Post-prandial triglyceride profile in a population-based sample of Type 2 diabetic patients

Postprandial triglyceride response in normolipidemic, hyperlipidemic and obese subjects - the influence of polydextrose, a non-digestible carbohydrate

BACKGROUND

Three independent trials were conducted to evaluate postprandial triglyceride (TG) responses in subjects with different lipid metabolism. The effect of polydextrose (PDX), a soluble non-digestible carbohydrate, on postprandial response was also studied using practically relevant, high fat meal interventions.

METHODS

A total of 19 normolipidemic (average BMI 24.1 kg/m(2)), 21 overweight/hyperlipidemic (average BMI 29.6 kg/m(2)) and 18 obese/non-diabetic subjects (average BMI 33.6 kg/m(2)) were included in the study. On two separate occasions all subjects ate two high-fat meals (4293 kJ, 36% from fat), one with PDX (either 12.5 g or 15 g) and one without PDX during placebo-controlled, double-blind, crossover and randomized trials. To obtain the triglyceride measurements venous blood samples were taken before the consumption of the test meal and five times afterwards, up to 6 h post-test meal. The triglyceride responses were modeled using a mixed-effects linear model.

RESULTS

The key variables that explain the variation of the postprandial triglyceride response in the different subject groups were: baseline triglyceride concentration, time point, and PDX vs. placebo treatment (p < 0.05). The maximum postprandial TG concentration was more pronounced in hyperlipidemic group compared to normolipidemic (p < 0.001) or obese groups (p < 0.01). The modeled TG response analysis showed that irrespective of the study population PDX supplementation was one of the factors significantly reducing triglyceride response compared to the placebo treatment (p < 0.05).

CONCLUSIONS

Subjects with elevated fasting triglyceride levels display exaggerated and prolonged postprandial triglyceride responses. PDX, a soluble non-digestible carbohydrate, may offer a dietary concept for reducing the postprandial triglyceride response after the consumption of a meal containing a high concentration of fat.

The glycemic/metabolic responses to meal tolerance tests at breakfast, lunch and dinner, and effects of the mitiglinide/voglibose fixed-dose combination on postprandial profiles in Japanese patients with type 2 diabetes mellitus

BACKGROUND

Meal tolerance tests (MTTs) are usually conducted at breakfast after overnight fasting in type 2 diabetes mellitus (T2DM) patients, but differences in postprandial glycemic responses between meals have been reported.

OBJECTIVE

We conducted MTTs at breakfast, lunch, and dinner to examine the effects of a fixed combination of 10 mg mitiglinide/0.2 mg voglibose (the combination) on glycemic/metabolic responses to meals during the day in T2DM patients. MTTs with unified meals were conducted in 11 T2DM patients before and after 4 weeks of treatment with the combination administered thrice daily before meals. Glycemic/metabolic profiles measured before and at 30, 60, and 120 min after each meal were compared between each meal and between the baseline and treatment periods.

RESULTS AND CONCLUSION

The combination significantly reduced postprandial hyperglycemia after each meal. Postprandial AUC0 - 120 min for insulin significantly decreased after lunch and dinner compared with after breakfast, while insulin levels significantly increased at only 30 min after breakfast and dinner. The combination also significantly increased postprandial C-peptide and active glucagon-like peptide-1 levels, and reduced free fatty acid and triglyceride levels, but did not significantly affect glucagon levels compared with baseline, confirming that treatment with the combination improves postprandial responses in Japanese T2DM patients.

Agreement Between Fasting and Postprandial LDL Cholesterol Measured with 3 Methods in Patients with Type 2 Diabetes Mellitus

BACKGROUND

LDL cholesterol (LDL-C) is a modifiable cardiovascular disease risk factor. We used 3 LDL-C methods to study the agreement between fasting and postprandial LDL-C in type 2 diabetes (T2DM) patients.

