A missense mutation in the hepatocyte nuclear factor 4 alpha gene in a UK pedigree with maturity-onset diabetes of the young

Summary Maturity-onset diabetes of the young (MODY) is a monogenic subgroup of non-insulin dependent diabetes mellitus (NIDDM) characterised by an early age of onset (< 25 years) and an autosomal dominant mode of inheritance. MODY is genetically heterogeneous with three different genes identified to date; hepatocyte nuclear factor 4 alpha (HNF-4α) [MODY1], glucokinase [MODY2] and hepatocyte nuclear factor 1 alpha (HNF-1α) [MODY3]. A nonsense mutation in the HNF-4α gene has recently been shown to cause MODY in a single large North American pedigree (RW). We screened a large UK Caucasian MODY family which showed weak evidence of linkage to the MODY1 locus on chromosome 20q (lod score for ADA 0.68 at θ = 0) for mutations in the coding region of the HNF-4α gene by direct sequencing. A missense mutation resulting in the substitution of glutamine for glutamic acid was identified in exon 7 (E276Q). The mutation was present in all of the diabetic members of the pedigree plus two unaffected subjects and was not detected in 75 normal control subjects or 95 UK Caucasian subjects with late-onset NIDDM. This is the first missense mutation to be described in the HNF-4α gene. [Diabetologia (1997) 40: 859–862] Received: 7 March 1997 and in revised form: 16 April 1997     

High frequency of mutations in MODY and mitochondrial genes in Scandinavian patients with familial early-onset diabetes

Abstract Aims/hypothesis. To investigate the contribution of mutations in maturity-onset diabetes of the young (MODY) and mitochondrial genes to early-onset diabetes with a strong family history of diabetes in a cohort with a high prevalence of Type I (insulin-dependent) diabetes mellitus. Methods. Screening for sequence variants in the hepatocyte nuclear factor (HNF)–4 α (MODY1), glucokinase (MODY2), HNF-1 α (MODY3) genes and mitochondrial DNA was carried out in 115 Finnish and Swedish patients with early-onset ( ≤ 40 years) diabetes using the single strand conformation polymorphism (SSCP) technique and direct sequencing. Allele frequencies were compared with 118 patients with onset of diabetes Type II (non-insulin-dependent) diabetes mellitus after the age of 40 and 92 non–diabetic control subjects without a family history of diabetes. Results. In total 52 sequence variants were found in the HNF-1α, HNF-4α and glucokinase genes, 12 of which were considered as MODY mutations. Three families had the A3243G mutation in the mitochondrial tRNA ^Leu gene, which resulted in an overall prevalence of these mutations of 13 %. Conclusion/interpretation. Among 115 Scandinavian families, mutations in the HNF-1α gene represented the most common cause of familial early-onset ( ≤ 40 years) diabetes: MODY3 (5.2 %) more than MODY2 (3.5 %) more than MIDD (2.6 %) more than MODY1 (1.7 %). [Diabetologia (1999) 42: 1131–1137] Received: 3 March 1999 and in revised form: 14 May 1999     

Plasma homocysteine is related to albumin excretion rate in patients with diabetes mellitus: a new link between diabetic nephropathy and cardiovascular disease?

Summary The high risk of cardiovascular disease in patients with diabetes mellitus, particularly in those with nephropathy, is not completely explained by classical risk factors. A high plasma homocysteine concentration is an independent risk factor for cardiovascular disease but information on its association with diabetes is limited. Fasting homocysteine concentrations were measured in the plasma of 165 diabetic patients (75 with insulin-dependent [IDDM]; 90 with non-insulin-dependent diabetes [NIDDM]) and 56 non-diabetic control subjects. Other measurements included the prevalence of diabetic complications, glycaemic control, lipid and lipoprotein levels, vitamin status and renal function tests. Patients with NIDDM had higher homocysteine levels than control subjects, whereas IDDM patients did not (9.2 ± 4.5 vs 7.7 ± 2 μmol/l, p < 0.01; and 7.0 ± 3 vs 7.4 ± 2 μmol/l, NS). Univariate correlations and multiple regression analysis showed albumin excretion rate to be the parameter with the strongest independent association with homocysteine. Patients with both types of diabetes and nephropathy had higher plasma homocysteine concentrations than those without nephropathy. Increases of homocysteine in plasma were related to increases in the severity of the nephropathy. Fasting hyperhomocysteinaemia was considered as the mean of the plasma homocysteine for all control subjects (7.5 ± 2.1 μmol/l) + 2 SD (cut-off =11.7 μmol/l). Nephropathy was present in 80 % of diabetic patients with fasting hyperhomocysteinaemia. In conclusion, increases in fasting homocysteine in diabetic patients are associated with increased albumin excretion rate, especially in those with NIDDM, thus providing a potential new link between microalbuminuria, diabetic nephropathy and cardiovascular disease. [Diabetologia (1998) 41: 684–693] Received: 4 August 1997 and in final revised form: 4 February 1998     

