The effect of 8 years of strict glycaemic control on peripheral nerve function in IDDM patients: the Oslo Study

Prevalence of peripheral neuropathy with insulin-dependent diabetes mellitus

Insulin-dependent diabetes mellitus (IDDM) is rare in Chinese children. There have been no reports on the prevalence of peripheral neuropathy in Chinese children with IDDM. This study aimed to determine prevalence of subclinical peripheral neuropathy in Chinese children with IDDM. Motor and sensory nerve conduction studies of both median, ulnar, peroneal, and tibial (motor nerves) and median, ulnar, and sural (sensory nerves) were performed in 38 children with IDDM (18 males, 20 females). The age was 4-21 years (mean = 12.7 years; median = 12 years, 6 months). The duration of diabetes was less than 5 years in 15, 5-10 years in 14, and more than 10 years in nine. Neurophysiologic evidence of subclinical peripheral neuropathy was present in 26 patients (68.4%) of which motor, sensory, or motor and sensory involvement was 26 (68.4%), eight (21.1%), and 26 (68.4%), respectively. Twelve (31.6%) and 14 (36.8%) children had mild and moderate degrees of peripheral neuropathy, respectively. Among the 26 children with abnormal nerve-conduction studies, two (7.7%) had symptoms of numbness and pain in the lower limbs. Thus, two children had symptomatic neuropathy and most (n = 24) had asymptomatic peripheral neuropathy. Two children had systemic hypertension, and one (3.8%) had laboratory evidence of early renal complications. Analysis of demographic and laboratory risk factors for the development of subclinical peripheral neuropathy revealed that the age of onset, duration of diabetes, level of hemoglobin A1c, triglyceride, cholesterol, serum creatinine, and urea, microalbumin/creatinine ratio, and urinary microalbumin excretion rate were significantly related to the development of subclinical peripheral neuropathy in specific nerves.

Modern insulin therapy in children and adolescents

Clear evidence exists that near-normal blood glucose control will prevent serious late diabetic complications. This review summarizes the targets for blood glucose control and discusses why insulin replacement therapy is so complicated in children and adolescents. It is important that diabetes treatment teams have excellent knowledge of insulin preparations, insulin pharmacokinetics and action profiles and the limitations and pitfalls of therapy. This is necessary to be able to optimize and individualize treatment. A detailed summary of different insulin regimens is given and discussed to help treatment teams choose a suitable regimen for the individual patient. The use of home blood glucose measurement is necessary to reach the targets of treatment. If economic resources are limited, alternative strategies are suggested. In wealthy countries the lifestyle of adolescents demands great flexibility and a suggestion for systematic training to increase flexibility in daily life is presented.

The JEVIN trial: a population-based survey on the quality of diabetes care in Germany: 1994/1995 compared to 1989/1990

Since 1990 in most Eastern European countries health care systems have been decentralized or are undergoing the processes of decentralization. Increasingly, diabetic patients are no longer treated by diabetologists but by non-specialized physicians. During the same period structured treatment and teaching programmes have been introduced and health care is increasingly influenced by the St. Vincent declaration. To show the effect of these changes on the quality of diabetes care 90% (n = 244) of all insulin-treated diabetic patients aged 16 to 60 years and living in the city of Jena (100247 inhabitants) were studied in 1994/1995. The results were compared with the baseline examination of 1989/1990 (n = 190). HbA1c (HbA1c/mean normal) in IDDM patients under specialized care was similar in 1994/1995 (1.54 +/- 0.27, n = 47) to 1989/1990 (1.52 +/- 0.31, n = 131, p = 0.0018), but higher under non-specialized care (1.71 +/- 0.38, n = 80, p = 0.0087). In the total group of NIDDM patients there was no significant change in HbA1c (1994/1995: 1.75 +/- 0.4, n = 117, vs 1989/1990: 1.78 +/- 0.4, n = 59, p = 0.67), but with a tendency to higher HbA1c under non-specialized (1.81 +/- 0.4, n = 79) compared to specialized care (1.66 +/- 0.39, n = 38, p = 0.06). Incidence of severe hypoglycaemia (IDDM 0.13; NIDDM 0.04), ketoacidosis (0.02; 0.01) and the prevalence of nephropathy (21%; 35%) and neuropathy (24%; 38%) remained unchanged in comparison to 1989/1990, whereas there was an increase in the prevalence of diabetic retinopathy. Specialized care is mandatory for patients with IDDM.