METHODS

We served 74 T2DM patients a standardized meal and sampled blood at fasting and 1.5, 3.0, 4.5, and 6.0 h postprandially. We measured LDL-C by use of modified β quantification (MBQ), the Friedewald equation (FE), and a direct homogeneous assay (DA). We evaluated agreement using 95% limits of agreement (LOA) within ±0.20 mmol/L (±7.7 mg/dL).

RESULTS

LDL-C concentrations at all postprandial times disagreed with those at fasting for all methods. In 66 patients who had complete measurements with all LDL-C methods, maximum mean differences (95% LOA) in postprandial vs fasting LDL-C were −0.16 mmol/L (−0.51; 0.19) [−6.2 mg/dL (−19.7; 7.3)] with MBQ at 3 h; −0.36 mmol/L (−0.89; 0.17) [−13.9 mg/dL (−34; 6.6)] with FE at 4.5 h; and −0.24 mmol/L (−0.62; 0.05) [−9.3 mg/dL (−24; 1.9)] with DA at 6.0 h. In postprandial samples, FE misclassified 38% of patients (two-thirds of statin users) into lower Adult Treatment Panel III (ATP III) risk categories. Greater disagreement between fasting and postprandial LDL-C was observed in individuals with postprandial triglyceride concentrations &gt;2.08 mmol/L (&gt;184 mg/dL) and in women (interactions: P ≤ 0.038).

CONCLUSIONS

Differences up to 0.89 mmol/L (34 mg/dL) between fasting and postprandial LDL-C concentrations, with postprandial LDL-C concentrations usually being lower, were found in T2DM by 3 different LDL-C methods. Such differences are potentially relevant clinically and suggest that, irrespective of measurement method, postprandial LDL-C concentrations should not be used to assess cardiovascular disease risk.

In vivo efficacy of acyl CoA: diacylglycerol acyltransferase (DGAT) 1 inhibition in rodent models of postprandial hyperlipidemia

Postprandial serum triglyceride concentrations have recently been identified as a major, independent risk factor for future cardiovascular events. As a result, postprandial hyperlipidemia has emerged as a potential therapeutic target. The purpose of this study was two-fold. Firstly, to describe and characterize a standardized model of postprandial hyperlipidemia in multiple rodent species; and secondly, apply these rodent models to the evaluation of a novel class of pharmacologic agent; acyl CoA:diacylglycerol acyltransferase (DGAT) 1 inhibitors. Serum triglycerides were measured before and for 4h after oral administration of a standardized volume of corn oil, to fasted C57BL/6, ob/ob, apoE(-/-) and CD-1 mice; Sprague-Dawley and JCR/LA-cp rats; and normolipidemic and hyperlipidemic hamsters. Intragastric administration of corn oil increased serum triglycerides in all animals evaluated, however the magnitude and time-course of the postprandial triglyceride excursion varied. The potent and selective DGAT-1 inhibitor A-922500 (0.03, 0.3 and 3 mg/kg, p.o.), dose-dependently attenuated the maximal postprandial rise in serum triglyceride concentrations in all species tested. At the highest dose of DGAT-1 inhibitor, the postprandial triglyceride response was abolished. This study provides a comprehensive characterization of the time-course of postprandial hyperlipidemia in rodents. In addition, the ability of DGAT-1 inhibitors to attenuate postprandial hyperlipidemia in multiple rodent models, including those that feature insulin resistance, is documented. Exaggerated postprandial hyperlipidemia is inherent to insulin-resistant states in humans and contributes to the substantially elevated cardiovascular risk observed in these patients. Therefore, by attenuating postprandial hyperlipidemia, DGAT-1 inhibition may represent a novel therapeutic approach to reduce cardiovascular risk.

Postprandial lipid and apolipoprotein responses following three consecutive meals associate with liver fat content in type 2 diabetes and the metabolic syndrome

OBJECTIVE

Liver fat is associated with dyslipidemia following a fat load. Previous studies demonstrated that alimentary fat is temporarily retained within enterocytes and mobilized by subsequently ingested nutrients. As this potentially contributes to cumulative postprandial hyperlipidemia, we assessed postprandial lipoprotein changes and their association with liver fat following 3 consecutive meals during a 24 h period in males with type 2 diabetes, and men with the metabolic syndrome (MetS).

