Gene expression profile in bone of diabetes-prone BB/OK rats fed a high-fat diet

A high-fat diet (HFD) has been recognized as a risk factor for diseases such as dyslipidemia, atherosclerosis, obesity, and osteoporosis. However, studies analyzing gene expression after HFD in bone are rare. That prompted us to analyze the expression of selected genes in bone of 4-week-old diabetes-prone B(io)B(reeding) rats. Two breeding pairs were fed a HFD (+10 % tallow) or were fed a normal diet (ND; Ssniff R-Z) before mating and afterward during pregnancy. After the birth of progeny, parents continued to be given HFD or ND until the progeny was weaned (3 weeks). Thereafter, offspring were weaned and were fed the same food as their parents up to an age of 4 weeks. Body weight was measured at an age of 4 weeks, and subsequently 13 HFD rats and 13 ND rats were killed and the tibial bone was harvested to analyze the expression of 53 genes in bone. All rats fed HFD were significantly heavier than rats fed ND after 3 and 4 weeks. The diet also influenced the expression of genes in bone. There were significant differences in 20 out of 53 genes studied between rats fed HFD compared with rats fed ND. Four out of 20 had a lower and 17 out of 20 genes a higher expression in HFD rats, but differences in gene expression showed obvious differences between males and females. There were only two genes that were similarly different between males and females: Bmp4 and Atf4. Two genes, Foxg1 and Npy, were inversely expressed in males and females. It seems that the gene expression is differently regulated by diet during pregnancy and later in life between males and females. Nevertheless, it cannot be excluded that HFD also acts as an epigenetic factor in the development of offspring in utero.     

Genes of SHR rats protect spontaneously diabetic BB/OK rats from diabetes: lessons from congenic BB.SHR rat strains

Diabetes in BB rats share many common features with human type 1 diabetes. One of them is the complex and polygenic nature of disease. Analysis of cross hybrids of diabetic BB/OK rats and rats of different diabetes-resistant strains has demonstrated that beside the MHC genes, Iddm1 and the lymphopenia, Iddm2, additional non-MHC genes are involved in diabetes development. To study the importance of the non-MHC genes, Iddm4 and Iddm3, two congenic BB.SHR rat strains were generated by recombining a segment of the SHR chromosome 6 (Iddm4; termed BB.6S; 15cM) or chromosome 18 (Iddm3; termed BB.18S; 24cM) into the BB/OK background by serial backcrossing and marker-aided selection. The characterization of both congenic strains demonstrates a drastic reduction of diabetes frequency in comparison to the BB/OK strain (86% vs 14% and 34%). It is supposed that diabetes protective genes of SHR must be located on both chromosomal segments and that these suppress the action of the essential and most important genes of diabetes development in the BB/OK rat, Iddm1, and Iddm2.     

Antiviral treatments reduce severity of diabetes in Ljungan virus-infected CD-1 mice and delay onset in diabetes-prone BB rats

The effects of LV in two different species, CD-1 mice, without a genetic disposition for diabetes, and BB rats prone to T1D were examined. Male CD-1 mice that had been exposed to LV in utero developed a type 2-like diabetes with increased blood glucose, insulin levels and epididymal fat at the age of 10–15 weeks. Combination therapy including LV-antiserum and an antiviral drug, Pleconaril, significantly reduced the levels of blood glucose and insulin and the amount of abdominal fat. In BB rats, LV has been found in both prediabetic- and diabetic diabetes-prone rats, as well as in diabetes-resistant rats. To evaluate whether the presence of LV has any influence on the onset of T1D, prediabetic BB rats were treated with an antiserum against LV or a combination of the antiviral drugs Pleconaril and Ribavirin. In the group treated with antiviral drugs, the onset was significantly delayed. These results indicate that the presence of LV can be involved in the pathogenesis of diabetes in these animal models.     

Absence of the RT-6 T cell subset in diabetes-prone BB/W rats

Diabetes-prone Bio-breeding/Worcester (DP) rats exhibit a severe T cell lymphopenia and autoimmune pancreatic insulitis. The present results indicate that the T cell lymphopenia is due in large part, if not entirely, to the absence of the RT-6+ peripheral T cell subset, which includes members of both the helper/inducer (W3/25) and suppressor/cytotoxic (OX 8) antigenic phenotypes. Delineation of the causal mechanism(s) for the selective absence of RT-6+ T cells in DP rats may provide important insights into the cellular basis of the insulin-dependent diabetes mellitus syndrome in these animals.     

