS

This study consisted of a prospective, randomized, open-label, parallel-group trial in which 47 patients with type 1 diabetes received NPH insulin twice daily plus either premeal inhaled insulin (INH group; n = 24) or pre-meal subcutaneous regular insulin (SC group; n = 23) for 24 weeks. Meal challenge and euglycemic clamp studies were performed on consecutive days at baseline, week 12, and week 24. Adverse events were monitored.

RESULTS

For the INH and SC groups, mean (+/-SD) IAB levels were 3.5 +/- 3.9 and 2.6 +/- 4.1 muU/ml at baseline, respectively, compared with 101.4 +/- 140.4 and 4.3 +/- 9.4 microU/ml at week 24. At week 24, the changes from baseline were similar for the INH and SC groups for maximal plasma glucose concentration (C(max)) (adjusted ratio for treatment group difference 0.99 [90% CI 0.95-1.03]), area under the plasma glucose concentration time curve (adjusted ratio for treatment group difference 0.98 [0.88-1.08]), and duration of insulin action (adjusted treatment group difference 29 min [-49 to 108]). No adverse events were attributed to IABs.

CONCLUSIONS

In patients with type 1 diabetes treated with inhaled insulin, development of high- or low-affinity IABs did not impair postprandial glucose tolerance, alter the time-action profile of insulin, or impact tolerability. No clinical relevance of IABs was identified in this study.

An overview of insulin glargine

Insulin glargine is an innovative, long-acting human insulin analogue, whose prolonged mean activity profile has no pronounced peak. Accordingly, it mimics more closely the natural physiological profile of basal endogenous insulin secretion than do traditional extended-acting insulins such as NPH insulin. As would be expected for a more satisfactory basal insulin, clinical trials comparing insulin glargine with NPH insulin show less nocturnal hypoglycaemia, improved pre-breakfast blood glucose levels, or both. Furthermore, no substantive safety concerns have emerged for insulin glargine. Thus, insulin glargine represents the first major advance in the provision of basal insulin injection therapy for people with type 1 and type 2 diabetes for over 50 years.

Therapeutic targets in the management of Type 1 diabetes

For historical reasons, diabetes has long been linked with blood and urine glucose control, partly because these were clearly linked to acute symptoms, and partly because glucose became measurable around 200 years ago. Today it is recognized that there is far more to diabetes than simply monitoring symptoms and blood glucose. Intensive management has an impact on the quality of life. Late complications have their own risk factors and markers. Monitoring and early detection of these risk factors and markers can lead to changes in treatment before tissue damage is too severe. Accordingly, professionals now find themselves monitoring a range of adverse outcomes, markers for adverse outcomes, risk factors and risk markers for microvascular and arterial disease, acute complications of therapy, and the care structures needed to deliver this. Adverse outcomes lend themselves to targets for complication control in populations, and markers of adverse outcomes (such as retinopathy and raised albumin excretion rate) in treatment cohorts. Surveillance systems will have targets for yearly recall and review of early complications. Metabolic (surrogate) outcomes can be monitored in individual patients, but monitoring is only of value in so far as it guides interventions, and this requires comparison to some intervention level or absolute target. Even for blood glucose control this is not easy, for conventional measures such as glycated haemoglobin have their own problems, and more modern approaches such as post-prandial glucose levels are controversial and less convenient to measure. In many people with type 1 diabetes targets for blood pressure, LDL cholesterol, and serum triglycerides will also be appropriate, and need to be part of any protocol of management.

