Influence of continuous subcutaneous insulin infusion (CSII) treatment on diabetic somatic and autonomic neuropathy

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.

C-peptide improves autonomic nerve function in IDDM patients

In order to determine the possible influence of C-peptide on nerve function, 12 insulin-dependent diabetic (IDDM) patients with symptoms of diabetic polyneuropathy were studied twice under euglycaemic conditions. Tests of autonomic nerve function (respiratory heart rate variability, acceleration and brake index during tilting), quantitative sensory threshold determinations, nerve conduction studies and clinical neurological examination were carried out before and during a 3-h i.v. infusion of either C-peptide (6 pmol.kg-1.min-1) or physiological saline solution in a double-blind study. Plasma C-peptide concentrations increased from 0.11 +/- 0.02 to 1.73 +/- 0.04 nmol/l during C-peptide infusion. Clinical neurological examination quantitative sensory threshold evaluations and nerve conduction measurements failed to detect significant changes between C-peptide and saline study periods. Respiratory heart rate variability increased significantly from 13 +/- 1 to 20 +/- 2% during C-peptide infusion (p < 0.001), reaching normal values in five of the subjects; control studies with saline infusion did not alter the heart rate variability (basal, 14 +/- 2; saline, 15 +/- 2%). A reduced brake index value was found in seven patients and increased significantly during the C-peptide infusion period (4.6 +/- 1.0 to 10.3 +/- 2.2%, p < 0.05) but not during saline infusion (5.9 +/- 2 to 4.1 +/- 1.1%, NS). It is concluded that short-term (3-h) infusion of C-peptide in physiological amounts may improve autonomic nerve function in patients with IDDM.

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.

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

We have investigated the effect of long-term strict glycaemic control on peripheral and autonomic nerve function in 45 IDDM patients (age 18-42 years, diabetes duration 7-23 years) without clinical signs of neuropathy or other neurological disease. They were randomly assigned to treatment either with continuous insulin infusion, multiple injections (4-6 times daily), or conventional treatment (twice daily) for 4 years and followed prospectively for 8 years. Motor and sensory nerve conduction velocities were measured at the start and after 8 years. Autonomic nerve function tests were performed only once, after 8 years. A significant reduction of nerve conduction velocity was observed during 8 years in patients with mean HbA1 more than 10% (n = 12, group mean 10.9%, range 10.1-13.2%) compared to patients with HbA1 less than 10% (n = 33, group mean 9.0%, range 7.5-9.9%). Change of motor nerve conduction velocity in the peroneal nerve was: -4.8 +/- 4.9 (SD) vs -2.2 +/- 5.3 m/s (p < 0.01). Change of motor nerve conduction velocity in the posterior tibial nerve was: -6.8 +/- 5.7 vs- 3.9 +/- 5.1 m/s (p < 0.05). No significant changes were observed in the ulnar nerve. Change of sensoric nerve conduction velocity in the sural nerve was: -8.9 +/- 8.0 vs -4.6 +/- 5.3 m/s (p < 0.05). Multiple regression analysis showed that a change in HbA1 of 1% resulted in a 1.3 m/s change in nerve conduction velocity during 8 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of pancreatic and/or renal transplantation on diabetic autonomic neuropathy

Thirty-nine Type 1 (insulin-dependent) diabetic patients were studied prospectively after simultaneous pancreas and kidney (n = 26) and kidney grafting alone (n = 13) by measuring heart rate variation during various maneuvers and answering a standardized questionnaire every 6 to 12 months post-transplant. While age, duration of diabetes, and serum creatinine (168.1 +/- 35.4 vs 132.7 +/- 17.7 mumol/l) were comparable, haemoglobin A1 levels were significantly lower (6.6 +/- 0.2 vs 8.5 +/- 0.3%; p less than 0.01) and the mean observation time longer (35 +/- 2 vs 25 +/- 3 months; p less than 0.05) in the pancreas recipients when compared with kidney transplanted patients. Heart rate variation during deep breathing, lying/standing and Valsalva manoeuver were very similar in both groups initially and did not improve during follow-up. However, there was a significant reduction in heart rate in the pancreas recipient group. Autonomic symptoms of the gastrointestinal and thermoregulatory system improved more in the pancreas grafted subjects, while hypoglycaemia unawareness deteriorated in the kidney recipients. This study suggests that long-term normoglycaemia by successful pancreatic grafting is able to halt the progression of autonomic dysfunction.

A multicentre trial of the aldose-reductase inhibitor, tolrestat, in patients with symptomatic diabetic neuropathy

The effects of the aldose-reductase inhibitor, tolrestat, on chronic symptomatic diabetic sensorimotor neuropathy were studied during a placebo-controlled, randomised, 52-week multicentre trial. Of the four tolrestat doses investigated, only the highest dose group, 200 mg once daily, showed subjective and objective benefit over baseline and placebo, and further analyses are confined to this group (n = 112) and placebo (n = 107). Painful and paraesthetic symptoms were analysed separately: improvement in paraesthetic symptoms were seen at one year (p = 0.04), though painful symptoms improved on both placebo and active therapies. Significant improvement in both tibial and peroneal motor nerve conduction velocities were seen at 52 weeks. Tolrestat 200 mg once daily was significantly better than placebo in producing concordant improvements in both motor nerve conduction velocities and paraesthetic symptom scores at 24 weeks (p = 0.01), 42 weeks (p = 0.01) and 52 weeks (p = 0.02). Long-term benefit [concordant improvement at 24 weeks maintained until 52 weeks] was seen in 28% of treated patients compared to 5% on placebo (p = 0.001). It is concluded that some sustained improvement in symptomatic diabetic neuropathy may be obtained following aldose-reductase inhibition with tolrestat 200 mg once daily.