Adoptive transfer of autoimmune diabetes mellitus in biobreeding/Worcester (BB/W) inbred and hybrid rats

Adoptive transfer of diabetes was accomplished by the injection of Con A-activated acutely diabetic BB/W rat spleen cells into immunosuppressed diabetes-resistant BB/W control rats and F1 hybrid offspring produced by BB/W X Lewis, BN, Yashida, and NEDH matings. Immune suppression methods that facilitated adoptive transfer of diabetes included neonatal thymectomy, cyclophosphamide, and splenectomy plus rabbit anti-rat lymphocyte serum injections. The successful transfer of BB/W diabetes to otherwise normal (BB/W X inbred)F1 rats and to diabetes-resistant BB/W animals suggests that antigenically normal pancreatic beta cells were destroyed by the injected effector cells. Diabetes-resistant BB/W control rats also evidenced diabetes after the injection of cyclophosphamide alone. The requirement for immunosuppression suggests that an intact immune system protects against adoptive transfer and diabetes in diabetes-resistant BB/W rats.     

Fetal thymi from diabetes-prone but not diabetes-resistant BB/Wor rats fail to generate mature ART2+ T-cells in organ culture.

Diabetes-prone (BBDP) BB rats develop spontaneous autoimmune diabetes mellitus. They are lymphopenic and severely deficient in ART2+ T-cells. Diabetes-resistant BB (BBDR) rats do not develop spontaneous diabetes and have normal numbers of ART2+ T-cells. T-cell lymphopenia in BBDP rats results from hematopoietic stem cell defects leading to abnormal intrathymic T-cell maturation. To study this process, we established rat fetal thymic organ cultures (FTOC). Like mouse FTOC, cultures of BBDR rat thymi yielded approximately 10(5) cells per lobe. The majority of cells were CD8+ART2+ T-cells. In contrast, BBDP rat FTOC yielded 60% fewer cells (approximately 0.3 x 10(5)/lobe), a smaller percentage of CD8+ and TcRalphabeta+ T-cells, and almost no detectable ART2+ T-cells. ART2 mRNA was detectable in BBDR but not BBDP FTOC. In contrast, expression of mRNAs encoding bcl-2 and a panel of cytokines was comparable in BBDP and BBDR FTOC. Addition of anti-ICAM-1 (CD54) antibody reduced T-cell number in BBDR rat FTOC by approximately 70%, but addition of IL-7 or IL-1beta had no effect. The data demonstrate that BBDP thymocytes fail to generate mature ART2+ T-cells in rat FTOC, a system that can now be used to study the mechanism of this process.     

Modifications in platelet membrane transport functions in insulin-dependent diabetes mellitus and in gestational diabetes.

The pathogenesis of plasma membrane alterations present in diabetes mellitus is unclear. To add new insights to the question, platelet membrane properties were evaluated in 16 women presenting impaired glucose tolerance at the 28-29th week of gestation (GDM) and in 8 women with insulin-dependent diabetes mellitus (IDDM). 15 healthy pregnant women (HPW) and 21 healthy non-pregnant (HNPW) women were the control group for GDM and IDDM, respectively. Pregnancy (HPW vs. HNPW) provoked an increase in Ca(2+)-ATPase activity and a decrease in membrane fluidity; in contrast, Na+/K(+)-ATPase, intracellular free Ca2+ concentrations, membrane cholesterol and phospholipid content did not vary. Both GDM and IDDM showed lower Na+/K(+)-ATPase activity and higher Ca2+ concentration, compared to HPW and HNPW, respectively, whereas Ca(2+)-ATPase activity was higher only in IDDM; furthermore, membrane fluidity was lower in GDM and higher in IDDM. Finally, GDM showed higher membrane cholesterol content. Both GDM and IDDM showed a very good metabolic control so that variations reported cannot be due to hyperglycemia; it is tempting to suggest that membrane variations are present before the clinical metabolic alteration. Furthermore, both GDM and IDDM were on insulin therapy, therefore: (i) insulin may be the pathogenetic factor of higher intracellular free Ca2+ concentrations and lower Na+/K(+)-ATPase activity since they both varied accordingly in GDM and IDDM, but not of (ii) changes in Ca(2+)-ATPase, membrane fluidity and cholesterol content which did not vary accordingly in GDM and IDDM.     