Insulin secretion and insulin sensitivity in diabetic subgroups: studies in the prediabetic and diabetic state

Aims/hypothesis. To evaluate insulin sensitivity and insulin secretion in prediabetic and diabetic subjects with mutations in MODY1 (HNF-4α) and MODY3 (HNF-1α) genes, in subjects with GAD antibodies, latent autoimmune diabetes in adults and in subjects with the common form of Type II (non-insulin-dependent) diabetes mellitus. Methods. Insulin secretion was measured as the incremental 30-min insulin (I30) and insulin glucose ratio (I:G30) during OGTT whereas insulin sensitivity was measured as the insulin sensitivity index during OGTT in 131 carriers of MODY mutations [NGT = 38, IFG/IGT = 21, diabetes mellitus (DM) = 72], in 293 subjects with GADA (NGT = 47, IFG/IGT = 29, DM = 217) and in 2961 subjects with a family history of the common form of Type II diabetes but without MODY mutations or GADA (NGT = 1360, IFG/IGT = 857, DM = 744). A subgroup of the subjects underwent a euglycaemic clamp (n = 210) and intravenous glucose tolerance test (n = 337) for the estimation of insulin sensitivity and first-phase insulin secretion. Results. Non-diabetic subjects with MODY mutations had pronounced impaired insulin secretion (I30, I:G30) compared with the two other groups (p = 0.005). Normal or non-diabetic glucose tolerance was maintained by enhanced insulin sensitivity compared with the other two groups (p < 0.05 and p < 0.005). In contrast to patients with Type II diabetes and with adult latent autoimmune diabetes, MODY patients showed only a modest deterioration in insulin sensitivity at onset of diabetes. The 2-h glucose values inversely correlated with insulin sensitivity in subjects with GADA (r = –0.447, p < 0.001) and subjects from Type II diabetic families (r = –0.426, p < 0.001), whereas no such relation was observed in subjects with MODY mutations (r = 0.151, p = NS). There were no statistically significant differences in insulin secretion or insulin sensitivity between subjects with GADA or subjects with a family history of Type II diabetes, either at the NGT or the IFG/IGT stage. Conclusion/interpretation. Glucose-tolerant carriers of MODY mutations are characterised by a severe impairment in insulin secretion. Enhanced insulin sensitivity is the most likely explanation for the normal glucose tolerance. Whereas subjects with positive GADA or Type II diabetes have impaired insulin sensitivity with increasing glucose concentrations, MODY mutation carriers seem to be protected from the effect of glucose toxicity. [Diabetologia (2000) 43: 1476–1483] Received: 23 March 2000 and in revised form: 29 August 2000     

Mutation screening in 18 Caucasian families suggest the existence of other MODY genes

Summary Maturity-onset diabetes of the young (MODY) is a heterogeneous subtype of non-insulin-dependent diabetes mellitus characterised by early onset, autosomal dominant inheritance and a primary defect in insulin secretion. To date five MODY genes have been identified: hepatocyte nuclear factor-4 alpha (HNF-4 α/MODY1/TCF14) on chromosome 20 q, glucokinase (GCK/MODY2) on chromosome 7 p, hepatocyte nuclear factor-1 alpha (HNF-1 α/MODY3/TCF1) on chromosome 12 q, insulin promoter factor-1 (IPF1/MODY4) on chromosome 13 q and hepatocyte nuclear factor-1 beta (HNF-1 β/MODY5/TCF2) on chromosome 17cen-q. We have screened the HNF-4 α, HNF-1 α and HNF-1 β genes in members of 18 MODY kindreds who tested negative for glucokinase mutations. Five missense (G31D, R159W, A161T, R200W, R271W), one substitution at the splice donor site of intron 5 (IVS5nt + 2T→A) and one deletion mutation (P379fsdelT) were found in the HNF-1 α gene, but no MODY-associated mutations were found in the HNF-4 α and HNF-1 β genes. Of 67 French MODY families that we have now studied, 42 (63 %) have mutations in the glucokinase gene, 14 (21 %) have mutations in the HNF-1 α gene, and 11 (16 %) have no mutations in the HNF-4 α, IPF1 and HNF-1 β genes. Eleven families do not have mutations in the five known MODY genes suggesting that there is at least one additionnal locus that can cause MODY. [Diabetologia (1998) 41: 1017–1023] Received: 5 January 1998 and in revised form: 8 April 1998     

