Oxidized LDL, insulin resistance and central blood pressure after gestational diabetes mellitus.

INTRODUCTION: Gestational diabetes mellitus (GDM) is an indicator of future cardiovascular disease. We investigated whether sensitive biomarkers of increased cardiovascular risk differ between women with and without a history of GDM few years after pregnancy, and whether obesity affects the results. MATERIAL AND METHODS: We studied two cohorts - 120 women with a history of GDM and 120 controls, on average 3.7 years after delivery. Circulating concentrations of oxidized low-density lipoprotein (oxLDL) were determined by ELISA. The homeostasis model assessment of insulin resistance (HOMA-IR) index was used to estimate insulin resistance. Central blood pressure (cBP) was measured noninvasively from a radial artery pulse wave. The primary outcomes were possible differences in oxLDL, HOMA-IR or cBP between the groups. Secondly, we investigated the influence of obesity on the results, also using adjusted multiple linear regression analyses. RESULTS: OxLDL concentrations or cBP did not differ between the two cohorts, but HOMA-IR was significantly higher in women with previous GDM than in controls, 1.3 ± 0.9 (SD) and 1.1 ± 0.9, respectively (p = 0.022). In subgroup analyses, HOMA-IR (p < 0.001), systolic (p < 0.001) and diastolic (p < 0.001) cBP were significantly higher in obese subgroups compared with non-obese ones. Body mass index was an important determinant of HOMA-IR and cBP in multiple linear regression analyses. CONCLUSIONS: Over 3 years after delivery, women with GDM were still more insulin-resistant than controls. Obesity turned out to be a more important determinant of insulin resistance and cBP compared with GDM.

Comparison of the relative contributions of intra-abdominal and liver fat to components of the metabolic syndrome.

Abdominally obese individuals with the metabolic syndrome often have excess fat deposition both intra-abdominally (IA) and in the liver, but the relative contribution of these two deposits to variation in components of the metabolic syndrome remains unclear. We determined the mutually independent quantitative contributions of IA and liver fat to components of the syndrome, fasting serum (fS) insulin, and liver enzymes and measures of hepatic insulin sensitivity in 356 subjects (mean age 42 years, mean BMI 29.7 kg/m²) in whom liver fat and abdominal fat volumes were measured. IA and liver fat contents were correlated (r = 0.65, P < 0.0001). In multivariate linear regression analyses including either liver or IA fat, liver fat or IA fat explained variation in fS-triglyceride (TG) and high-density lipoprotein (HDL) cholesterol, plasma glucose, insulin and liver enzyme concentrations, and hepatic insulin sensitivity independent of age, gender, subcutaneous (SC) fat, and/or lean body mass (LBM). Including both liver and IA fat, liver and IA fat both explained variation in TG, HDL cholesterol, insulin and hepatic insulin sensitivity independent of each other and of age, gender, SC fat, and LBM. Liver fat independently predicted glucose and liver enzymes. SC fat and age explained variation in blood pressure. In conclusion, both IA and liver fat independently of each other explain variation in serum TG, HDL cholesterol, insulin concentrations and hepatic insulin sensitivity, thus supporting that both fat depots are important predictors of these components of the metabolic syndrome.

Increased liver fat, impaired insulin clearance, and hepatic and adipose tissue insulin resistance in type 2 diabetes.

BACKGROUND & AIMS: Liver fat is increased in type 2 diabetes. We determined whether it is associated with impaired insulin clearance and to what extent insulin resistance, impaired insulin clearance, or secretion contribute to fasting hyperinsulinemia. We also examined whether insulin suppression of serum free fatty acid (FFA) correlates with liver fat. METHODS: We compared 68 type 2 diabetic patients and age-, gender-, and body mass index (BMI)-matched nondiabetic subjects. Liver fat was determined by (1)H-MRS, body composition by magnetic resonance imaging, and insulin clearance and action on hepatic glucose production (HGP), glucose uptake, and serum FFA by the euglycemic insulin clamp technique (insulin 0.3 mU/kg x min) combined with infusion of [3-(3)H]glucose. RESULTS: Liver fat was 54% higher and insulin clearance 24% lower in type 2 diabetic patients than nondiabetic subjects. The percent suppression of both HGP and serum FFA by insulin were comparable, but serum insulin concentrations were significantly higher (34 mU/L [interquartile range, 30-39 mU/L] vs 25 mU/L [interquartile range, 22-30 mU/L]; P < .0001) in the type 2 diabetic than the nondiabetic subjects. When this difference was taken into account, both hepatic and adipose tissue insulin sensitivity were impaired in the type 2 diabetic subjects. Liver fat correlated with insulin clearance (r = -0.41; P = .001), and hepatic (r = 0.46; P = .0001) and adipose tissue (r = 0.55; P < .0001) insulin sensitivity. Hepatic but not peripheral insulin sensitivity was independently associated with liver fat content. Insulin clearance and secretion were independent determinants of fasting serum insulin. CONCLUSIONS: We conclude that increased liver fat, impaired insulin clearance, and hepatic and adipose tissue insulin resistance characterize type 2 diabetic patients.