A combined segregation and linkage analysis of insulin-dependent diabetes mellitus.

In an effort to clarify the mode of inheritance of insulin-dependent diabetes mellitus (IDDM), a total of 230 nuclear families with pointers were analyzed using the computer program COMBIN. Each family was ascertained without deliberate selection for multiplex families, and most families were completely typed for HLA-B, HLA-DR, and properdin factor B (Bf). There were 186 families with normal parents, 44 families with one affected parent, and no families with two affected parents. The computer program COMBIN evaluates evidence for a major locus of disease susceptibility, linkage of the major locus to a known genetic marker locus, linkage disequilibrium between the marker haplotypes and disease susceptibility, pleiotropic effects, and presence of an unlinked modifier. The parameters of COMBIN are T, Q, and D, representing the displacement, gene frequency of the IDDM allele, and dominance, respectively, of the major locus--and TM, QM, and DM being the analogous parameters of the modifier. In addition, the recombination fraction, theta, between the IDDM locus and HLA as well as the coupling frequencies are estimated. Finally, COMBIN simultaneously performs segregation and linkage analysis, with the optimal model being adjusted by the fit to the haplotype sharing distribution of IDDM. The results of these analyses indicated that the best-fitting genetic model of diabetic susceptibility appears to be a single major locus with near recessivity on a scale of standardized genetic liability, with gene frequency of the IDDM susceptibility allele of approximately 14%. In addition, the recombination fraction between the major locus and HLA is zero in all models; that is, for the B-BF-DR haplotype, the IDDM locus is tightly linked, probably (according to data from previous studies) to HLA-DR. Information determined by magnitude of coupling frequencies indicated that there is significant positive linkage disequilibrium with the haplotypes B8-BfS-DR4 and B15-BfS-DR4, significant negative linkage disequilibrium with B7-BfS-DR2, and intermediate disequilibrium for B8-BfS-DR3, B18-BfF1-DR3, and B40-BfS-DR4. Significant evidence in favor of an unlinked (to HLA) modifier (either single major locus or polygenes) could not be demonstrated. In conclusion, genetic susceptibility to IDDM appears to be most consistent with a single major locus with near recessivity that is tightly linked to HLA.     

Enhanced 2-deoxy-D-glucose uptake and metabolism in splenocytes from diabetic and diabetes-prone BB rats. Further evidence to support prior in vivo activation

Glucose metabolism in splenocytes from the BB rat was studied for the presence of abnormalities in [14C] 2-deoxy-D-glucose (2-dGlc) uptake, [U-14C]glucose conversion to 14CO2, and the production of lactate and pyruvate. Cells were studied freshly isolated ("resting"), and following culture both unstimulated (control) and stimulated with concanavalin A (ConA) or phorbol myristate acetate (PMA) + ionomycin. Both resting and control cells from diabetic (BBd) and diabetes-prone (BBdp) rats transported more (p less than 0.05) 2-dGlc than did cells from nondiabetes-prone (BBn) rats. Consistent with prior in vivo activation, sustained in vitro, lactate production was higher (p less than 0.05) under control conditions in BBd and BBdp than in BBn cells. Lactate production increased less with ConA and PMA + ionomycin in both BBd and BBdp than in BBn cells. PMA + ionomycin increased 2-dGlc uptake as much in BBd and BBdp cells as in BBn cells. Elevated rates of pyruvate production were observed in BBd cells under resting, control, and (especially) ConA conditions, suggesting an abnormality in pyruvate conversion to lactate. Few changes were observed in 14CO2 production. The presence of similar abnormalities in BBdp cells to those of the BBd cells suggests that the diabetic state is not causal, and the absence of an in vitro effect of 15 mmol/liter glucose in BBn cells further tends to exclude hyperglycemia as a cause of these alterations.     

Genetic markers and insulin-dependent diabetes mellitus (IDDM) in Sardinia.

The distributions of some genetic markers in 106 Sardinian individuals with insulin-dependent diabetes mellitus (IDDM) and in a control sample of 186 nondiabetic Sardinians were studied. A strong association of IDDM with some phenotypes of ACP, PGM1, C3 and GC genetic markers was found. In the IDDM patients there is a significant increase of ACP B, ACP B-C, PGM1 1S-1F and GC 1S-2 phenotypes. Particularly the individuals with the ACP B, PGM1 1S-1F and GC 1S-2 phenotypes show the highest values of the relative risk (RR) and the attributable risk (AR) and seem to be more susceptible to IDDM disease.     

