Clinical outcomes of pregnancy in women with type 1 diabetes(1)

OBJECTIVE

To evaluate predictors of neonatal hypoglycemia and macrosomia in 107 consecutive pregnancies in type 1 diabetic women.

METHODS

We conducted a case record analysis of singleton type 1 diabetic pregnancies between January 1994 and January 1999 following institution of standardized management.

RESULTS

The duration of diabetes in the women was 12.9 +/- 6.8 years, and 44 were primigravidas. The mean HbA1c throughout pregnancy was 7.2 +/- 0.8%. There was no relationship between neonatal blood glucose (checked before the second feed) and HbA1c at any point in pregnancy or mean pregnancy HbA1c (R = 0.20, P >.1). However, there was a negative correlation between neonatal blood glucose and maternal blood glucose during labor (R = -0.33, P <.001). When maternal blood glucose during labor was greater than 8 mM (144 mg/dL), neonatal blood glucose was usually less than 2.5 mM (mean 1.7 +/- 0.4 mM or 31 mg/dL). There was no relationship between mean HbA1c and birth weight (R = 0.02, P >.1) or between maximum insulin dose and birth weight (R = 0.09, P >.1). Fetal abdominal circumference measured by ultrasound at 34 weeks correlated strongly with birth weight (R = 0.72, P <.001).

CONCLUSION

Neonatal hypoglycemia correlates with maternal hyperglycemia in labor, not with HbA1c during pregnancy. Macrosomia does not correlate with HbA1c during pregnancy.

Audit of influenza and pneumococcal vaccination uptake in diabetic patients attending secondary care in the Northern Region

AIMS

To document uptake of influenza and pneumococcal vaccination in diabetic patients attending secondary care in the Northern Region, and to explore influencing factors.

METHODS

Diabetic patients attending out-patients in Middlesbrough, Gateshead and Newcastle were questioned from October 1999 to March 2000. Physicians inquired about influenza and pneumococcal vaccination status using a standardized questionnaire. Data collected included age, year of diagnosis, duration of diabetes, type of diabetes, and the presence of other recognized indications for vaccination.

RESULTS

Two hundred and sixty-eight diabetic patients, 42% (113/268) with Type 1 diabetes, 34% (91/268) with ischaemic heart disease, 10% (26/268) with chronic pulmonary disease (CPD) and 10% (27/268) with chronic renal disease, were questioned. Thirty-five percent (93/268) of patients received both influenza and pneumococcal vaccines, 24% (64/268) received only influenza vaccine, and none received pneumococcus vaccine alone. Most vaccinees received advice about influenza and pneumococcal vaccination from their general practitioner (90% (142/157) and 87% (81/93), respectively). A large number of non-vaccinees were unaware of the need for influenza and pneumococcal vaccination (69% (76/111) and 91% (159/175), respectively). Using multiple logistic regression co-existing CPD increased the odds of receiving influenza (odds ratio (OR) (95% confidence interval (CI)) = 1.99 (1.07-14.12)) or pneumococcal (OR = 3.77 (1.69-21.76)) vaccination. Furthermore, each 1-year increase in age increased the chance of receiving influenza or pneumococcal vaccination by 22% (OR = 1.22 (1.09-1.67) and 29% (OR = 1.29 (1.07-1.72)), respectively.

CONCLUSIONS

Vaccination rates in these diabetic patients are unsatisfactory. Secondary care health professionals might increase rates by raising the topic in consultations. Diabet. Med. 18, 599-603 (2001)

Intra-uterine environment influences glomerular number and the acute renal adaptation to experimental diabetes

AIMS/HYPOTHESIS

We sought to test the hypothesis of whether low birth weight rats would have reduced glomerular number, higher systolic blood pressure and an altered acute response to streptozotocin diabetes compared to normal birth weight rats.

METHODS

Female offspring of Wistar rats fed an isocaloric diet containing either 6% casein (LPD) or 18% casein (NPD) in utero were studied. Birth weight, body weight, systolic blood pressure and urine albumin excretion were measured before and after streptozotocin diabetes. Glomerular number and volume were estimated after one week of diabetes.