Blood glucose control on Sunday in IDDM patients: intensified conventional insulin therapy versus continuous subcutaneous insulin infusion

We have assessed the capacity of continuous subcutaneous insulin infusion (CSII) to maintain good blood glucose metabolic control on Sundays, when waking is delayed, with reference to intensified conventional insulin therapy by multiple daily injections (MDI). The study lasted 3 weeks, including 3 week-ends. A total of 20 IDDM patients were selected for metabolic control: ten were treated by CSII and ten by MDI. Blood glucose was determined at least three times a day (fasting on waking, pre-lunch and pre-dinner). The times of blood glucose determinations and their values were recorded in a memory reflectance meter. Waking, the first blood glucose measurement and the first insulin injection (MDI) or bolus (CSII) were about 1 h later on Sundays than on a weekday (44 +/- 4 min in MDI group, P < 0.04; and 59 +/- 7 min in CSII group, P < 0.02). The times of the pre-lunch and pre-dinner blood glucose determinations were not significantly different. The mean waking and pre-lunch blood glucose values of the MDI group were higher on Sundays (11.5 +/- 3.8 and 9.7 +/- 4.5 mmol/l) than on weekdays (8.7 +/- 2.3 and 7.1 +/- 2.5 mmol/1)(P < 0.01). The pre-prandial blood glucose levels of the CSII group on Sundays and weekdays were not statistically different at any time. Changes in the waking time and the subsequent delay in the first insulin bolus on Sunday may alter blood glucose control in patients on MDI, but CSII allows such changes without any glycemic side effects.

Human isophane or lente insulin? A double blind crossover trial in insulin dependent diabetes mellitus

Fifty two children with insulin dependent diabetes mellitus were randomised to receive human isophane or lente insulin preparations in combination with soluble insulin in a double blind trial. Patients were seen every two months, and crossed over after four months of treatment. Control assessed by glycated haemoglobin was significantly lower in children on human isophane insulin, but fasting blood glucose and fructosamine concentrations and the number of episodes of hypoglycaemia were similar on both regimens. In five children on twice daily insulin regimens, insulin profiles throughout a 24 hour period demonstrated greater variability on lente compared with isophane insulin despite identically administered insulin doses. A questionnaire completed at the end of the study showed that two thirds of the children and/or their parents preferred the isophane insulin, and they gave perceived improvement of metabolic control as the major reason for their choice.

Early morning glycaemia and the metabolic consequences of delaying breakfast/morning insulin. A comparison of continuous subcutaneous insulin infusion and multiple injection therapy with human isophane or human ultralente insulin at bedtime in insulin-dependent diabetics

We studied morning glycaemia and metabolic consequences of delaying morning insulin/breakfast in insulin-dependent diabetics on (i) continuous subcutaneous insulin infusion (CSII) (n = 27), (ii) multiple-injection therapy (MI) with human isophane insulin at bedtime (MI/human isophane) (n = 23) and (iii) MI with human ultralente insulin at bedtime (MI/human ultralente) (n = 14). After an overnight fast, food and insulin (except for the basal infusion on CSII) were withheld, and blood glucose, serum free insulin and serum betahydroxybutyrate were followed from 0800 hours to 1300 hours. At all times blood glucose was lowest on CSII, intermediate on MI/human isophane and highest on MI/human ultralente; serum free insulin was highest on CSII, intermediate on MI/human ultralente and lowest on MI/human isophane; serum betahydroxybutyrate was lowest on CSII, intermediate on MI/human ultralente and highest on MI/human isophane. Blood glucose rose significantly on MI/human isophane (p less than 0.001) and CSII (p less than 0.02); serum free insulin declined significantly on MI/human isophane (p less than 0.001), and betahydroxybutyrate rose significantly on all regimens. Morning metabolic control is better with CSII than MI. Human isophane insulin is preferable to human ultralente insulin overnight in MI. Delaying morning insulin is not advisable on intensified insulin regimens, being most unfavourable with MI/human isophane.