Loci of the immune system are implicated in diabetes frequency and age at onset of diabetes in BB rats

The spontaneously diabetic BB rat is a well-established animal model in diabetes research developing an insulin-dependent type-1 diabetes mellitus closely resembling human diabetes. By several crossing studies using BB/OK rats it has been demonstrated that beside the MHC class-II genes of the RT1^u haplotype, Iddm1, and the lymphopenia, Iddm2, at least two additional non-MHC genes located on chromosomes 6 (Iddm4) and 18 (Iddm3) are involved in diabetes development. In addition, there are at least three genes located on chromosomes 6 (Dm1), 8 (Dm2) and 10 (Dm3) influencing the age at onset of diabetes. Comparing the homologous regions between rat and human, it is shown that most diabetogenic genes lie on human chromosomes near genes involved in immune processes providing human geneticist with new candidate regions for the analysis of diabetogenic non-MHC genes in human type-1 diabetes.     

Human sciatic nerve phospholipid profiles from non-diabetes mellitus,non-insulin-dependent diabetes mellitus and insulin-dependent diabetes mellitus individuals. A 31P NMR spectroscopy study

• 1.1. Human sciatic nerve phospholipids obtained from non-diabetes mellitus (NDM), non-insulin-dependent diabetes mellitus (NIDDM), and insulin-dependent diabetes mellitus (IDDM) patients, after lower extremity amputation, were studied by ³¹P NMR spectrometry.
• 2.2. Nine phospholipids resonances in NDM and NIDDM groups were identified as followed: Ethanolamine plasmalogen (Epias, Chemical shift = 0.07δ); phosphatidylethanolamine (PE, 0.03δ); phosphatidylserine (PS, −0.05δ); sphingomyelin (SM, −0.09δ); lysophosphatidylcholine (LPC, −0.28δ); phosphatidylinositol (PI, −0.30δ); alkylacylphosphorylcholine (A1.PC, -0.78δ); phosphatidylcholine (PC −0.84δ), and an unknown resonance (U, 0.13δ).
• 3.3. In the IDDM group a resonance of lysophosphatidylinositol (LPI, 0.01δ) was detected in addition to the nine phospholipids listed above.
• 4.4. IDDM showed that PI and Al.PC were elevated and U was lower when compared with NDM; also, Eplas was lower when compared with NIDDM. PC was elevated and PS was lower when compared with both NDM and NIDDM.
• 5.5. Indices calculated from this data, showed that the choline ratio and choline/ ethanolamine ratio were elevated; while ethanolamine ratio, and myelin ratio were lower in IDDM group, when compared with both NDM and NIDDM groups.
• 6.6. Inactivation of the cholineacethyltransferase enzyme (ChAT) and enhancement of the phospholipidmethyltransferase enzyme (PLMT), secondary to an insulin deficiency, are proposed as an interpretation of these findings.

     

Plasmapheresis in the initial treatment of insulin-dependent diabetes mellitus in children.

Several factors indicate that autoimmune mechanisms may play a part in the aetiology of insulin-dependent diabetes mellitus. At the onset of the disease in 10 children (aged 11-16 years) plasmapheresis was performed four times over one to two weeks. Seventeen age-matched children with the same clinical features served as controls. The C-peptide concentrations at onset were the same in the two groups, but after one month the children treated with plasmapheresis had significantly higher values. This difference became even more pronounced after three, nine, and 18 months, both during fasting and at the maximum response to a standardised meal. The study group also had a significantly more stable metabolism, longer partial remission, and no higher insulin requirement. Of the 10 treated children islet-cell cytoplasmic antibodies were present in seven before plasmapheresis and in nine during treatment. The antibodies remained detectable in five and six out of nine patients at one and six months respectively after plasmapheresis. Although the mechanisms are obscure, plasmapheresis performed at the onset of insulin-dependent diabetes mellitus may help to preserve beta-cell function.     

Effect of alpha-phenyl-N-tert-butylnitrone on diabetes and lipid peroxidation in BB rats.