RESULTS

The LPD rats were of low birth weight (5.4 +/- 0.5 g vs 6.4 +/- 0.8 g, p < 0.0001) with higher systolic blood pressure (137 +/- 9mmHg vs 120 +/- 7 mmHg, p < 0.0001) and reduced glomerular number (17,435 +/- 2,074 vs 24,846 +/- 1,864, p < 0.0001). The LPD rats had smaller kidneys (0.925 +/- 0.009 g vs 1.200 +/- 0.173 g, p = 0.041) but similar glomerular volume to NPD control rats (1.11 +/- 0.15 x 10(6) microm3 vs 1.08 +/- 0.17 x 10(6) microm3). After 1 week of diabetes LPD rats had a greater proportional increase in renal size (diabetes 50 +/- 12 % vs control 20 +/- 4%, p = 0.003). Insulin suppressed renal hypertrophy in both LPD and NPD rats but failed to suppress glomerular hypertrophy in LPD rats (1.48 +/- 0.21 x 10(6) microm3 vs 1.03 +/- 0.23 x 10(6) microm3 p = 0.015).

CONCLUSION/INTERPRETATION

Abnormal intra-uterine environment reduces both renal size and glomerular number and influences the acute renal adaptation to experimental diabetes.

Birth weight has no influence on glomerular number and volume

It has been proposed that low birth weight (LBW) results in a reduction in glomerular number that may, in turn, predispose an individual to develop hypertension in adulthood. Glomerular number is reduced in animal models of intra-uterine malnutrition using a variety of techniques. However, the relevance of such extreme models to man is uncertain. The purpose of this study was to evaluate whether animals with naturally occurring LBW, which have not received any manipulation in utero, have a reduction in glomerular number, altered glomerular volume and abnormal urine albumin excretion. Litters from female rats delivering at term on the same day were weighed and sexed at birth. From each litter 2 males with the lowest birth weight (LBW n = 18) and 2 males with a birth weight closest to the litter mean [normal birth weight (NBW) n = 18] were selected and cross-fostered onto periparturient lactating dams. LBW rats weighted 6.7 +/- 0.6 g compared with 7.2 +/- 0.6 g for NBW rats (P = 0.03). After weaning all rats were weighed weekly and underwent metabolic studies at 4, 8, 12 and 16 weeks. Following perfusion fixation, glomerular number and mean glomerular volume were estimated using standard stereological techniques. There was no significant difference between LBW and NBW rats with respect to glomerular number (24,499 +/- 2,078 vs. 24,825 +/- 1,818), mean glomerular volume and urine albumin excretion, and no rats had a glomerular number outside the normal range. This study suggests that naturally occurring LBW has little influence on renal development, glomerular number and volume.

Abnormal thiol group modulation of sodium-lithium countertransport and membrane fluidity is associated with a disturbed relationship between serum triacylglycerols and membrane function in type II diabetes

In essential hypertension and diabetic nephropathy, sodium-lithium countertransport (Na-Li CT) is an inherited marker, subject to metabolic influences, of cardiovascular risk. Studies in Type II diabetes, taking clinical phenotypes as their starting point, are conflicting. We sought to identify Na-Li CT kinetic abnormalities in Type II diabetes, and only subsequently to seek relationships with clinical variables. Na-Li CT kinetics, membrane fluidity and their modulation by thiol proteins were measured in erythrocytes from 38 patients with Type II diabetes and in 16 normal control subjects. In untreated erythrocytes, Na-Li CT kinetics were similar. Thiol protein alkylation with N-ethylmaleimide generally caused both V(max) and K(m) to fall, but caused K(m) to rise in erythrocytes from 13 out of 38 diabetic subjects, whose native K(m) was low (P=0. 0013 compared with control). V(max) and serum triacylglycerol levels were related in normal controls (r(s)=0.54, P=0.038) and in diabetic subjects whose K(m) fell after N-ethylmaleimide (n=25, r(s)=0.62, P=0.001). Where the K(m) rose after N-ethylmaleimide, V(max) and triacylglycerol levels were not related (n=13, r(s)=-0.39, P=0.183) and membrane fluidity did not increase after N-ethylmaleimide. However, these subgroups were indistinguishable in terms of blood pressure, albuminuria, glycaemia or lipid profiles. Thus abnormalities in the regulation of Na-Li CT and membrane fluidity by key thiol proteins, resembling those seen in essential hypertension and diabetic nephropathy, were apparent in one-third of subjects with Type II diabetes. Membrane abnormalities may indicate a common pathological mechanism. The prognostic significance of Na-Li CT kinetic abnormalities in Type II diabetes must now be confirmed.