METHODS

Plasma lipids were measured in 14 type 2 diabetic, 14 MetS and 14 healthy age-matched males, following a standardized breakfast (t=0 h), lunch (t=4 h) and diner (t=8 h). Blood samples were collected before and at t=2, 4, 6, 8, 12, 16, 20 and 24 h following breakfast. Liver fat was measured by proton magnetic resonance spectroscopy.

RESULTS

Type 2 diabetic (mean age 55 (4.2) years; HbA1c 7.2 (1.1)%) and MetS men had similar BMI, waist, blood pressure and triglycerides. 24 h-AUC triglycerides, ApoB, and cholesterol-rich-remnants, but not ApoB-48, differed significantly among groups (calculated by ANOVA, all P<0.05). Liver fat was independently associated with 24 h-AUC triglycerides, ApoB and cholesterol-rich-remnants (r=0.57, P<0.001, r=0.38, P=0.017; r=0.48, P=0.002, respectively), but not with 24 h-AUC ApoB-48 (r=0.22, P=0.18).

CONCLUSIONS

In type 2 diabetes and the MetS exposure to 3 consecutive meals produced exaggerated 24 h triglyceride, ApoB and cholesterol-rich-remnant concentrations, which were closely associated with liver fat. Instead, ApoB-48 peak was delayed in type 2 diabetes, but not related to liver fat. In addition to liver fat, other mechanisms, including local intestinal processes, determine atherogenic postprandial lipoprotein changes following 3 consecutive meals during 24 h.

Effects of a plant-based high-carbohydrate/high-fiber diet versus high-monounsaturated fat/low-carbohydrate diet on postprandial lipids in type 2 diabetic patients

OBJECTIVE

To search for a better dietary approach to treat postprandial lipid abnormalities and improve glucose control in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

According to a randomized crossover design, 18 type 2 diabetic patients (aged 59 +/- 5 years; BMI 27 +/- 3 kg/m(2)) (means +/- SD) in satisfactory blood glucose control on diet or diet plus metformin followed a diet relatively rich in carbohydrates (52% total energy), rich in fiber (28 g/1,000 kcal), and with a low glycemic index (58%) (high-carbohydrate/high-fiber diet) or a diet relatively low in carbohydrate (45%) and rich in monounsaturated fat (23%) (low-carbohydrate/high-monounsaturated fat diet) for 4 weeks. Thereafter, they shifted to the other diet for 4 more weeks. At the end of each period, plasma glucose, insulin, lipids, and lipoprotein fractions (separated by discontinuous density gradient ultracentrifugation) were determined on blood samples taken at fasting and over 6 h after a test meal having a similar composition as the corresponding diet.

RESULTS

In addition to a significant decrease in postprandial plasma glucose, insulin responses, and glycemic variability, the high-carbohydrate/high-fiber diet also significantly improved the primary end point, since it reduced the postprandial incremental areas under the curve (IAUCs) of triglyceride-rich lipoproteins, in particular, chylomicrons (cholesterol IAUC: 0.05 +/- 0.01 vs. 0.08 +/- 0.02 mmol/l per 6 h; triglycerides IAUC: 0.71 +/- 0.35 vs. 1.03 +/- 0.58 mmol/l per 6 h, P < 0.05).

CONCLUSIONS

A diet rich in carbohydrate and fiber, essentially based on legumes, vegetables, fruits, and whole cereals, may be particularly useful for treating diabetic patients because of its multiple effects on different cardiovascular risk factors, including postprandial lipids abnormalities.