Effects of pancreatic transplantation on diabetic neuropathy

Reestablishment of the euglycemic state by successful transplantation of the pancreas might halt or reverse diabetic neuropathy. To test this possibility we evaluated neurologic function by clinical examination, nerve conduction studies, and autonomic-function tests in patients with insulin-dependent (Type I) diabetes mellitus before and after successful pancreatic transplantation. Sixty-one patients were studied before and 12 months after transplantation, 27 again after 24 months, and 11 again after 42 months. A control group of patients with Type I diabetes treated with insulin underwent the same studies at similar intervals--48 patients before and after 12 months had elapsed, 21 again after 24 months, and 12 again after 42 months. In the control group, neuropathy tended to worsen during the follow-up period. The scores on the clinical examination indicated increased impairment after 12 months. Composite indexes of the degree of abnormality found on neurophysiologic testing of the function of peripheral motor, sensory, and autonomic nerves indicated decreased autonomic function after 12 months. The examination score and the three index values worsened slightly but not significantly in the patients followed for 24 and 42 months. In contrast, in the patients who had received pancreatic transplants, the neuropathy tended to improve. There was significant improvement in the motor and sensory indexes 12 months after transplantation and in the sensory index 24 months after transplantation. The other measures improved slightly but not significantly at these times, as did all four measures in the patients studied 42 months after transplantation. We conclude that the progression of diabetic polyneuropathy may be halted through the restoration of a euglycemic state by successful pancreatic transplantation.

Reduced intraindividual variability of repeated cardiovascular reflex tests: an additional marker of autonomic neuropathy in insulin-dependent (type I) diabetes mellitus?

The particular questions asked in our study were: 1. does the individual reproducibility of the cardiovascular reflex tests differ between healthy controls and patients suffering from type I diabetes mellitus and 2. if there is a difference, do the different cardiovascular reflexes vary in this regard? Nine healthy controls (4 women, 5 men, age 31 +/- 2.1 years) and 11 type I diabetics (4 women, 7 men, age 30.9 +/- 5.6 years, duration of diabetes 3.23 years) underwent the following tests 6 times in a 12-h period (07:00 to 19:00): variation of heart rate during deep breathing (E/I ratio), variation of heart rate during lying and standing (tachycardia/bradycardia or 30/15 ratio), Valsalva maneuver (Valsalva ratio), response of diastolic blood pressure to sustained hand grip, and response of systolic blood pressure to posture. The test results did not indicate a diurnal fluctuation nor were they systematically influenced by antecedent insulin injections or meals, either in diabetic patients or in healthy controls. The 11 diabetics had significantly lower intraindividual variations of E/I and Valsalva ratios than the controls (p less than 0.05, p less than 0.001, respectively). In the diabetics with parasympathetic failure the intraindividual variabilities of all cardiovascular reflex responses were lower than those of the patients with an intact autonomic nervous system as well as those of the control subjects. On the contrary, in the diabetic patients without autonomic neuropathy, only the intraindividual variability of the Valsalva maneuver was significantly attenuated (p less than 0.025), compared with the healthy volunteers. To conclude, the more pathological the single test result, the greater is its reproducibility and its clinical significance.

Reproducibility of cardiovascular autonomic tests in diabetics with and without autonomic dysfunction and in normal controls

The present study evaluates the reproducibility of five cardiovascular reflex tests, deep breathing (DB), Valsalva maneuver (VM), sustained hand-grip (SHG), postural hypotension (PH) and lying to standing (LS) in normal subjects and in insulin dependent (type I) diabetic patients. The study was carried out in 10 normal subjects, in 10 diabetics with autonomic neuropathy and in 10 diabetics without autonomic neuropathy. The five cardiovascular reflex tests were performed five times on five consecutive days by the same investigator and in identical basal conditions. The intraindividual variability of DB, LS and VM was significantly reduced in diabetics with autonomic neuropathy compared with normal controls, but there was no difference between diabetics without neuropathy and normal controls. The intraindividual variability of PH was significantly increased in diabetics with autonomic neuropathy compared with diabetics without autonomic neuropathy and with normal controls. There was no difference among the three groups in the reproducibility of SHG. In normal subjects the intraindividual variability only exceptionally produced a shift from normal to abnormal values or vice versa; in diabetics with autonomic neuropathy this shift was more frequent.

Management of diabetes mellitus

The past decade has seen a rapid advancement in our understanding of diabetes and in our ability to treat it. A new diagnostic classification has been established. Guidelines for diet therapy have been revised. New oral hypoglycemic agents have been approved for use, and the rationale for using oral agents expanded. Insulin therapy has been expanded by development of human insulin and new modes of injection, including insulin pumps. Several new techniques are available for monitoring control of diabetes.