Oxygen free radicals have been shown to interfere with pancreatic islet beta cell function and integrity, and have been implicated in autoimmune type 1 diabetes. We hypothesized that the spontaneous autoimmune type 1 diabetes of the BB rat would be prevented by in vivo administration of a free-radical spin trap, alpha-phenyl-N-tert-butylnitrone (PBN). Twenty-eight diabetes-prone (BBdp) and 13 non-diabetes-prone (BBn) rats received PBN (10 mg/kg) subcutaneously twice daily, and 27 BBdp and 12 BBn rats received saline as controls. Rats were treated from age 47 +/- 6 days until diabetes onset or age 118 +/- 7 days. PBN caused no growth, biochemical, or hematological side effects. Sixteen control BBdp rats became diabetic (BBd, mean age 77 +/- 6 days) and six demonstrated impaired glucose tolerance (IGT rats). The incidence of diabetes and IGT was not different in PBN-treated BBdp rats. Saline-treated rats showed no differences in pancreatic malondialdehyde (MDA) contents of BBd, IGT rats, and the BBdp that did not develop diabetes, versus BBn rats (2.38 +/- 0.35 nmoL/g). Among rats receiving PBN, BBn had lower pancreatic MDA than BBd and IGT rats (1.38 +/- 0.15 vs. 1.88 +/- 0.15 and 2.02 +/- 0.24 nmoL/g, p < 0.05), but not than BBdp rats (1.78 +/- 0.12 nmoL/g, ns). BBn rats receiving PBN also had lower pancreatic MDA than the saline controls (p < 0.05). Thus, PBN is remarkably nontoxic and is able to decrease MDA in the absence of the autoimmune process, but does not prevent diabetes. A combination of PBN with other complementary antioxidant agents may hold better promise for disease prevention.     

Heterogeneity of non-insulin-dependent diabetes mellitus in HLA types and clinical features: comparison with insulin-dependent diabetes mellitus

We determined HLA types in 110 Japanese patients with non-insulin-dependent diabetes mellitus (NIDDM) and studied the relationship between the HLA phenotypes and clinical features. Sixty-nine patients with insulin-dependent diabetes mellitus (IDDM) and 100 healthy blood donors served as controls. Concerning HLA DR and DQ loci, frequencies of DR4, DRw9 and DQw3.2 were higher, and those of DR2, DRw8, DRw11, DRw12 and DQw1 were lower in patients with IDDM compared than in healthy controls. There were no differences between NIDDM and normal controls in the frequency of a particular HLA DR antigen except for a decreased frequency in DRw11 in the former. The frequency of DQw3.2 antigen in NIDDM was intermediate between IDDM and normal controls. There were some differences between DQw3.2-positive and -negative NIDDM patients in clinical features. Those who showed low C-peptide responses during oral glucose tolerance test were more frequently found among DQw3.2-positive NIDDM patients. These results suggest that Type 1 diabetes mellitus may have a mild clinical course and is found among the Japanese NIDDM population.     

High frequency of HLA-DQB1 non-Asp(57) alleles in Kuwaiti children with insulin-dependent diabetes mellitus

The prevalence of polymorphic amino acids at position 57 of the HLA DQB1 in Kuwaiti children with insulin-dependent diabetes mellitus (IDDM) and nondiabetic controls has been determined using a polymerase chain reaction-sequence-specific primers (PCR-SSP) method. Using this approach, 34/55 (62%) IDDM children were found to be homozygous Ala/Ala and 19/55 (35%) were heterozygous with various combinations. Amongst the IDDM children with heterozygous genotype at codon 57 of HLA DQB1, 6/55 (11%) had Asp/Ala, 8/55 (15%) had Ala/Val, 4/55 (7%) had Ala/Ser and 1/55 had Asp/Val allelic combinations. When considered collectively, the nonaspartate (NA) alleles were represented in 87% of the IDDM cases and only 13% cases had Asp(57) allele in different heterozygous combinations, while none of the IDDM subjects had a homozygous Asp genotype. In nondiabetic controls, homozygous non-Asp (NA) alleles were represented in 44% subjects, 37% of the controls were heterozygous (NA/A) and 19% had a homozygous (A/A) genotype. These differences between the IDDM group and the control group were found to be statistically significant. Our data report one of the highest frequency of NA/NA residues at this locus compared with that from different world populations (Sardinians, Norwegians, US Caucasians, US Blacks and Chinese).     

Free radical activity during development of insulin-dependent diabetes mellitus in the rat.