The honeymoon phase: intersection of metabolism and immunology

PURPOSE OF REVIEW

Even though the honeymoon phase in type 1 diabetes mellitus has been well known, its underlying pathogenic mechanisms remain poorly described. The common explanation that it occurs due to 'beta-cell rest' on initiation of insulin therapy seems inadequate based on recent observations and studies and its underlying immunological aspects overlooked.

RECENT FINDINGS

In this article, we will review the metabolic and immunological aspects of the honeymoon phase and we will present our current model of the pathophysiology of this phase. Our view is that it is one of many phases of remission occurring basically due to development of adaptive immune tolerance along the course of type 1 diabetes. We will also review new findings of the interplay between metabolic factors (ambient glucose level) and immune function.

SUMMARY

The honeymoon phase provides a unique model to understand the pathogenesis of type 1 diabetes. Research to unravel its immune pathogenesis is needed. It may turn out that the optimum form of intervention in type 1 diabetes is one that combines enhancement of antigen-specific adaptive immune tolerance with optimized metabolic control in order to keep cytotoxic T cells anergic.

Sustained postprandial decrease in plasma levels of LDL cholesterol in patients with type-2 diabetes mellitus

OBJECTIVE

Low density lipoprotein cholesterol (LDL-C) is an independent and modifiable risk factor for development of cardiovascular disease (CVD). Postprandial lipid metabolism has been linked to CVD, but little is known about the postprandial LDL-C profile in patients with type-2 diabetes (T2DM). We aimed to study the postprandial levels of LDL-C in T2DM patients.

MATERIAL AND METHODS

After an overnight fast, 74 T2DM patients, mean age approximately 60 years, were served a standard fat-rich meal of 3515 kJ containing 54% fat, 13 % protein and 33 % carbohydrates. Only drinking water was allowed postprandially. Blood samples were drawn at times 0 (fasting), 1.5, 3.0, 4.5 and 6.0 h (postprandial). In all samples, LDL-C was measured with modified beta quantification (separation by ultracentrifugation followed by measurement of infranate high density lipoprotein cholesterol (HLD-C) using a homogeneous assay).

RESULTS

At all postprandial times, levels of LDL-C showed highly significant (p < 0.005) decreases compared to time 0 (mean [95% CI] maximum change in LDL-C levels at 3.0 h: -0.16 mmol/L [-0.12; -0.20]; p < 0.001). Independently of fasting LDL-C levels and ongoing statin therapy, LDL-C decreased significantly more in female compared to male patients postprandially (mean [95% CI] maximum unadjusted change versus time 0 in LDL-C for men [n=56] at 3.0 h: -0.14 mmol/L [-0.19; -0.10], p < 0.001; for women [n=18] at 4.5 h: -0.26 mmol/L [-0.35; -0.18], p < 0.001; -0.14 mmol/L [-0.24; -0.05], p = 0.005 between genders for the mean [95% CI] fasting adjusted difference at 4.5 h in the change versus time 0 in LDL-C; gender by time interaction: p = 0.007 (repeated measures mixed model)).

CONCLUSIONS

In T2DM patients served a fat-rich meal, levels of LDL-C decreased significantly more in women compared to men postprandially, irrespective of fasting levels or ongoing statin therapy. This might have implications in the atherosclerotic process and on any difference in the risk of CVD between genders.

Postprandial glycemia and cardiovascular disease in diabetes mellitus

This article reviews the role of fasting and postprandial glycemia to the overall glycemic control of patients with type 2 diabetes and glucose intolerance, as well as their causal relationship upon micro and macrovascular complications. Recent studies have suggested that a third component of the glucose triad, the postprandial glucose excursions, might have a role in the overall glycemic load and might also reflect glycemic control. Epidemiological and intervention studies are presented in the article, supporting the conclusion that postprandial hyperglycemia in impaired glucose tolerance and diabetic subjects is a more powerful marker of cardiovascular disease risk than fasting hyperglycemia, then the treatment directed at specifically lowering postprandial glucose is crucial, as underlined by the American Diabetes Association.