Overexpression of dominant negative mutant hepatocyte nuclear factor (HNF)-1α inhibits arginine-induced insulin secretion in MIN6 cells

Aims/hypothesis. To explain the mechanisms whereby mutations in the HNF-1α gene cause insulin secretory defects. Methods. A truncated mutant HNF-1α (HNF-1α288 t) was overexpressed in hepatoma cells (HepG2) and murine insulinoma cells (MIN6) using a recombinant adenovirus system and expression of the HNF-1α target genes and insulin secretion were examined. Results. Expression of phenylalanine hydroxylase and α1-antitrypsin genes, the target genes of HNF-1α, was suppressed in HepG2 cells by overexpression of HNF-1α288 t. In MIN6 cells, overexpression of HNF-1α288 t did not change insulin secretion stimulated by glucose (5 mmol/l and 25 mmol/l) or leucine (20 mmol/l). Potentiation of insulin secretion by arginine (20 mmol/l, in the presence of 5 mmol/l or 25 mmol/l glucose) was, however, reduced (p < 0.0001 and p = 0.027, respectively). Similarly reduced responses were observed when stimulated with homoarginine. Expression of the cationic amino acid transporter-2 was not reduced and insulin secretory response to membrane depolarization by 50 mmol/l KCl was intact. Conclusion/interpretation. The HNF-1α288 t, which is structurally similar to the mutant HNF-1α expressed from the common MODY3 allele, P291fsinsC, exerts a dominant negative effect. Suppression of HNF-1α in MIN6 cells severely impaired potentiation of insulin secretion by arginine, whereas glucose-stimulated and leucine-stimulated insulin secretion was intact. Our findings delineate the complex nature of beta-cell failure in patients with MODY3. This cell model will be useful for further investigation of the mechanism of insulin secretory defects in these patients. [Diabetologia (1999) 42: 887–891] Received: 30 November 1998 and in revised form: 16 February 1999     

The genetic abnormality in the beta cell determines the response to an oral glucose load

Aims/hypothesis: We assessed how the role of genes genetic causation in causing maturity-onset diabetes of the young (MODY) alters the response to an oral glucose tolerance test (OGTT). Methods: We studied OGTT in 362 MODY subjects, from seven European centres; 245 had glucokinase gene mutations and 117 had Hepatocyte Nuclear Factor –1 alpha (HNF-1α) gene mutations. Results: BMI and age were similar in the genetically defined groups. Fasting plasma glucose (FPG) was less than 5.5 mmol/l in 2 % glucokinase subjects and 46 % HNF-1 α subjects (p < 0.0001). Glucokinase subjects had a higher FPG than HNF-1 α subjects ([means ± SD] 6.8 ± 0.8 vs 6.0 ± 1.9 mmol/l, p < 0.0001), a lower 2-h value (8.9 ± 2.3 vs 11.2 ± 5.2 mmol/l, p < 0.0001) and a lower OGTT increment (2-h – fasting) (2.1 ± 2.3 vs 5.2 ± 3.9 mmol/l, p < 0.0001). The relative proportions classified as diabetic depended on whether fasting (38 % vs 22 %, glucokinase vs HNF-1 α) or 2-h values (19 % vs 44 %) were used. Fasting and 2-h glucose values were not correlated in the glucokinase subjects (r = –0.047, p = 0.65) but were strongly correlated in HNF-1 α subjects (r = 0.8, p < 0.001). Insulin concentrations were higher in the glucokinase subjects throughout the OGTT. Conclusion/interpretation: The genetic cause of the beta-cell defect results in clear differences in both the fasting glucose and the response to an oral glucose load and this can help diagnostic genetic testing in MODY. OGTT results reflect not only the degree of hyperglycaemia but also the underlying cause. [Diabetologia (2002) 45: 427–435] Received: 13 September 2001 and in revised form: 26 November 2001     

Studies of the genetic variability of the coding region of the hepatocyte nuclear factor-4α in Caucasians with maturity onset NIDDM