Free radical-induced lipid peroxidation was quantified by measuring expired pentane from diabetic prone BB Wistar rats of 45-90 d of age. Insulin-dependent diabetes mellitus was manifest at the age of 71 +/- 8 d. Expired pentane increased from 2.1 +/- 0.7 to 5.0 +/- 3.0 pmol/100g/min (p less than 0.01) at manifestation of the disease and remained high throughout the test period. In healthy age-matched control rats it persisted low. In rats made diabetic with streptozotocin, expired pentane remained low. The changes in expired pentane suggest that the development of endogenous insulin-dependent diabetes mellitus in BB rats is associated with increased free radical activity. This is not due to hyperglycemia or ketosis per se, and reflects a fundamental difference in the free radical activity between the spontaneously diabetic BB rats and the disease produced by streptozotocin. Development of spontaneous insulin-dependent diabetes in BB rats is associated with increased free radical activity that persists after the manifestation of the disease.     

Regulation of ANP secretion in insulin-dependent diabetes mellitus and the influence of autonomic neuropathy.

In order to determine the effect of diabetic autonomic neuropathy (DAN) on the atrial natriuretic peptide (ANP) response to dynamic stimuli, we studied the ANP response to 60 degrees head-up and 60 degrees leg-up tilt in diabetic subjects with (DAN + ve, n = 8) and without (DAN - ve, n = 8) evidence of autonomic neuropathy and seven matched non-diabetic controls. Mean baseline plasma ANP concentrations were similar in all three groups. Head-up tilt was associated with a fall in plasma ANP in all seven healthy controls (21.8 (16.8-30.7) to 16.8 (7.1-29.1), P = 0.06, mean (range)), seven of the eight DAN - ve (16.9 (6.5-33.7) to 8.5 (3.0-21.1), P = 0.015) and all eight DAN + ve subjects (27.3 (8.5-101.5) to 15.4 (1.0-67.6), P = 0.044). Leg-up tilt caused a rise in plasma ANP in six of the seven healthy controls (17.6 (7.5-27.9) to 22.4 (15.2-48.1), P = 0.041), six of the eight DAN - ve (12.5 (7.8-27.8) to 15.5 (7.3-31.3), P = 0.054) and seven of the eight DAN + ve subjects (18.2 (2.8-55.1) to 25.1 (4.5-92.8), P = 0.013). There was no significant difference in the fall in plasma ANP during head-up tilt or in the rise in plasma ANP during leg-up tilt between the three groups. We conclude that the regulation of ANP secretion is normal in diabetes mellitus, and is unaffected by the presence of autonomic neuropathy.     

Investigation of the mode of inheritance of insulin-dependent diabetes mellitus in Japanese subjects.

Previous studies have shown that insulin-dependent diabetes mellitus is positively associated with HLA-DR4 and HLA-DR9 in Japanese populations. It was proposed that susceptibility to the disease is determined by a single HLA allele associated with both DR4 and DR9. DR genotypes in a Japanese population with insulin-dependent diabetes mellitus were determined by DRB/DQB RFLP analysis. A single disease-susceptibility-allele model was tested by the antigen-genotype-frequency-among-patients method. Recessive and additive inheritance of a single susceptibility allele were rejected. The DR9-associated disease-susceptibility allele in Japanese subjects is distinct from both the DR3- and DR4-associated susceptibility alleles in white Caucasians. The data suggest further complexity in the inheritance of HLA-associated susceptibility to insulin-dependent diabetes mellitus.     

The diabetes-prone NZO/Hl strain. Proliferation capacity of beta cells in hyperinsulinemia and hyperglycemia

New Zealand Obese (NZO) male mice develop a polygenic juvenile-onset obesity and maturity onset hyperinsulinemia. Approximately 50% transit to chronic hyperglycemia. Here we report on the proliferation of beta cells in relation to both the individual's metabolic status and structural parameters of the endocrine pancreas. Proliferating beta cells were quantified in pancreas sections by immunoenzymatic double staining of Ki-67 protein, as a marker for proliferating cells, and endocrine non-beta cells in order to distinguish them from beta cells. In normoglycemic NZO/Hl males Ki-67 labelling indices (IKi-67) of beta cells varied between 0.14 and 1.5%, and correlated significantly with both serum insulin levels and beta cell size. There was no correlation with the glycemic status. In diabetic males, beta cell size was increased. IKi-67 varied between 1 and 3%. The data suggest that the secretory activity of beta cells triggered by glucose, entailed changes in both beta cell hypertrophy and proliferation. As shown by morphometric measurements, beta cell expansion in diabetic mice was limited, in spite of high IKi-67 values. This suggested increased death rates of beta cells.