Increased left ventricular mass index and nocturnal systolic blood pressure in patients with Type 2 diabetes mellitus and microalbuminuria

AIMS

To compare left ventricular mass (LVM) index and function in patients with Type 2 diabetes mellitus with and without microalbuminuria and to investigate the clinical determinants of left ventricular hypertrophy.

METHODS

Echocardiography, electrocardiography and 24-h ambulatory blood pressure monitoring were performed in microalbuminuric (n = 29) and normoalbuminuric (n = 29) patients with Type 2 diabetes and no clinical evidence of heart disease. Groups were individually matched for age, sex and diabetes duration and smoking status.

RESULTS

LVM index (62 (34-87) vs. 52 (33-89) g/m2.7, P = 0.04) and LVH prevalence, using two out of three definitions, were greater in patients with microalbuminuria (LVM/height2.7: 72 vs. 59%, P = 0.27, LVM/height: 66 vs. 38%, P = 0.04, LVM/body surface area: 59 vs. 31%, P = 0.03). Night-time systolic blood pressure (126 (99-163) vs. 120 (104-157) mmHg, P = 0.005) and the night/day systolic blood pressure ratio (0.92 (0.08) vs. 0.88 (0.06), P = 0.04) were higher in those with microalbuminuria. Systolic and diastolic function were similar in both groups. Linear regression analyses showed that body mass index (BMI) was significantly related to loge LVM index (R2 = 11.8%, P = 0.005) and a relationship with night/day systolic blood pressure was also suggested (R2 = 4.6%, P = 0.057).

CONCLUSIONS

In patients with Type 2 diabetes, LVH is more common and severe in those with microalbuminuria. Its presence may be related to raised night/day systolic blood pressure ratio and is significantly related to BMI. The high prevalence of LVH strengthens the case for echocardiographic screening in Type 2 diabetes to identify high risk patients who might benefit from aggressive cardiovascular risk factor intervention.

Rapid identification of Campylobacter, Arcobacter, and Helicobacter isolates by PCR-restriction fragment length polymorphism analysis of the 16S rRNA gene

A rapid two-step identification scheme based on PCR-restriction fragment length polymorphism (PCR-RFLP) analysis of the 16S rRNA gene was developed in order to differentiate isolates belonging to the Campylobacter, Arcobacter, and Helicobacter genera. For 158 isolates (26 reference cultures and 132 clinical isolates), specific RFLP patterns were obtained and species were successfully identified by this assay.

Episodic hyperglycaemia in pregnant women with well-controlled Type 1 diabetes mellitus: a major potential factor underlying macrosomia

AIMS

To test the common assumption that pregnant women who are sufficiently motivated to achieve very good HbA1c levels will record home blood glucose data accurately.

METHODS

A new device was used to download information from electronic blood glucose meters to assess the extent of selectivity in patient glucose diary-keeping.

RESULTS

In an index case, a woman with excellent ambient HbA1c (5.9%; upper limit of normal 6.1%) was observed to have 68% of preprandial blood glucose readings above the target range of 3.5-6.5 mmol/l and a mean (+/- SD) level of 8.9+/-3.9 mmol/l in the corresponding period. No such impression was conveyed by the home monitoring diary. Six pregnant women with well controlled Type 1 diabetes (mean HbA1c 6.6+/-0.2%) exhibited between 42 and 68% of preprandial readings above the target range.