Summary Mutations in the hepatocyte nuclear factor-4α (HNF-4α) gene cause the type 1 form of maturity onset diabetes of the young (MODY1). To address the question of whether genetic variability of HNF-4α is associated with late onset non-insulin-dependent diabetes mellitus (NIDDM) we have sequenced the coding region and intron/exon boundaries of the gene in 36 randomly recruited Danish NIDDM patients. Two nucleotide substitutions that changed the sequence of HNF-4α were identified: Thr/Ile130, which has been reported previously and a novel Val/Met255. The Val/Met 255 mutation was found in 4 of 477 Danish NIDDM patients and in none of 217 glucose tolerant control subjects; thus it cannot be excluded that this mutation may have an impact on NIDDM susceptibility. Among 509 NIDDM patients the allelic frequency of the Thr/Ile130 variant was 4.7 % (95 % confidence interval: 3.4–6.0 %) compared to 1.9 % (0.7–3.1 %) among 239 control subjects (p = 0.008). However, in a population sample of 942 Swedish men with an average age of 70 years the allelic frequency of the variant was similar in 246 men with either impaired glucose tolerance (5.6 % [2.6–8.6 %]) or NIDDM (5.4 % [2.7–8.1 %]) as compared to 666 glucose tolerant men (5.1 % [3.9–6.3 %]). Also in a population sample of 369 young healthy Danes the prevalence of the codon 130 variant (4.7 % [3.2–6.2 %]) was similar to what was found in Swedish Caucasians. Thus, the allelic frequency of the Thr/Ile130 variant among the control subjects in the Danish case-control study deviates from the prevalence in the two other studies which is why we consider the significant association between the codon 130 variant and NIDDM an incidental finding. In glucose tolerant subjects the codon 130 variant in its heterozygous form had no major effect on glucose-induced insulin and C-peptide release although a tendency to a lower insulin secretion during an oral glucose tolerance test was seen in middle-aged subjects. In conclusion, variability in the coding region of the HNF-4α gene is not a common cause of NIDDM among whites of Danish ancestry. However, a Val/Met255 mutation was found exclusively in NIDDM patients (0.8 % of cases) and functional as well as family segregation studies are needed to determine whether this HNF-4α variant is a NIDDM causing mutation. [Diabetologia (1997) 40: 980–983] Received: 17 April 1997 and in revised form: 28 May 1997     

Relationships between plasma measures of oxidative stress and metabolic control in NIDDM

Summary Diabetes mellitus may be associated with increased lipid peroxidation which may contribute to long-term tissue damage. To test this hypothesis, we measured hydroperoxides (ROOHs) as well as α-tocopherol in plasma from healthy subjects and individuals with non-insulin-dependent diabetes mellitus (NIDDM) (n = 41 and 87, respectively). ROOHs were analysed using the ferrous oxidation with xylenol orange version II (FOX2) assay in conjunction with a specific ROOH reductant, triphenylphosphine. α-Tocopherol was analysed by HPLC with fluorimetric detection. NIDDM patients had lower cholesterol standardised α-tocopherol levels as compared to control subjects (3.3 ± 1.0 vs 5.1 ± 2.3 (μmol/l)/(mmol/l); p < 0.0005, Mann-Whitney test): range (1.5–6.5 vs 1.9–13.0, respectively). Plasma ROOHs were substantially higher in the diabetic subjects compared to those of the control subjects (9.4 ± 3.3 vs 4.1 ± 2.2 μmol/l; p < 0.0005 Mann-Whitney test: range 2.7–16.8 vs 0.4–10.3, respectively). ROOH/cholesterol standardised α-tocopherol ratio was significantly higher in the diabetic patients compared to control subjects (3.2 ± 1.6 vs 0.9 ± 0.6; p < 0.0005, Mann-Whitney test: range 0.7–8.3 and 0.1–2.7, respectively). Plasma levels of ROOHs and α-tocopherol were similar in diabetic patients with or without complications as well as in smokers and non-smokers. The present study confirms previous findings from this laboratory that NIDDM is associated with increased oxidative stress as assessed by plasma ROOHs. Increased oxidative stress in diabetic patients appears to be related to the underlying metabolic abnormalities in diabetes, rather than to the complications of this disease. We therefore suggest that oxidative stress is an early stage in the disease pathology, which may contribute to the development of complications. [Diabetologia (1997) 40: 647–653] Received: 21 October 1996 and in final revised form: 12 February 1997     

The metabolic syndrome influences the risk of chronic complications in patients with type II diabetes

