Abnormal secretion of insulin and glucagon by the in vitro perfused pancreas of the genetically diabetic Chinese hamster.

Hereditary insulin-deficient diabetes mellitus occurs in certain sublines of nonobese Chinese hamsters. Several characteristics of this syndrome are similar to those seen in insulin-deficient human diabetics. Therefore, to characterize pancreatic islet function, dynamic insulin and glucagon release from normal and nonketotic diabetic hamster pancreases in response to glucose (300 mg/100 ml) and theophylline (10 mM), infused singly and together, was studied in vitro.20-min glucose infusions of normal hamster pancreases caused biphasic insulin release, consisting of a rapid first peak and a gradually rising second phase, similar to that reported for man in vivo. Both phases were significantly reduced in the diabetic pancreases. Theophylline alone stimulated similar nonphasic insulin release in both the normal and the diabetic pancreases. Glucose and theophylline together caused greater insulin release than either stimulant alone in both normals and diabetics; however, the diabetic response was still subnormal. Glucose suppressed glucagon release from normal pancreases; suppression was significantly impaired in diabetics. Theophylline stimulated nonphasic glucagon release in both the normals and diabetics. Glucose partially suppressed the theophylline-stimulated release in both groups.Insulin/glucagon molar ratios of the diabetics were consistently subnormal, although individual hormone levels often overlapped into the normal range. IN SUMMARY, THE PANCREASES OF GENETICALLY DIABETIC CHINESE HAMSTERS PERFUSED IN VITRO SHOWED: (a) decreased first and second phase insulin release in response to glucose-containing stimuli-only partially ameliorated by theophylline-, and (b) impaired suppression of glucagon in response to glucose, resulting in (c) a decreased insulin/glucagon molar ratio. These data support the suggestion that both alpha and beta cells of diabetic pancreases may be insensitive to glucose.

Sequence variations of the glucokinase gene in Japanese subjects with NIDDM.

Mutations in the glucokinase gene have been identified recently in patients with maturity-onset diabetes of the young, a subtype of NIDDM. The proposed role of glucokinase as a glucose sensor, combined with the low insulin response to glucose found in most Japanese with NIDDM, prompted us to speculate that mutations in the glucokinase gene might be one of the major causes of NIDDM in Japanese subjects. To determine the prevalence of mutations and sequence variations in the glucokinase gene, we screened all 12 exons of the glucokinase gene, including exon/intron junctions, by polymerase chain reaction followed by single-strand conformation polymorphism in 209 Japanese NIDDM subjects. In addition to the mutation in exon 7, which substituted Arg (AGG) for Gly (GGG) at codon 261 (10), a silent mutation of Pro (CCC-->CCG) in exon 4 at codon 145 and several new sequence variations in intervening sequences and the 5'-untranslated region of exon 1 beta (beta-cell-specific exon 1) were identified. Because we identified only one subject who had a structurally abnormal glucokinase molecule, we conclude that the prevalence of structural mutations in the glucokinase gene responsible for NIDDM appears to be rare among Japanese patients. To our knowledge, this is the first thorough study describing the ethnic prevalence of mutations and sequence variations in the glucokinase gene in NIDDM.

Evidence for association between the class I subset of the insulin gene minisatellite (IDDM2 locus) and IDDM in the Japanese population.

Although the shortest (class I) minisatellite (i.e., variable number of tandem repeats [VNTR]) alleles in the 5' region of the insulin gene are positively associated with IDDM in Caucasians, the majority of Japanese are homozygous for class I alleles. Here, we determined the exact length, in number of repeat units (RUs), of class I alleles in Japanese subjects. The distribution of class I alleles in Japanese was trimodal, with peaks located at 32/33, 41, and 44 RUs. The shortest component (i.e., 1S [25-38 RUs]) alleles were significantly increased in the IDDM group compared with the control group (54 vs. 46%; P = 0.040). The 1S/1S genotype was significantly increased in the IDDM patients (34 vs. 20%; P = 0.005; relative risk 2.1). Furthermore, the transmission disequilibrium test of Japanese families with 1S/1M or 1S/1L heterozygous parents confirmed the association of 1S alleles; 17 alleles of 1S and 6 alleles of 1M (39-41 RUs) or 1L (42-44 RUs) were transmitted to affected offspring (P = 0.022). In addition, we found tight linkage of 1S with allele 9 of the tyrosine hydroxylase gene microsatellite and allele (-) of the IGF-II gene Apa I polymorphism, but neither 9 nor (-) alleles were significantly associated with IDDM. The present study suggests that a class I subset may have a role in IDDM susceptibility in Japan. It was revealed that the difference between 1S alleles and 1M or 1L alleles is almost consistently characterized by a sequence variation generated by deletion of two copies of an ACAGGGGTCC CGGGG repeat element, implying that sequence variation of class I alleles may influence disease susceptibility.

Chlorpropamide-induced hyponatremia: incidence and risk factors.