CONCLUSIONS

The frequency of hyperglycaemia has hitherto been underestimated in well controlled pregnant women whose near-perfect home monitoring record is apparently corroborated by near-normal HbA1c levels. These observations provide a hypothesis for understanding of the disappointing continuance of macrosomia despite excellent HbA1c levels throughout pregnancy.

Dysregulation of PMN antigen expression in Type 2 diabetes may reflect a generalized defect of exocytosis: influence of hypertension and microalbuminuria

Defective exocytosis could underlie clinical and metabolic abnormalities in Type 2 diabetes. Because many SNARE proteins appear to be common mediators of exocytosis, we examined phorbol myristate acetate-stimulated expression of CD11b and CD69 on polymorphonuclear leukocytes (PMN) from Type 2 diabetic subjects with hypertension and microalbuminuria (D-htma), hypertension only (D-ht) or uncomplicated (D-uc), and normal controls (NC) by flow cytometry. CD11b expression was rapid (half maximal by 7 min), initially on all PMN. CD69 expression took place subsequently but on PMN that did not express CD11b. The proportion of CD11b-positive PMN at 30 min was higher in all diabetic groups than in NC. Expression of CD11b was higher and CD69 lower in D-uc and D-htma but were similar in NC and D-ht. In Type 2 diabetes the transition from the CD11b-positive to CD69-positive state is impaired. The defect in the process of CD69 expression appeared most marked in diabetic subjects with hypertension and microalbuminuria.

Blood pressure control, microalbuminuria and cardiovascular risk in Type 2 diabetes mellitus

Type 2 (noninsulin-dependent) diabetes mellitus (DM) affects about 3% of the UK population. Diabetes often coexists with a cluster of other potent cardiovascular risk factors, including hypertension, dyslipidaemia and increased tendency for thrombosis, and increases the risk of early death from cardiovascular causes by about threefold. Microalbuminuria or proteinuria also may be present, further increasing the risk of cardiovascular mortality. Cardiovascular risk factors must be treated aggressively in patients with Type 2 diabetes and control of blood pressure at 140/85 mm Hg or lower is a priority. The management of hypertension in patients from some ethnic groups demands special consideration because they have a high incidence of diabetes and hypertensive complications. Patients must be urged to adopt appropriate lifestyle changes in the first instance but additional drug treatment for hypertension is usually required. All the major classes of antihypertensive agents lower blood pressure in Type 2 diabetic patients but have different effects on metabolic risk factors in different ways. Low-dose thiazide diuretics, beta-blockers, calcium channel blockers and angiotensin converting enzyme (ACE) inhibitors have been shown to reduce cardiovascular risk. Individually, the effects of low-dose thiazide diuretics and beta-blockers on glucose and lipid metabolism is clinically insignificant, though in combination much larger metabolic effects are seen. ACE inhibitors and calcium channel blockers have no, or small, beneficial effects on glucose and lipid metabolism, while the greater beneficial effects of alpha1-blockers on lipid profiles may render them especially useful in the Type 2 diabetic patient. Long-acting calcium-channel blockers and ACE inhibitors protect renal function and are suitable as first line therapy in patients with microalbuminuria or proteinuria. Until results from the current batch of randomized, placebo-controlled trials comparing different classes of antihypertensive agents are available, the choice of antihypertensive agent is difficult. Addressing overall cardiovascular risk factors, rather than hypertension alone, is essential in the management of the hypertensive Type 2 diabetic patient.

Silent myocardial ischemia and microalbuminuria in asymptomatic subjects with non-insulin-dependent diabetes mellitus