Effects of monounsaturated vs. saturated fat on postprandial lipemia and adipose tissue lipases in type 2 diabetes

BACKGROUND

The effects of different dietary fatty acids on postprandial lipid metabolism in type 2 diabetic patients are still debated.

AIM

To evaluate the effects of monounsaturated (MUFA) vs. saturated fat (SAFA)-rich diets on postprandial lipemia and adipose tissue lipoprotein lipase (LPL), and hormone-sensitive lipase (HSL) in type 2 diabetes.

MATERIALS AND METHODS

Eleven type 2 diabetic patients followed, in random order, a diet rich in MUFA (SAFA 8%, MUFA 23%) and another rich in SAFA (SAFA 17%, MUFA 15%) for a period of 3 weeks each. At the end of the two diets, a standard fat-rich meal was administered and subcutaneous fat biopsies were performed at fasting and 6h after the test meal.

RESULTS

Neither diet induced significant changes in meal lipid tolerance, except for a faster (at 2h) increase in chylomicron triglycerides and a significant decrease in small VLDL triglyceride incremental area after the MUFA diet (-13.6+/-4.7 mg/dl*6h vs. -2.2+/-3.7 mg/dl*6h, p<0.005) (M+/-SEM). LPL and HSL activities were significantly increased after the MUFA diet.

CONCLUSIONS

A MUFA-rich diet reduces postprandial small VLDL triglycerides in type 2 diabetic patients compared to a SAFA-rich diet, and modifies lipolytic enzymes in adipose tissue.

Impact of metformin versus the prandial insulin secretagogue, repaglinide, on fasting and postprandial glucose and lipid responses in non-obese patients with type 2 diabetes

OBJECTIVE

Non-obese patients with type 2 diabetes (T2DM) are characterized by predominant defective insulin secretion. However, in non-obese T2DM patients, metformin, targeting insulin resistance, is non-inferior to the prandial insulin secretagogue, repaglinide, controlling overall glycaemia (HbA1c). Whether the same apply for postprandial glucose and lipid metabolism is unknown. Here, we compared the effect of metformin versus repaglinide on postprandial metabolism in non-obese T2DM patients.

DESIGN

Single-centre, double-masked, double-dummy, crossover study during 2x4 months involving 96 non-obese (body mass index < or = 27 kg/m2) insulin-naïve T2DM patients. At enrolment, patients stopped prior oral hypoglycaemic agents therapies and after a 1-month run-in period on diet-only treatment, patients were randomized to repaglinide (2 mg) thrice daily followed by metformin (1 g) twice daily or vice versa each during 4 months with 1-month washout between interventions.

METHODS

Postprandial metabolism was evaluated by a standard test meal (3515 kJ; 54% fat, 13% protein and 33% carbohydrate) with blood sampling 0-6 h postprandially.

RESULTS

Fasting levels and total area under the curve (AUC) for plasma glucose, triglycerides and free fatty acids (FFA) changed equally between treatments. In contrast, fasting levels and AUC of total cholesterol, low-density lipoprotein (LDL) cholesterol, non-high-density lipoprotein (non-HDL) cholesterol and serum insulin were lower during metformin than repaglinide (mean (95% confidence intervals), LDL cholesterol difference metformin versus repaglinide: AUC: -0.17 mmol/l (-0.26; -0.08)). AUC differences remained significant after adjusting for fasting levels.

CONCLUSIONS

In non-obese T2DM patients, metformin reduced postprandial levels of glycaemia, triglycerides and FFA similarly compared to the prandial insulin secretagogue, repaglinide. Furthermore, metformin reduced fasting and postprandial cholesterolaemia and insulinaemia compared with repaglinide. These data support prescription of metformin as the preferred drug in non-obese patients with T2DM targeting fasting and postprandial glucose and lipid metabolism.

Postprandial lipaemia in menopausal women with metabolic syndrome

BACKGROUND

The metabolic syndrome (MetS) is associated with an increased incidence of coronary heart disease (CHD). Postprandial hypertriglyceridaemia is also associated with CHD. The aim of this study was to evaluate the postprandial lipaemia after an oral fat tolerance test (OFTT) in women with MetS.