The incidence and risk factors of chlorpropamide-induced hyponatremia were assessed in diabetic outpatients. In 176 chlorpropamide-treated patients, 11 (6.3%) exhibited hyponatremia (serum sodium less than or equal to 129 meq/L) during the mean follow-up period of 7.4 yr. In contrast, only one (0.6%) developed hyponatremia in 162 tolbutamide- or glibenclamide-treated patients (P less than 0.005). Moreover, administration to elderly patients and combination with thiazide diuretics were regarded as significantly potent risk factors for the development of hyponatremia in patients receiving chlorpropamide.

The high prevalence of the diabetic patients with a mutation in the mitochondrial gene in Japan.

Recently, an A to G transition at position 3243 in transfer ribonucleic acidLeu(UUR) [the 3243 base-pair (bp) mutation] originally found in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes has been identified in patients with diabetes and deafness. To determine the prevalence of the diabetic patients with this mutation in Japan, we screened 550 randomly selected cohorts of diabetic patients without prior information about clinical features such as type of diabetes, family history of diabetes, age of onset, and mode of therapy. We have identified 5 patients with this mutation, suggesting that approximately 0.9% of diabetic patients have the 3243 bp mutation. However, there were no subjects with this mutation in 250 controls with normal glucose tolerance. The percentage of mutant DNA in whole mitochondrial DNA did not correlate to the degree of symptoms. We conclude that the 3243 bp mutation in the mitochondrial gene plays an important part as a cause of diabetes in Japan.

Analysis of the glucokinase gene promoter in Japanese subjects with noninsulin-dependent diabetes mellitus.

Glucokinase plays an important role in glucose metabolism in pancreatic beta-cells and liver. Recently, several mutations responsible for noninsulin-dependent diabetes mellitus (NIDDM) have been identified within the coding regions of the glucokinase gene. We screened the promoter regions using polymerase chain reaction followed by single strand conformation polymorphisms in 240 Japanese NIDDM and 111 control subjects. In the beta-cell promoter, two kinds of sequence variations were detected. One variation, in which 2 nucleotides at position -282 (C-->T) plus -194 (A-->G) were changed simultaneously, was found in 23 NIDDM (9.6%) and 12 control (10.8%) subjects. The other variation [e.g. -30 (G-->A)] was identified in 87 NIDDM (36.3%) and 40 control (36.0%) subjects. In the liver promoter, in addition to the -603 (G-->T) substitution in 1 NIDDM (0.4%) and 2 control (1.8%) subjects, the -120 (G-->T) substitution in 1 control (0.9%) subject was found. However, there were no differences in these allele frequencies between NIDDM and control subjects. We conclude that the prevalence of mutations in the promoter of the glucokinase gene responsible for NIDDM is rare among Japanese patients.

Insulin secretory response in Japanese type 2 (non-insulin-dependent) diabetic patients.

Insulin (immunoreactive insulin, IRI) response during a 100 g oral glucose tolerance test was studied in a large number of patients with definite diabetes, equivocal diabetes, and other pathological states causing glucose intolerance. Definite diabetes was diagnosed in patients with overt fasting hyperglycemia. Once the diagnosis of definite diabetes was made, IRI response remained low after improvement of glucose tolerance. Glucose intolerance caused by other pathological extra-pancreatic conditions was usually accompanied by increased IRI response. IRI response in equivocal diabetes was variable, but almost always decreased in those who developed definite diabetes later. In subjects with a strong family history of type 2 diabetes, the prevalence of a low IRI response was high. In non-diabetic subjects, weight gain caused a marked increase in IRI response and a small increase in blood glucose, while in those who developed diabetes, IRI increased little despite the marked increase in blood glucose. These data suggest that low IRI response is an important feature of type 2 diabetes, perhaps with a hereditary basis in part. It precedes the occurrence of overt hyperglycemia and persists after improvement of glucose tolerance.

Risk factors for the development of diabetic retinopathy in Japanese type 2 diabetic patients.

This study investigated the risk factors for development of diabetic retinopathy (DR) in 787 type 2 diabetic patients with no retinopathy at the first visit. The subjects were followed up for at least 3 years (mean, 6.7 years). Among the baseline factors, significant correlations were observed between the development of DR and HbA1c (P < 0.0001), the method of therapy (P < 0.005), the duration of diabetes at the first visit (P < 0.005) and the past maximal body mass index (BMI) (P < 0.01). No significant correlation was found with the blood pressure, age, gender, TC or BMI. Among the follow-up variables, the mean HbA1c (P < 0.0001) and duration of diabetes (P < 0.001) correlated significantly with DR development, whereas the blood pressure and age did not. We found that a 1% decrease in HbA1c led to a 35% reduction in the risk of development of DR during the follow-up. The patients whose HbA1c at the first visit was higher than the median value of 8.2% showed a higher probability of development of DR during the next 3 years even when the same blood glucose control was maintained during the follow-up. In conclusion, our study demonstrated that the most important risk factor influencing the development of DR was the blood glucose control. Moreover, we found that the glycemic level at the first visit also influenced the development of DR.

Family history of diabetic patients in Japan.