Aims/hypothesis: We examined features of the metabolic syndrome to see if they modified the risk of chronic diabetic complications in patients with Type II (non-insulin-dependent) diabetes mellitus. Methods: A total of 85 randomly selected patients with the metabolic syndrome (WHO definition) were compared with 85 Type II diabetic patients matched for age, sex, duration of diabetes, glycaemic control and without the syndrome to assess the microvascular and macrovascular complications. Results: The patients with the metabolic syndrome had a higher prevalence of cardiovascular disease (52 vs 21 %, p < 0.001), microalbuminuria or macroalbuminuria (23 vs 7 %, p = 0.003) and distal neuropathy (16 vs 6 %, p = 0.048) than patients without the syndrome. The patients with the metabolic syndrome had smaller LDL particle size (25.4 ± 1.4 vs 26.4 ± 1.1 nm; p < 0.001), which correlated with the ratio of serum triglycerides to HDL cholesterol (r = –0.64, p < 0.001). In a multiple logistic regression analysis the metabolic syndrome was associated with coronary heart disease (RR 3.84, p < 0.001) and microalbuminuria (RR 3.99, p = 0.01). Small LDL particle size was independently associated with neuropathy (RR 0.58; p = 0.04), whereas a high HbA_{1 c} was related to neuropathy (RR 1.69, p = 0.04), retinopathy (RR 1.53, p = 0.002) and microalbuminuria (RR 1.54, p = 0.01). Conclusion/interpretation: Although chronic hyperglycaemia is the main predictor of microvascular complications in patients with Type II diabetes, this risk is modified by some of the components of the metabolic syndrome. [Diabetologia (2001) 44: 1148–1154] Received: 9 February 2001 and in revised form: 17 May 2001     

Glycated Haemoglobin Levels in Patients with Diabetes in One General Practice over a 10-year Period

The aim of the study was to evaluate the level of control, as reflected by HbA_1c, in patients with diabetes attending one general practice over a 10-year period. The study was based in one general practice in South Tyneside, UK and consisted of an analysis of HbA_1c values of all patients with diabetes attending the practice between 1983 and 1992. HbA_1c levels were analysed and are presented as multiples of the standard deviation above the mean. In the practice 256 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 76 with insulin-dependent diabetes mellitus (IDDM), attended for a total of 1596 doctor/patient contacts in the diabetic clinic over 10 years. The prevalence of diabetes was 1.9%. Over the course of the clinic, in any one year, 25% of patients with NIDDM and 55% with IDDM had levels of HbA_1c above those thought to be associated with increased risk of microvascular complications. Significant reduction in glycated haemoglobin (HbA_1c) occurred in the first year after diagnosis (p < 0.01) and after changing treatment from diet alone to diet and oral hypoglycaemic agents (p < 0.001). We conclude that a large proportion of patients within this population had levels of glycaemic control that put them ‘at increased risk’.     

24-h blood pressure and autonomic function is related to albumin excretion within the normoalbuminuric range in IDDM patients

Summary Significant changes in both blood pressure, autonomic function and kidney ultrastructure are observed in insulin-dependent diabetic (IDDM) patients with microalbuminuria. Intervention strategies are evaluated at even earlier stages of disease. Identification of patients at risk of developing microalbuminuria must be based on a thorough knowledge of the relations between key pathophysiological parameters in patients with normoalbuminuria. The aim of the present study was to characterize the interactions of urinary albumin excretion (UAE), 24-h ambulatory blood pressure (AMBP), and sympathovagal balance in a large group of normoalbuminuric IDDM patients. In 117 normoalbuminuric (UAE < 20 μg/min) patients we performed 24-h AMBP (Spacelabs 90 207), with assessment of diurnal blood pressure and heart rate (HR) variation, and short-term (three times 5 min) power spectral analysis of RR interval oscillations, as well as cardiovascular reflex tests (HR variation to deep breathing, postural HR and blood pressure response). Patients with UAE above the median (4.2 μg/min) had significantly higher 24-h systolic and diastolic AMBP (125 ± 10.1/76 ± 7.2 mmHg) compared to the low normoalbuminuric group (120 ± 8.4/74 ± 5.1 mmHg), p < 0.01 and 0.02, respectively. Patients with UAE above the median had significantly reduced short-term RR interval variability including both the high frequency component (5.47 ± 1.36 vs 6.10 ± 1.43 ln ms²), and low frequency component (5.48 ± 1.18 ln ms² compared to 5.80 ± 1.41 ln ms²), p < 0.02 and p = 0.04 (ANOVA). In addition, patients with high-normal UAE had reduced mean RR level (faster heart rates) 916 ± 108 compared to 963 ± 140 ms, p < 0.04. These differences were not explained by age, duration of diabetes, gender, level of physical activity, or cigarette smoking. HbA_{1 c} was significantly higher (8.6 ± 1.2 vs 8.2 ± 1.0 %, p = 0.03) in the group with high normal UAE. Comparing normoalbuminuric IDDM patients with UAE above and below the median value, we found significantly higher AMBP in combination with significant differences in sympathovagal balance and significantly poorer glycaemic control in the group with high-normal albumin excretion. Our data demonstrate interactions between albumin excretion, blood pressure, autonomic function, and glycaemic status, already present in the normoalbuminuric range and may describe a syndrome indicative of later complications. [Diabetologia (1997) 40: 718–725] Received: 9 January 1997 and in revised form: 12 March 1997     