Long-term effects of pancreatic transplantation on diabetic neuropathy

Restoration of a long-lasting euglycemic state by a functioning pancreatic transplantation (PTx) is the most logical treatment for insulin-dependent diabetes mellitus and for amelioration of secondary complications, including neuropathy. We evaluated neurological function by clinical examination, nerve conduction studies, and autonomic function tests in 115 patients with a functioning PTx and in 92 control patients treated with insulin, at baseline and 1, 2, 3.5, 5, 7, and 10 years later. In control patients, neuropathy progressively worsened during follow-up. The clinical examination score and composite indices of abnormality of motor and sensory nerve conduction decreased significantly at all intervals tested. Autonomic function indices also decreased, but significantly only after 1 year. In patients who received a successful PTx the neuropathy improved. The motor and sensory nerve conduction indices increased significantly at all intervals after transplantation, whereas the clinical examination and autonomic tests improved only slightly. Patients who received either a PTx alone, a PTx after a kidney graft, or simultaneous pancreatic and kidney transplantations improved similarly over the follow-up. These results indicate that a functioning PTx halts the progression and improves the signs of diabetic polyneuropathy by restoration of a normoglycemic state.

Insulin partially reverses deficits in peripheral nerve blood flow and conduction in experimental diabetes

Decreased nerve blood flow may be a pathogenetic factor in diabetic neuropathy. Previously it was shown that insulin treatment, commenced at the onset of streptozotocin-diabetes, prevents the development of a nerve blood flow deficit in the diabetic rat. The present study sought to determine the effect of short-term (one month) and acute (one hour) insulin reversal treatment on nerve blood flow deficits in streptozotocin-diabetes. Sciatic nerve blood flow was assessed using laser Doppler flowmetry. Treatment was initiated after one month of diabetes. One month of reversal insulin treatment ameliorated nerve laser Doppler flux (NDF) deficits; in untreated diabetic rats NDF was 51% of that in control animals (P < 0.01), in insulin-treated diabetic rats NDF was 85% of control values (P < 0.01 vs. untreated diabetic, P < 0.05 vs. control). In association with blood flow increases, we found a significant amelioration of motor (P < 0.05 vs. untreated diabetic) and sensory (P < 0.01 vs. untreated diabetic) nerve conduction velocities but not of exaggerated resistance to hypoxic conduction block. Insulin partially reversed hyperglycaemia and sciatic nerve polyol and sugar levels. In a second experiment, in rats with one month of diabetes, acute infusion of insulin led to a 47% (P < 0.001 vs. pre-insulin values) reduction of plasma glucose. This fall in plasma glucose was accompanied by a 38% (P < 0.05 vs. pre-insulin values) increase in NDF. Sensory nerve conduction velocity was marginally increased (6%, P < 0.05 vs. pre-insulin values) after insulin infusion, but motor conduction velocity was not. The data indicate that insulin can partially reverse deficits in nerve blood flow and conduction in diabetic rats.

The calcium hypothesis of brain aging and neurodegenerative disorders: significance in diabetic neuropathy

In this paper we discuss the possible role of disturbed neuronal calcium homeostasis in brain aging and diabetic neuropathy. Disturbances in the homeostasis of cytosolic calcium concentration have been implicated in the pathogenesis of various acute and chronic neurodegenerative disorders and in brain aging. Obviously, these disorders do not all share the same pathogenetic mechanisms. However, a number of the pathogenetic mechanisms involved have in common that they may ultimately cause loss of calcium homeostasis, leading to neuronal damage. By identifying the possible role of calcium, treatment strategies can be developed that may be effective in a variety of neurodegenerative disorders, despite differences in their pathogenesis. Our aim is to explore some of the similarities that exist between a number of processes that have been implicated in the pathogenesis of brain aging and diabetic neuropathy, including ischemia, oxidative stress and non-enzymatic protein glycosylation. Each of these factors might impair neuronal calcium homeostasis, and ultimately lead to neurodegenerative changes. By discussing the putative role of these specific factors in two apparently dissimilar disorders, such as brain aging and diabetic neuropathy, we obviously do not intend to suggest that their pathogenesis is one and the same. Instead, by examining the relative role of these factors in two different types of neurodegenerative disorders we would like to emphasize the importance of disturbances in cellular calcium homeostasis as a final common pathway in neuronal damage resulting from various noxious events.