Microalbuminuria is an increase in urinary albumin not detected by conventional dipstick testing and is present in 20% of patients with non-insulin-dependent diabetes mellitus (NIDDM). Mortality in NIDDM patients with microalbuminuria is 60% at 8 years and is mainly due to cardiovascular disease. Because many deaths occur without warning symptoms, we have compared the prevalence and severity of silent myocardial ischemia in asymptomatic NIDDM patients with and without microalbuminuria. We have performed a cross-sectional, case-control study of asymptomatic NIDDM patients attending hospital diabetes clinics. Forty-three patients with microalbuminuria were matched for age, gender, diabetes duration, and smoking status with 43 normoalbuminuric patients. A symptom-limited exercise stress test was performed and reported blind to patient status. The degree of electrocardiographic ST-segment depression, exercise time, work performed, and maximum heart rate with exercise were recorded. Patients with microalbuminuria had a higher prevalence of ischemic response (>1 mm ST depression) (65% vs 40%, p = 0.016), reduced total exercise time (5 vs 7 minutes, p <0.001), reduced work (6 vs 8 METs, p <0.001), and reduced age-predicted maximum heart rate (94% vs 101%, p = 0.004). In multiple logistic regression, albumin excretion rate was shown to be the strongest independent predictor of ischemic response (p = 0.03). Silent myocardial ischemia is common in asymptomatic NIDDM patients but is more common in those with microalbuminuria. In these subjects, the higher prevalence of ischemic response at low workloads suggests a higher probability of future coronary events, and possibly a higher probability of potentially treatable coronary artery disease.

Autonomic neuropathy in asymptomatic subjects with non-insulin-dependent diabetes mellitus and microalbuminuria

Patients with non-insulin-dependent diabetes mellitus (NIDDM) and microalbuminuria (MA) are at increased risk of early death. In NIDDM patients without evidence of heart disease, we examined the links between MA and autonomic neuropathy (AN) and reduced heart rate variability (HRV), both of which have been linked to a poor prognosis. We have studied 43 asymptomatic NIDDM patients with MA and have matched them with 43 normoalbuminuric patients for age, gender, diabetes duration, and smoking status. AN was assessed by heart rate changes to deep breathing, Valsalva, and posture and blood pressure changes to posture and hand grip. Twenty-four hour Holter monitoring was used to evaluate HRV. Patients with MA showed evidence of AN and reduced HRV when compared with normoalbuminuric patients. In multivariate analysis, with measures of AN and HRV as outcome variables, Log albumin excretion rate was a significant independent predictor but stronger predictors were the presence of diabetic retinopathy, age, body mass index, claudication, alcohol consumption, and calcium channel blocker use. The presence of MA is linked to AN and reduced HRV in asymptomatic NIDDM patients. The nature of the relationship is complex, involving multiple relationships with other clinical parameters.

British Diabetic Association guidelines on genetic and immune screening for type 1 diabetes mellitus

The following article is a report from the Chairman of the Professional Advisory Committee of the British Diabetic Association. The committee, with the help of a number of experts currently working in the field, produced a set of guidelines intended for use by health care professionals on the issues around genetic screening for Type 1 diabetes mellitus. The guidelines were approved by the Board of Management of the British Diabetic Association and we publish them here.

Abnormal regulation of cell membrane fluidity in diabetic nephropathy

An abnormality of the physical properties of the cell membrane may underlie the defect that unites the clinical and biochemical abnormalities found in subjects with diabetic nephropathy. The cell membrane is linked both structurally and functionally with the cytoskeleton. The fluorescence anisotropy, a measure of membrane fluidity, was studied at baseline and after modulation of cytoskeletal proteins by thiol group alkylation with N-ethylmaleimide (NEM). 1,6-diphenyl-1,3,5-hexatriene (DPH) was used to assess anisotropy in the deep hydrophobic regions of the lipid bilayer and trimethylammonium-diphenylhexatriene (TMA-DPH) was used to assess the superficial, relatively hydrophilic regions. We compared 17 subjects with insulin-dependent diabetes mellitus (IDDM) and nephropathy with 17 control subjects with IDDM and 24 non-diabetic control subjects. Median TMA-DPH anisotropy (0.271 (0.239-0.332) vs 0.269 (0.258-0.281) vs 0.275 (0.246-0.287)) and DPH anisotropy (0.221 (0.193-0.261) vs 0.227 (0.197-0.253) vs 0.226 (0.193-0.245)) were similar in erythrocytes from the three groups. However after alkylation of protein thiol groups with NEM clear differences emerged. In the control subjects with and without IDDM there was a significant fall in TMA-DPH anisotropy compared to the subjects with diabetic nephropathy in whom the addition of NEM had no effect (deltaTMA-DPH anisotropy -0.005 (-0.020 - +0.006) vs -0.005 (-0.011 - +0.016) vs +0.002 (-0.010 - +0.008) p < 0.001). This finding was confirmed when the deep regions of the lipid bilayer were assessed using DPH (deltaDPH anisotropy -0.017 (-0.029 - -0.007.) vs -0.015 (-0.029 - +0.001) vs + 0.003 (-0.021 - +0.018) p < 0.001). We conclude that cytoskeletal modulation of the physical properties of the cell membrane lipids by proteins is abnormal in subjects with diabetic nephropathy. Such an abnormality could explain some of the clinical and metabolic abnormalities found in this condition.