Mutations in the hepatocyte nuclear factor-1α gene in Caucasian families originally classified as having Type I diabetes

Summary Mutations in the hepatocyte nuclear factor-1α (HNF-1α) gene are the cause of maturity-onset diabetes of the young type 3 (MODY3), which is characterised by a severe impairment of insulin secretion and an early onset of the disease. Also at onset of diabetes some MODY patients show similar clinical symptoms and signs as patients with Type I (insulin-dependent) diabetes mellitus. The objective of this study was to estimate the prevalence of MODY3 patients misclassified as Type I diabetic patients. From a large population-based sample of unrelated Danish Caucasian Type I diabetic patients with an affected first degree relative, 39 patients (6.7 %) who did not carry any high-risk HLA-haplotypes, i. e. DR3 or DR4 or both were examined by single-strand conformational polymorphism scanning and direct sequencing of the coding region and the minimal promoter of the HNF-1α gene. Four of the 39 Type I diabetic patients (10 %) were identified as carrying mutations in the HNF-1α gene. One patient carried a missense mutation (Glu48Lys) in exon 1, two patients carried a missense mutation (Cys241Gly) in exon 4 and one patient carried a frameshift mutation (Pro291fsdelA) in exon 4. The mutations were all identified in heterozygous form, segregated with diabetes, and were not identified in 84 unrelated, healthy subjects. Furthermore, family history in three of the four families showed diabetes in four consecutive generations, suggestive of an autosomal dominant inheritance. In conclusion, about 10 % of Danish diabetic patients without a high-risk HLA-haplotype, originally classified as having Type I diabetes could have diabetes caused by mutations in the HNF-1α gene. Clinical awareness of family history of diabetes and mode of inheritance might help to identify and reclassify these diabetic subjects as MODY3 patients. [Diabetologia (1998) 41: 1528–1531] Received: 25 May 1998 and in revised form: 13 July 1998     

Effects of Insulin on Body Composition in Patients with Insulin-dependent and Non-insulin-dependent Diabetes

Insulin is used to control blood glucose but may have an adverse effect on the amount and distribution of fat mass and other cardiovascular risk factors. To test this hypothesis the effect of insulin therapy on blood glucose, body composition, and lipid levels was measured during 6 months in 9 patients with newly diagnosed insulin-dependent (Type 1) diabetes mellitus (IDDM) and 15 patients with non-insulin dependent (Type 2) diabetes (NIDDM) and secondary failure of therapy with oral hypoglycaemic agents. Both groups received similar daily doses of insulin (∼0.6 units kg⁻¹ day⁻¹). Glycaemic control improved during 6 months treatment in both groups, although the reduction in HbA_1c was greater in IDDM (5.2 ± 0.7 %) than in NIDDM (2.0 ± 0.4 %, p < 0.001). All parameters of the lipid profile improved in IDDM but not in NIDDM. Body weight, lean mass, and fat mass, measured by dual energy x-ray absorptiometry, increased at 1 month in IDDM but not in NIDDM. By 6 months, body weight had increased more in IDDM than NIDDM (9.1 ± 1.2 vs 3.77 ± 0.5 kg, p < 0.01). The increase in weight was predominantly lean mass in IDDM (60.4 ± 9.3 %) and fat mass in NIDDM (59.9 ± 8.4 %). The increase in lean mass was greater in IDDM than NIDDM (5.6 ± 1.1 vs 1.4 ± 0.3 kg, p < 0.001). Fat mass increased by similar increments in IDDM and NIDDM (3.4 ± 0.8 vs 2.4 ± 0.5 kg, p = ns) and was predominantly an increase in trunk fat (IDDM: 2.3 ± 0.6 kg, NIDDM: 2.0 ± 0.4 kg, p = ns). The central/peripheral fat mass ratio prior to treatment was lower in IDDM than NIDDM (0.64 ± 0.05 vs 1.09 ± 0.09, p < 0.01) and then increased in IDDM by 0.32 ± 0.15 (p = 0.07) and in NIDDM by 0.22 ± 0.06 (p < 0.001). In conclusion, insulin therapy is associated with weight gain in both IDDM and NIDDM. In the former, weight gain reflects increases in lean mass whereas in NIDDM it reflects an increase in trunk fat mass. It remains to be determined whether this trend to central obesity partly offsets other benefits of insulin therapy in NIDDM.     