Diabetic complications. The importance of glucose control

The most important question for clinicians caring for diabetic patients, and for the patient themselves, is whether the risk of complications can be altered by careful control of glycemia. Epidemiologic studies showed a strong relationship between glycemia and diabetic complications, in both type I and type II diabetes. There is a continuous relationship between prevailing glycemia and risk of progression of complications, implying that any improvement in glycemic control is beneficial. The debate of the question has ended--glucose control is important.

Peripheral, but not central, nervous system abnormalities are reversed by pancreatic islet transplantation in diabetic Lewis rats

Neuroelectrophysiological recordings represent a non-invasive and reproducible method of detecting central and peripheral nervous system alterations in diabetes mellitus. In order to evaluate whether the normalization of metabolic control obtained by pancreatic islet transplantation could reverse diabetic neuroelectrophysiological alterations, or prevent further deterioration, we used an experimental model in which pancreatic islets (n = 1200) were injected into the portal vein of inbred Lewis rats (used as islet donors as well as recipients). Islets were injected 4 months after diabetes induction, since previous work had shown functional but not morphological damage at the nervous tissue level at this stage of the disease. Visual (V), brainstem auditory (BA) and somatosensory (S) evoked potentials (EPs) were measured in streptozotocin-induced, islet-recipient diabetic rats (n = 7), streptozotocin-induced diabetic rats (n = 16) and non-diabetic control rats (n = 12). Metabolic parameters and electrophysiological recordings were evaluated before diabetes induction, before transplantation and 4 months later. After transplantation, glycaemic levels returned to normal values within 1 week and remained so until the end of the study, as confirmed by a normal oral glucose tolerance test and by an increase in body weight. Electrophysiological recordings were altered in diabetic animals before transplantation. Four months after transplantation EP recordings improved, with a detectable gradient from the peripheral to the central structures. SEPs were significantly improved in the peripheral tarsus-L6 tract and the L6-cortex tract (P < 0.005 and P < 0.01 versus diabetic rats) and were ameliorated without achieving statistical significance in the central L6-cortex tract. BAEP latency values tended to improve in transplanted rats, but the differences versus non-transplanted diabetic animals failed to reach significance. VEP values remained clearly pathological and even deteriorated after transplantation. These results show that normalization of metabolic control by pancreatic islet transplantation can reverse some of the already established neuroelectrophysiological alterations at the peripheral nervous system level, but does not affect other alterations at the central nervous system level.

Severe hypoglycemia in insulin-dependent diabetic children treated by multiple injection insulin regimen

The occurrence and risk factors of severe hypoglycemic attacks were analyzed during a 4-year study in a group of children and adolescents who received human insulin and followed a multiple daily injection regimen (three or four injections per day); 29 patients experienced severe hypoglycemia at least once in 4 years. Of these, 13 suffered recurrent episodes: 8 had two episodes, 4 had four episodes, and 1 patient had seven episodes. For comparative purposes, the nonhypoglycemic population (217 diabetic children) was used as a control group. The hypoglycemic children received insulin doses which were significantly higher than for nonhypoglycemic patients (1.05 +/- 0.6 U/kg daily vs 0.87 +/- 0.7; P < 0.05). Moreover, the hypoglycemic group had a significantly higher mean number of previous episodes of severe hypoglycemia than the nonhypoglycemic group (0.98 +/- 1.2 vs 0.26 +/- 0.7; P < 0.001). There was no significant difference in age, sex, duration of disease, and metabolic control between hypoglycemic and nonhypoglycemic children. There was no association between severe hypoglycemia and the presence of retinopathy, persistent microalbuminuria, or autonomic neuropathy. Severe hypoglycemia is a recurrent problem, not related to the quality of metabolic control nor to the presence of long-term microvascular complications, and diabetic children with a personal history of severe hypoglycemia are at risk for future episodes.