A comparison of human ultralente- and lente-based twice-daily injection regimens

The problem of fasting hyperglycaemia remains unresolved on currently used twice-daily injection regimens. Human ultralente insulin is of longer duration than human lente and differs from it only in the nature of the zinc-insulin complex. In a 6-month double-blind crossover study these insulins were compared in 66 patients who were randomized to human ultralente or human lente insulin given together with human soluble insulin in a twice-daily injection regimen. Patients were seen monthly and crossed over after 3 months treatment. Fasting blood glucose concentrations on the ultralente regimen were considerably lower than on the lente regimen, the difference being statistically significant (6.6 +/- 0.5 vs 8.2 +/- 0.5 mmol l-1, p less than 0.05), but only present in those patients with fasting concentrations below the median. Glycosylated haemoglobin was identical on both regimens (9.3 +/- 0.2%). The evening ultralente dose was slightly but significantly lower than the evening lente dose (14.9 +/- 0.8 vs 15.5 +/- 0.8 U, p less than 0.05) thus endorsing the lowering effect of ultralente on the fasting blood glucose concentration. However, the incidence of serious hypoglycaemic events was higher on the ultralente regimen (0.38 +/- 0.10 vs 0.09 +/- 0.04 events per patient-month, p less than 0.02), the majority of nocturnal events occurring between 0500 h and breakfast. We conclude that ultralente insulin can give an improved fasting blood glucose concentration but that in those patients with more marked fasting hyperglycaemia or with a nocturnal hypoglycaemia problem it offers no clinical advantage over human lente insulin in a twice-daily injection regimen.

Does the measurement of serum fructosamine accurately reflect levels of glycated albumin in insulin-dependent diabetes?

We have measured serum glycated albumin (GSA) by affinity chromatography and immunoturbidimetry, and serum fructosamine using a Cobas FARA analyser in blood samples from 37 type I diabetics and 21 healthy controls. Random blood glucose and glycated haemoglobin levels were also measured. Glycated haemoglobin (HbA1) correlated with glycated albumin and fructosamine in the diabetic group. A less clear relationship was found between glycated albumin and fructosamine. HbA1, GSA and fructosamine correlated poorly with random blood glucose levels. These data indicate that serum fructosamine levels do not accurately reflect those of glycated albumin, as has recently been suggested, in type I insulin-dependent diabetics where glycaemic control fluctuates more than in type II diabetics. It is postulated that the two methods reflect varying glycaemic levels to a different degree, thereby accounting for the disparity.

A comparison of premixed with patient-mixed insulins

Blood glucose control in 12 C-peptide negative patients has been compared in a crossover trial of four insulin treatment regimens: porcine soluble and isophane, premixed porcine soluble/isophane, porcine soluble and lente, all taken twice daily, and once daily bovine ultralente with three porcine soluble injections before meals. Each regimen lasted 8 weeks and included home blood glucose monitoring, telephoned advice on dose adjustment during the first 2 weeks, and home collection of seven-point capillary blood profiles for laboratory analysis. No significant differences between the regimens could be demonstrated when HbA1c, 24 h mean blood glucose, and M-values were evaluated. The average range of blood glucose values for four capillary samples taken at the same time point on different days was 8.0 mmol/l, compared with a maximum difference between regimens of 3.6 mmol/l at any time point, suggesting that blood glucose control is more heavily influenced by erratic insulin absorption than by the insulin regimen chosen. Premixed insulins offer convenience of use without significant deterioration of blood glucose control.

Two or three insulin injections in adolescence?

Morning hyperglycaemia remains a challenge to conventional insulin regimens. Eighteen adolescents participated in a one year crossover study to examine the effect of delaying the evening intermediate acting insulin from before the evening meal to bedtime. This three injection regimen caused slightly higher blood glucose concentrations in the early part of the night, and lower concentrations in the morning, but no overall change in glycosylated haemoglobin concentrations (HbA1c). Seasonal change accounted for substantially more of the variance in HbA1c concentrations than did the regimen change. The three injection regimen did not alter the frequency of hypoglycaemic episodes. Metabolic control on both regimens might have been improved by more intensive monitoring and medical attention. This study suggests that factors beyond medical control, such as seasonal variation, may contribute more to the control of diabetes in adolescents than changes in conventional insulin regimens, particularly when unaccompanied by intensive monitoring.