Structural basis of diabetic nephropathy in microalbuminuric NIDDM patients: a light microscopy study

Summary The objective of the study was to evaluate early structural changes occurring in patients with non-insulin-dependent diabetes mellitus (NIDDM) and microalbuminuria by light microscopy. Basal renal biopsy was performed in patients who were subsequently randomized to different antihypertensive treatments. Fourteen NIDDM patients aged 36–65 years (duration of diabetes 9 ± 7 years) with microalbuminuria (mean urinary albumin excretion 66 ± 49 μg/min) underwent percutaneous renal biopsy. Control biopsies were obtained from five patients of similar age undergoing nephrectomy for renal neoplasia with normal renal function and no history of renal disease. Control and diabetic biopsies were processed by light microscopy and stained with haematoxylin and eosin, periodic acid Schiff, Masson's trichrome and silver methenamine. The percentage of globally sclerotic glomeruli was evaluated. Glomerular volume was determined using perimeter analysis. A semiquantitative assessment (range 0 to 3 +) was made of mesangial sclerosis, interstitial fibrosis, tubular atrophy, arteriosclerosis and arteriolar hyalinosis. Glomerular volume was significantly increased in diabetic as compared to control glomeruli (3.2 ± 8 vs 1.8 ± 7, p < 0.01). Mesangial sclerosis (0.9 vs 0, p < 0.0001) and arteriolar hyalinosis (0.91 vs 0.2, p < 0.022) were significantly higher in diabetic compared to control subjects. No significant differences between diabetic and control subjects were found in the percentage of globally sclerotic glomeruli or in the extent of interstitial fibrosis, tubular atrophy and arteriosclerosis. Thus NIDDM patients with microalbuminuria show histological findings consistent with diabetic nephropathy characterized by glomerular hypertrophy, mesangial sclerosis and arteriolar hyalinosis. However, the renal histological changes are mild and appear less marked than in insulin-dependent diabetic patients. [Diabetologia (1996) 39: 1625–1628].     

Altered ventricular repolarization during hypoglycaemia in patients with diabetes

There is circumstantial evidence implicating hypoglycaemia in the sudden overnight death of young patients with insulin-dependent (Type 1) diabetes mellitus (IDDM), the mechanism of which is unknown. We have investigated the effects of hypoglycaemia on the electrocardiogram in 15 patients with diabetes (8 with IDDM and 7 with NIDDM) using a high resolution computer-based system. Patients were randomized to either 2 h of euglycaemia or hypoglycaemia (at around 3 mmol l⁻¹ ) during the afternoon, using hyperinsulinaemic glucose clamps, the two visits separated by a period of at least 4 weeks. Corrected QT interval (QTc), plasma potassium, and adrenaline were measured at baseline and at 0, 60, and 120 min. The degree of QTc lengthening (from baseline) during clamped hypoglycaemia was greater compared to the euglycaemic control period in patients with IDDM (median{range} at 60 min, 156{8 to 258 } vs 6{−3 to 28} ms, p <0.02) and NIDDM (120 min, 128{16 to 166} vs 4{ −3 to 169} ms, p <0.05). The fall in plasma potassium was greater during clamped hypoglycaemia compared to euglycaemia in those with NIDDM ( p <0.03) but not with those with IDDM ( p >0.06). The rise in plasma adrenaline was greater during clamped hypoglycaemia in both groups (IDDM p <0.02, NIDDM p <0.02) and there was a strong relationship between the rise in adrenaline and increase in QTc ( r = 0.73, p <0.0001).These data demonstrate alteration of ventricular repolarization with lengthening of the QT interval during hypoglycaemia and suggest a possible mechanism by which hypoglycaemia could cause ventricular arrhythmias. © 1997 by John Wiley & Sons, Ltd.     