METHODS

OFTT, was given to 21 menopausal women with MetS (defined by the Adult Treatment Panel III) and to 12 healthy menopausal women. Triglyceride (TG) levels were measured before and 2, 4, 6 and 8h after the OFTT. The postprandial response was quantified by the areas under the curve (AUC) of TG levels. MetS women were subdivided according to body mass index (BMI) < or > or =30kg/m(2), and to fasting TG levels < or > or =150mg/dl.

RESULTS

The response to the OFTT was significantly higher in the MetS group compared to healthy [AUC(S.D.), in mg/dl/h; 2014(933) versus 732(197), p<0.001]. The subjects with BMI < or > or =30kg/m(2) had similar fasting TG levels [157(60)mg/dl versus 158(67) mg/dl] and AUC [1975(898) versus 2072(1044), respectively]. The MetS women with TG> or =150mg/dl had higher AUC compared to those with TG<150mg/dl [2502(854) versus 1281(441), p=0.002]. In linear regression analysis, where BMI, high-density lipoprotein cholesterol, fasting TG, HOMA-IR and QUICKI were the independent variables, only fasting TGs significantly predicted the AUC (coefficient B=11.866, p=0.008).

CONCLUSIONS

The fasting TG concentration is the main determinant of postprandial lipaemia. The obesity state was not an additional determinant for exaggerated postprandial response in MetS women. The abnormal postprandial lipaemia could be added as an important metabolic disturbance to the MetS.

Atorvastatin or fenofibrate on post-prandial lipaemia in type 2 diabetic patients with hyperlipidaemia

BACKGROUND

Post-prandial lipid abnormalities might contribute to the excess of cardiovascular risk typical of type 2 diabetic patients. The study evaluated the effects of atorvastatin (20 mg d(-1)) vs. fenofibrate (200 mg d(-1)) on post-prandial lipids in type 2 diabetic patients with mixed hyperlipidaemia.

MATERIALS AND METHOD

Eight type 2 diabetic patients, male/female (M/F) 6/2, age 58 +/- 5 years, body mass index (BMI) 28 +/- 3 kg m(-2) with cholesterol of low-density lipoprotein (LDL) between 100-160 mg dL(-1) and triglycerides between 150-400 mg dL(-1), participated in a randomized, cross-over study (3 months on atorvastatin and 3 months on fenofibrate). At baseline and at the end of the two treatments, the patients were given a standard fat meal; blood samples were taken before the meal and every 2 h after for the assay of cholesterol, triglycerides, apoB-48 and apoB-100 (determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis) in plasma lipoproteins and very low-density lipoprotein (VLDL) subfractions (large and small VLDL), separated by density gradient ultracentrifugation.

RESULTS

Data on fasting lipids confirmed that atorvastatin was more effective on the reduction of LDL-cholesterol, whereas fenofibrate was a better triglyceride-lowering agent. Concerning the post-prandial phase, the incremental areas under the curve (IAUC) for chylomicrons and large VLDL were reduced after both treatments, reaching statistical significance for cholesterol, triglyceride and apoB-100 content of chylomicrons only after fenofibrate administration [IAUC, (5.2 +/- 4.6 vs. 10.7 +/- 9.3) mg dL(-1) h(-1), P = 0.03; (131.3 +/- 95.1 vs. 259.1 +/- 201.5) mg dL(-1) h(-1), P = 0.02; (0.46 +/- 1 vs. 3 +/- 3.7) mg dL(-1) h(-1), P = 0.025, all respectively].

CONCLUSIONS

During the post-prandial state fenofibrate appeared to be more effective than atorvastatin in reducing the chylomicron response.

Nutrient determinants of postprandial triglyceride response in a population-based sample of type II diabetic patients

BACKGROUND

Nutrient determinants of postprandial triglyceride (TG) are matter of debate, especially for type II diabetes.