The frequency of a positive family history of diabetes in diabetic patients has increased in recent studies. In this study, it was 16-33% for type 1 diabetes and 43-49% for type 2 diabetes. It was significantly higher than in non-diabetic subjects, and in type 2 than in type 1 diabetic patients. The prevalence of diabetes in parents and siblings of type 2 diabetic patients was higher than in those of type 1 patients, and it was particularly high in parents of young onset type 2 patients. Among type 2 diabetic patients, positive family history was somewhat lower in those with marked obesity in the past. Comparison of groups with varying degrees of glucose intolerance revealed that a family history of diabetes increased in parallel with the impairment of glucose tolerance. The results suggest that genetic factors in the pathogenesis of diabetes are more important in type 2 than in type 1 diabetes, and in the younger onset and less obese subjects than in older onset and more obese patients for type 2 diabetes.

Characteristics of cranial nerve palsies in diabetic patients.

The incidence of palsy in the third, sixth and seventh cranial nerves was studied with regard to central nervous system involvement in diabetic patients. Among 1961 diabetic patients, 19 (0.97%) demonstrated cranial nerve palsies. Nine out of these 19 patients showed facial palsy; 6 palsy of the oculomotor nerve; 2 palsy of the abducent nerve; and 3 both oculomotor and abducent nerve palsies. In contrast, only 5 out of 3841 non-diabetic patients (0.13%) had any cranial nerve palsies; all 5 were cases of facial palsy. The incidence of cranial palsies in diabetic patients was significantly higher than that in non-diabetic patients (P less than 0.01). Concerning age, sex, the state of glycemic control, diabetic complications and method of treatment, there were no differences disclosed in the diabetic patients with cranial nerve palsy. The incidences of diabetic complications were compared between the patients with facial palsy and those with ophthalmoplegia. Only one out of 9 patients with facial palsy (11%) had diabetic complications, whereas 7 out of 10 patients with ophthalmoplegia (70%) demonstrated diabetic complications and the difference was significant. Thus ophthalmoplegia appears to be more closely related to diabetic metabolism while facial palsy is less strongly correlated with diabetes.

Standardization of HbA1c value and its comparison to immunoassay--two years of experience.

In spite of the routine use of hemoglobin Alc (HbAlc) value to guide diabetes therapy, substantial differences have been noted between results obtained by different instruments and laboratories. It was suggested that confusion between the terms used for HbA1c, i.e. between "total HbA1c' which includes labile content, and "stable HbA1c', which does not, may account for some of these inter-instrument and inter-laboratory differences. However, an undesirable difference was found even in measurements of only the stable component of HbAlc using the two most commonly used HPLC analyzers in our country. We found that a two-point calibration using lyophilized hemoglobin at lower and higher ranges was effective in matching up results of HbA1c measurement. This finding was concordant with a report by the Committee of the Japan Diabetes Society and other reports. Two methods of HbA1c immunoassay, one performed with the DCA 2000 automated analyzer and another performed using the Liquitech kit or a general automated analyzer, were evaluated and found to perform as well as HPLC analyzers in all respects except precision. The results derived from immunoassay were in good agreement with the calibrated results by HPLC, with (Liquitech) and without (DCA 2000) conversions.

Serum gliclazide concentration in diabetic patients. Relationship between gliclazide dose and serum concentration.

Serum levels of gliclazide were determined by radioimmunoassay in seven healthy controls and in 18 diabetic in-patients receiving single oral dosing and consecutive dosing over 5 days. Following a single oral dose of 40 mg in the seven controls and eight diabetic patients, and 120 mg in ten diabetic patients, the serum levels of gliclazide peaked on average at 2 h, followed by a slow decline, the t1/2 being 16.5 h in the volunteers, 12.3 h in the diabetic patients receiving 40 mg, and 10.5 h in those receiving 120 mg. During consecutive administration, the serum levels both at fasting and at the peak reached a plateau in 2 days and no further accumulations were observed. The steady-state peak levels of gliclazide in the diabetic patients revealed a strongly positive correlation with the dose per m2 body surface area (r = 0.78, P less than 0.001), and their steady-state fasting levels correlated positively but weakly with the dose per m2 body surface area (r = 0.48, P less than 0.05). Thus, measuring either the fasting or the peak concentration of gliclazide will be useful for monitoring drug concentration in the serum. Pharmacokinetics of gliclazide will contribute to the elucidation of the relationship of serum level and clinical effectiveness in diabetic subjects.

[Computed tomographical evaluation of diabetic nephropathy].

Diabetic nephropathy can be regarded mainly as a type of microangiopathy, but is a disease that may also include aspects of macroangiopathy. This is especially true of renal disease in non-insulin dependent diabetes mellitus (NIDDM), which is characterized not only by diabetic glomerulosclerosis, but also by atherosclerosis. We performed morphological studies on the kidney, using computed tomography (CT), focusing on such points as: (1) abdominal aortic calcifications at the level of kidney, (2) calcifications in the renal artery, and (3) wedge-shaped defects on the renal surface. We noted that these findings became more prominent in NIDDM patients during end-stage renal failure than during normal renal function, and were significantly more common in those two NIDDM groups than in age-matched nondiabetic patients without hypertension, hyperlipidemia or gout. NIDDM patients exhibited these features more frequently than IDDM patients.