Diurnal Variation in Blood Pressure in Insulin-dependent Diabetic Smokers and Non-smokers with and without Microalbuminuria

In subjects with essential hypertension, loss of the normal nocturnal dip in blood pressure is associated with a greater risk of developing end-organ complications. In subjects with diabetes, smoking carries a similar association. To assess whether these factors may have an aetiological and synergistic role in the vascular complications of diabetes, 24-hour blood pressure monitoring was performed in insulin-dependent diabetic (IDDM) patients with normal albumin excretion (n = 19) and microalbuminuria (n = 21) of comparable age and duration of diabetes, and with no evidence of autonomic neuropathy or hypertension. The potential influence of smoking was examined by subdividing the groups, depending on smoking status. Ten of the microalbuminuric group and 9 of the normoalbuminuric group were current smokers, the remaining patients never having smoked. There was a significant difference between mean (±SD) daytime vs nocturnal blood pressure in patients with normal albumin excretion (114 ± 3/70 ± 4 vs 102 ± 3/62 ± 3 mmHg; p < 0.001) and microalbuminuria (109 ± 5/75 ± 5 vs 101 ± 3/65 ± 4 mmHg; p < 0.001) but mean blood pressure values did not differ significantly between the groups. A similar fall in nocturnal blood pressure was found in smokers and non-smokers with and without microalbuminuria (p < 0.001), but there was no difference between the mean blood pressure values in the different subgroups. In conclusion, normotensive IDDM patients, who do not have autonomic neuropathy, retain a significant diurnal variation in blood pressure, irrespective of smoking habit or presence of microalbuminuria. © 1997 by John Wiley & Sons, Ltd.     

Prospective study of development of microalbuminuria and retinopathy in Brazilian IDDM patients

With the aim to study potential risk factors for the development of microalbuminuria and retinopathy, baseline characteristics were examined in 50 Brazilian IDDM patients folowed for 4.48 years with a 2-year reexamination. During the study, 3 patients (6%) aged 25.9 ± 4.4 years, duration of diabetes 8.1 ± 4.2 years, died from acute complications without microalbuminuria and retinopathy after a follow-up of 2.1 ± 0.7 years. The standardized mortality rate for the group was 0.84 per 1000 (95% CL, 0.31, 1.83) in comparison to 0.14 per 1000 in the general population. From 34 normoalbuminuric individuals ate baseline (urinary albumin excretion rate (AER) ≤ 20 μg/min in ≥ 2 overnight urine collections), 10 developed microalbuminuria with an incidence density of 6.5 cases per 100 person-years (95%CL, 2.23, 10.16). Spontaneous normalization of AER was found in 2 of 4 patients with microalbuminuria at cycle 2. Multiple stepwise regression analysis demonstrated that baseline AET (p = 0.03), but not glycated hemoglobin, blood pressure or duration of diabetes, predicted end-of-study AER. From 36 patients without retinopathy, 10 developed nonproliferative retinopathy with an incidence density of 6.6 cases per 100 person-years (95%CL, 2.85, 10.54). Retinopathy was associated with duration (p = 0.05) and age at diagnosis of diabetes (p = 0.01). A tendency with baseline AER (p = 0.06) was also noted. No patient developed macroalbuminuria, proliferative retinopathy or hypertension. By the end of our study, in a cohort of young IDDM patients followed in a developing country, 6% died from acute complications and 15 patients (44.1%) developed retinopathy and/or microalbuminuria. Our results suggest that the only predictor of end-of-study AER was baseline AER. Also, duration of diabetes and age at diagnosis appear to be risk factors for retinopathy. Received: 22 May 1999 / Accepted in revised form: 3 March 2000     

Gastric emptying in diabetic patients by the 13C-octanoic acid breath test: role of insulin in gastric motility

Background Impairment of gastric emptying is well recognized in patients with diabetes mellitus (DM), especially long-standing insulin-dependent diabetes mellitus (IDDM). The aim of this study was to evaluate the cause of delayed gastric emptying in DM patients. Methods In 16 controls, 16 non-insulin-dependent diabetes mellitus (NIDDM) patients and 23 IDDM patients, gastric emptying was studied using the ¹³C octanoic acid breath test. Breath samples were taken before a test meal labeled with 100 mg of ¹³C octanoic acid, and at 15-min intervals over a 300-min period postprandially. Results In all DM patients, the gastric emptying coefficient was lower than that in the controls (P < 0.05), and lag time and half-emptying time were significantly longer (P < 0.05). Both NIDDM and IDDM patients showed delayed ¹³CO₂ excretion compared with the controls, but IDDM patients showed more delayed gastric emptying than NIDDM patients (P < 0.05). There were no significant differences in sex, HbA1c level, or the rate of neuropathy between the two groups. Conclusions IDDM patients showed delayed gastric emptying compared with NIDDM patients, and the ¹³C octanoic acid breath test is useful for evaluating DM patients with delayed gastric emptying.