OBJECTIVE

This study was performed to evaluate the impact of dietary habits on postprandial TG response in a population-based sample of type II diabetic patients.

DESIGN

One-hundred and forty type II diabetic patients (63 men/77 women, age 45-70 years) referring to the same health district, not on hypolipidemic drugs and without any other chronic disease, performed four TG profiles (at fasting, before, 2 and 3 h after lunch) with a specific device (Accutrend GCT, Roche Diagnostics Mannheim, Germany) validated previously. Dietary habits were recorded by a dietitian utilizing a previously validated semiquantitative questionnaire.

RESULTS

Triglyceride values (mmol/l, mean +/- s.d.) were 2.22 +/- 0.93 at fasting, decreased before lunch (2.03 +/- 0.81), reached peak values 3 h after lunch (2.73 +/- 1.11). Postprandial TG increments (3 h after lunch minus pre-lunch concentration) significantly correlated with the intake (g/day) of animal protein (r = 0.20, P < 0.02), total fat (r = 0.21, P < 0.01), animal fat (r = 0.19, P < 0.03) and vegetable fat (r = 0.19, P < 0.03), also after adjusting for fasting TG and high-density lipoprotein cholesterol levels. Expressing nutrient intake as percentage of total calorie intake, total and animal fat remained significantly and directly related to postprandial TG increment (r = 0.21, P < 0.01 for total fat; r = 0.19, P < 0.03 for animal fat) whereas the percentage of carbohydrates was inversely related (r = -0.23, P < 0.007).

CONCLUSIONS

Fat intake seems the major nutritional determinant of postprandial TG response in type II diabetic patients.

Messenger RNA levels of genes involved in dysregulation of postprandial lipoproteins in type 2 diabetes: the role of Niemann-Pick C1-like 1, ATP-binding cassette, transporters G5 and G8, and of microsomal triglyceride transfer protein

AIMS/HYPOTHESIS

The aim of the present study was to examine the relationship between chylomicron composition and expression of genes that regulate chylomicron production in the intestine. We examined expression of the following: (1) Niemann-Pick C1-like 1 (NPC1L1), which regulates cholesterol absorption; (2) ATP-binding cassette transporters G5 and G8 (ABCG5, ABCG8), which regulate cholesterol homeostasis through their ability to excrete enterocyte cholesterol back into the lumen of the intestine; and (3) microsomal triglyceride transfer protein (MTTP), which packages the chylomicron particle by assembling cholesterol, triglyceride, phospholipids and apolipoprotein B48.

SUBJECTS, MATERIALS AND METHODS

Type 2 diabetic (26) and non-diabetic (21) patients were examined. Levels of NPC1L1, ABCG5 and ABCG8 and MTTP mRNA were measured in duodenal biopsies by real-time PCR. Lipoproteins were isolated by sequential ultracentrifugation.

RESULTS

Diabetic patients had more NPC1L1 mRNA than the control subjects (p<0.02). Expression of ABCG5 and ABCG8 mRNA was lower in the diabetic patients (p<0.05) and MTTP expression was increased (p<0.05). There was a positive correlation between NPLC1L1 and MTTP mRNA (p<0.01) and a negative correlation between NPC1L1 and ABCG5 mRNA (p<0.001). Diabetic patients on statin therapy had increased ABCG5 and ABCG8 mRNA compared to those not on statin (p<0.02 and p<0.05) and less MTTP mRNA than those not on statin (p<0.05).

CONCLUSIONS/INTERPRETATION

This study demonstrates that in type 2 diabetes there are important alterations to the expression of intestinal genes that regulate cholesterol absorption and chylomicron synthesis. In diabetic patients statin therapy is associated with reduced MTTP expression and increased ABCG5 and ABCG8 mRNA. The study suggests new mechanisms to explain postprandial diabetic dyslipidaemia and the beneficial effect of statins.