Autonomic dysfunction in newly diagnosed insulin-dependent diabetes mellitus children

In order to evaluate the presence of electrophysiologic signs of autonomic dysfunction (AD) in newly diagnosed diabetic children, cardiovascular reflex tests were performed in 55 (30 female, 25 male) newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients aged 10.3-20.7 years (mean +/- S.D.: 15.2 +/- 5.6). Ten (18.2%) diabetic children had cardiovascular AD, defined as abnormal results in 2 of 5 tests. Autonomic function tests were assessed at entry and after 12, 24, and 36 months of the study. All diabetic children received human insulin and followed an intensive insulin treatment (3 or 4 injections per day), associated with a teaching program of self-management of the disease. In the 3 years of follow-up, all children improved the quality of metabolic control (glycosylated hemoglobin, HbA1c: 10.3 +/- 1.1% versus 7.7 +/- 0.9; P < .01) and manifested no significant difference between baseline and follow-up values of autonomic function tests which remained unchanged in spite of this improvement. Cardiovascular autonomic dysfunction can be present in newly diagnosed IDDM children and it seems to be stable in children who follow an intensive insulin injection therapy.

Autonomic neuropathy in diabetic children

OBJECTIVE

Evaluate the presence of cardiovascular autonomic nerve dysfunction in children and adolescents with insulin-dependent diabetes mellitus.

METHODOLOGY

We studied 110 patients (54 male, 56 female) and 100 healthy sex and age-matched children. Autonomic nerve function was assessed by standard cardiovascular reflex tests: (1) Fall in systolic blood pressure in response to standing. (2) Heart rate in response to standing. (3) Beat-to-beat rate variation during deep breathing. (4) Quotient of heart rate during and after Valsalva manoeuvre. (5) Change in blood pressure response to sustained handgrip. The coefficient of variation of heart rate was determined from 150 systoles using a microcomputer-based technique. The lower limits of normal were defined according to statistical analysis taking into account the relationship between heart rate variability and age.

RESULTS

Forty-seven of the 110 diabetic children and adolescents studied showed one or more abnormal tests for cardiovascular autonomic dysfunction; many patients had an abnormality in more than one test. Twenty-two patients showed early involvement, 18 patients had definite and 7 severe involvement. No correlation was found between sex, glycaemic control, duration of diabetes or presence of retinopathy and persistent microalbuminuria and the autonomic nerve function.

CONCLUSIONS

In the paediatric age group also, autonomic nerve dysfunction can be present in asymptomatic diabetic patients. Heart rate variation during Valsalva manoeuvre and maximum/minimum 30:15 ratio are the most sensitive indices to detect autonomic abnormalities in children.

Subclinical nerve dysfunction in children and adolescents with IDDM

The purpose of this study was to investigate whether young insulin-dependent diabetic patients still develop peripheral nerve dysfunction when using modern multiple insulin injection therapy and to elucidate if this correlated with various disease parameters. Seventy-five patients, 7 to 20 years old with a duration of diabetes of more than 3 years, and 128 age-matched healthy control subjects underwent bilateral studies of median, peroneal, and sural nerves. Presence of diabetes lowered motor conduction velocity (p < 0.0001), sensory conduction velocity (p < 0.0001) and sensory nerve action potential (p < 0.05) in all examined nerves. The mean change in conduction velocity induced by diabetes was -4.8 m/s in the peroneal nerve, -3.3 m/s in the median motor nerve, -2.6 m/s in the sural nerve and -2.4 m/s in the median sensory nerve. Fifty-seven percent of the patients had abnormal conduction (values outside 95% predictive interval) which was seen most often in the motor nerves, especially in the peroneal nerve (41%) followed by the median nerve (24%). In multiple regression analysis, long-term poor metabolic control and increased body length correlated with nerve dysfunction identified in most examined parameters. Three patients had signs or symptoms suggestive of neuropathy. It is concluded that despite modern multiple insulin injection therapy, with reasonably good metabolic control, nerve dysfunction is still common in children and adolescents with insulin-dependent diabetes mellitus. Risk factors are increased height and long-term poor metabolic control.