Renal autoregulation is normal in newly diagnosed, normotensive, NIDDM patients

Abnormalities of renal autoregulation with glomerular hyperfiltration and raised intraglomerular pressure have been suggested as important factors in the initiation and development of diabetic nephropathy. Angiotensin converting enzyme (ACE) inhibition appears to have a specific reno-protective role in diabetic nephropathy, possibly by reducing intraglomerular pressure. The acute effects of ACE inhibition on renal haemodynamics in normotensive, non-insulin-dependent diabetes mellitus (NIDDM) have not been previously reported. We measured simultaneous glomerular filtration rate (GFR) and renal plasma flow (RPF) in 29 (4 female) subjects, mean age 52 years (range 27-70), using 51Cr EDTA and 125I Hippuran. Clearances were corrected to 1.73 m(-2). All patients were normotensive (blood pressure < 75th centile for age and sex), newly diagnosed (< 30 days), taking no antihypertensive or hypoglycaemic medication. Subjects were randomly allocated (double blind) to receive the ACE inhibitor trandolapril 4mg day(-1) (H) (hypotensive dose), trandolapril 0.5 mg day(-1)(L) (non-hypotensive dose) or placebo (P) for 10 days after which renal haemodynamics were remeasured. For all subjects baseline GFR, RPF and filtration fraction (FF) were 97+/-21 ml min(-1) mean+/-SD, 439+/-120 ml min(-1) and 22.3+/-2.9 % respectively. Glomerular hyperfiltration (GFR> 120 ml min[-1]) was only demonstrated in 3 subjects (10.3 %). In group H mean arterial pressure (103+/-8 vs 93+/-9 mmHg, p < 0.001) and FF (23.8+/-2.3 vs 20.0+/-4.0%, p = 0.03) fell while RPF increased (376+/-111 vs 426+/-60 ml min(-1), p = 0.02), there was no significant change in GFR. No significant change in mean arterial pressure, GFR, RPF or FF occurred in groups P and L. These studies suggest that in newly diagnosed normotensive NIDDM subjects normal renal autoregulation occurs and glomerular hyperfiltration is uncommon.

Lack of association of angiotensin II type 1 receptor gene polymorphism with diabetic nephropathy in insulin-dependent diabetes mellitus

Several observations suggest that inherited factors are influential in the development of nephropathy in patients with insulin-dependent diabetes mellitus (IDDM). Genetic components of the renin angiotensin system are possible candidate genes. The aim of this study was to determine the role of the hypertension associated angiotensin II type 1 receptor (AT1R) gene A1166C polymorphism in susceptibility to nephropathy in IDDM. We examined 264 Caucasoid patients with IDDM and overt nephropathy (as defined by persistent proteinuria in the absence of other causes, hypertension and retinopathy), 136 IDDM patients with long duration of diabetes and no nephropathy (LDNN group), 200 recently diagnosed IDDM patients (Sporadic Diabetic group), and 212 non-diabetic subjects. The AT1R gene polymorphism was assessed using the polymerase chain reaction and restriction isotyping. Genotype frequencies did not differ significantly between the sporadic diabetic group and the nephropathy group (p = 0.245), nor between the long duration non-nephropathy group and the nephropathy group (p = 0.250). Allele frequencies were not significantly different between the three groups (p = 0.753). We conclude that there is no significant association between the hypertension associated AT1R gene polymorphism and diabetic nephropathy in patients with IDDM in the UK.