Normal metabolism of apolipoprotein B100-containing lipoproteins despite qualitative abnormalities in type 1 diabetic men

Type 1 diabetes is not associated with an increased prevalence of hepatic steatosis

AIM

Non-alcoholic fatty liver disease (NAFLD) is commonly associated with Type 2 diabetes. Recently, it has been suggested that NAFLD is also frequently associated with Type 1 diabetes and diabetic complications. In this study, we set out to determine whether Type 1 diabetes was associated with liver fat content measured using magnetic resonance imaging.

METHODS

One hundred and twenty-eight patients with Type 1 diabetes, 264 patients with Type 2 diabetes and 67 participants without diabetes were included in this study. Hepatic steatosis was defined as a liver fat content > 5.5%.

RESULTS

People with Type 1 diabetes and controls were similar for age and BMI. Liver fat content was significantly higher in patients with Type 2 diabetes than in patients with Type 1 diabetes and controls. In the control group, nine people (13.4%) had steatosis compared with six (4.7%) patients with Type 1 diabetes (P = 0.04). Among patients with Type 2 diabetes group, 166 (62.8%) had steatosis. In multivariate analysis that included patients with Type 1 diabetes and participants without diabetes, steatosis was associated only with BMI, whereas age, sex, statin therapy and Type 1 diabetes were not. In patients with Type 1 diabetes, there was no correlation between liver fat content and estimated glomerular filtration rate or carotid intima media thickness.

CONCLUSIONS

Our data showed that Type 1 diabetes was not associated with an increased prevalence of steatosis. Moreover, our study provided no specific arguments concerning a link between liver fat content and diabetic complications in patients with Type 1 diabetes.

Effects of combination of zinc and vitamin A supplementation on serum fasting blood sugar, insulin, apoprotein B and apoprotein A-I in patients with type I diabetes

BACKGROUND AND AIM

There is accumulating evidence that shows the metabolism of zinc and vitamin A are altered in diabetes mellitus type I (DMTI), thus the present study was conducted to evaluate the effects of combination of zinc and vitamin A supplementation on serum fasting blood sugar (FBS), insulin, apoprotein B and apoprotein A-I in patients with DMTI.

DESIGN

Forty-eight, 7-year-old to 20-year-old patients with at least 2 years of DMTI history, without any metabolic condition or medicine intake with insulin treatment, participated in a randomized double-blind clinical trial for 12 weeks. They were divided into zinc and vitamin A (VAZ)-supplemented (10 mg elemental zinc per day and one-half of a 25,000 IU vitamin A tablet every other day) and/or placebo groups after matching for sex, age and DMTI duration. Nutrient intake was estimated using 24 h recall and was analyzed by food processor program. Serum apoproteins B and A-I, FBS and insulin levels were determined at the beginning and end of the trial.

RESULTS

There was significant increase in apoprotein A-I (P < 0.0001) and a significant decrease in apoprotein B (P < 0.0001) and apoprotein B/apoprotein A-I ratio (P < 0.0001) at the end of the study compared with baseline values in the VAZ group but apoprotein A-I had a significant increase (P < 0.0001) and the apoprotein B/apoprotein A-I ratio had a significant decrease (P = 0.02) at the end of study in the VAZ group compared with the control group

CONCLUSION

It seems that combined zinc and vitamin A supplementation can improve serum apoprotein A-I, apoprotein B and the apoprotein B/apoprotein A-I ratio in patients with DMTI.

Friedewald equation underestimates low-density lipoprotein cholesterol at low concentrations in young people with and without Type 1 diabetes

AIMS

Although the limitations of the Friedewald-calculated serum low-density lipoprotein cholesterol (LDL-C) are well recognized, many diabetes and lipid guidelines propose LDL-C as a therapeutic target. The validity of calculated LDL-C in people with Type 1 diabetes (T1DM) is uncertain and the use of alternatives such as non-high-density lipoprotein cholesterol (non-HDL-C) or apolipoprotein measurement unexplored. We have therefore measured LDL-C with the designated reference method and examined some of the potential sources of such bias, including plasma concentrations of other lipids and apolipoproteins.

METHODS

Seventy-four people with T1DM and 80 healthy control subjects were recruited. Fasting samples were collected for analysis of lipid profiles by a beta-quantification (BQ) reference method and by routine laboratory methods including direct HDL-C and calculation of LDL-C using the Friedewald formula.

RESULTS

Overall, Friedewald LDL-C was 0.29 +/- 0.02 (mean +/- SE) mmol/l (P < 0.001) lower in the two groups than by the BQ method. This resulted in misclassification of approximately 50% of people with a calculated LDL-C < 2.0 mmol/l. Overestimation of HDL-C by the routine assay [0.08 +/- 0.01 mmol/l (P < 0.001)] accounted for approximately 28% of the error in calculation of LDL-C and the remainder appeared to be as a result of triglyceride in lipoprotein particles other than very-low-density lipoprotein (VLDL). Correlation of non-HDL-C with apolipoprotein B was better than LDL-C with apolipoprotein B for both assays in both diabetic and non-diabetic populations.

CONCLUSIONS

Calculated LDL-C is unsuitable as a therapeutic target in T1DM. Consideration should be give to the greater use of apolipoprotein B or non-HDL-C in clinical practice.

Increased LDL cholesterol and CRP in infants of mothers with type 1 diabetes

BACKGROUND

Proatherogenic stimuli during foetal life may predispose to development of atherosclerosis in adulthood. Elevated plasma low-density lipoprotein (LDL) cholesterol and C-reactive protein (CRP) expression is associated with increased risk of atherosclerosis.

METHODS AND RESULTS

In this study, we examined how maternal type 1 diabetes affects foetal plasma LDL cholesterol and CRP. In comparison with healthy mothers, the plasma LDL cholesterol was not increased in the mothers with diabetes, however, the umbilical-cord plasma LDL cholesterol was increased in their infants. CRP was increased in infants of mothers with diabetes and high haemoglobin A1c (HbA1c, > or = 6.2%). Human placenta expresses microsomal triglyceride transfer protein (MTP), which facilitates secretion of apolipoprotein B-containing lipoproteins. Microsomal triglyceride transfer activity was slightly higher (11%) in placentas from mothers with diabetes and HbA1c > or = 6.2% compared with the controls.

CONCLUSION

The results suggest that maternal type 1 diabetes increases the foetal plasma LDL cholesterol and CRP concentration and thus might predispose the offspring to development of atherosclerosis.

Apolipoprotein B as a long-term predictor of mortality in type 1 diabetes mellitus: a 15-year follow up

OBJECTIVES

To evaluate the association of apolipoprotein B (apo B) with mortality due to all causes, to cardiac disease and to ischaemic heart disease (IHD) in subjects with type 1 diabetes mellitus.

SUBJECTS

165 subjects with type 1 diabetes included in the Swiss Cohort of the WHO Multinational Study of Vascular Disease in Diabetes were followed for 14.7+/-0.45 years.

METHODS

Causes of death were obtained from death certificates, hospital records and postmortem reports. Using a parametric proportional hazards model the association of apo B with mortality rates was assessed by time-to-event analysis, including the absolute cumulative mortality risk over time for various apo B levels at baseline.

RESULTS

Apo B was positively associated with all-cause mortality [hazard ratio (HR) 2.65 per g L-1 increase of apo B, 95% CI: 1.11-6.36, P=0.029], cardiac mortality (HR 11.64, 1.03-131.11, P=0.047) and IHD mortality (HR 9.36, 1.26-69.66, P=0.029). An apo B>or=0.96 g L-1 translated into a duplication of overall mortality hazard (HR 1.93, 1.00-3.72, P=0.050), and a sevenfold increase of mortality because of cardiac disease or IHD (HR 7.44, 1.44-38.42, P=0.017 and HR 7.38, 0.78-69.82, P=0.081). A baseline apo B of 1.5 g L-1 predicted an absolute cumulative risk to die over the next 10 years of 12.1% (5.2-31.7) for male and of 10.4% (4.7-26.1) for female subjects whereas risks were 6.3% (1.8-21.4) and 5.4% (0.8-15.8) for an apo B of 0.8 g L-1.

CONCLUSION

Apo B is consistently associated with an increased mortality in type 1 diabetes.