Liver fat is increased in type 2 diabetic patients and underestimated by serum alanine aminotransferase compared with equally obese nondiabetic subjects.

OBJECTIVE: The purpose of this study was to determine whether type 2 diabetic patients have more liver fat than age-, sex-, and BMI-matched nondiabetic subjects and whether liver enzymes (serum alanine aminotransferase [S-ALT] and serum aspartate aminotransferase) are similarly related to liver fat in type 2 diabetic patients and normal subjects. RESEARCH DESIGN AND METHODS: Seventy type 2 diabetic patients and 70 nondiabetic subjects matched for BMI, age, and sex were studied. Liver fat ((1)H-magnetic resonance spectroscopy), body composition (magnetic resonance imaging), and biochemical markers of insulin resistance were measured. RESULTS: The type 2 diabetic patients had, on average, 80% more liver fat and 16% more intra-abdominal fat than the nondiabetic subjects. The difference in liver fat between the two groups remained statistically significant when adjusted for intra-abdominal fat (P < 0.05). At any given BMI or waist circumference, the type 2 diabetic patients had more liver fat than the nondiabetic subjects. The difference in liver fat between the groups rose as a function of BMI and waist circumference. Fasting serum insulin (r = 0.55, P < 0.0001), fasting plasma glucose (r = 0.29, P = 0.0006), A1C (r = 0.34, P < 0.0001), fasting serum triglycerides (r = 0.36, P < 0.0001), and fasting serum HDL cholesterol (r = -0.31, P = 0.0002) correlated with liver fat similarly in both groups. The slopes of the relationships between S-ALT and liver fat were significantly different (P = 0.004). Liver fat content did not differ between the groups at low S-ALT concentrations (10-20 units/l) but was 70-200% higher in type 2 diabetic patients compared with control subjects at S-ALT concentrations of 50-200 units/l. CONCLUSIONS: Type 2 diabetic patients have 80% more liver fat than age-, weight-, and sex-matched nondiabetic subjects. S-ALT underestimates liver fat in type 2 diabetic patients.

Rosiglitazone reduces liver fat and insulin requirements and improves hepatic insulin sensitivity and glycemic control in patients with type 2 diabetes requiring high insulin doses.

BACKGROUND: Liver fat is an important determinant of insulin requirements during insulin therapy. Peroxisome proliferator-activated receptor (PPAR)-gamma agonists reduce liver fat. We therefore hypothesized that type 2 diabetic patients using exceptionally high doses of insulin might respond well to addition of a PPARgamma agonist. METHODS: We determined the effect of the PPARgamma agonist rosiglitazone on liver fat and directly measured hepatic insulin sensitivity in 14 patients with type 2 diabetes (aged 51 +/- 3 yr, body mass index 36.7 +/- 1.1 kg/m2), who were poorly controlled (glycosylated hemoglobin A 1c (HbA 1c) 8.9 +/- 0.4%) despite using high doses of insulin (218 +/- 22 IU/d) in combination with metformin. Liver fat content (1H-magnetic resonance spectroscopy), hepatic insulin sensitivity [6 h hyperinsulinemic euglycemic clamp (insulin 0.3 mU/kg.min) combined with [3-3H]glucose], body composition (magnetic resonance imaging), substrate oxidation rates (indirect calorimetry), clinical parameters, and liver enzymes were measured before and after rosiglitazone treatment (8 mg/d) for 8 months. RESULTS: During rosiglitazone, HbA(1c) decreased from 8.9 +/- 0.4% to 7.8 +/- 0.3% (P = 0.007) and insulin requirements from 218 +/- 22 to 129 +/- 20 IU/d (P = 0.002). Liver fat content decreased by 46 +/- 9% from 20 +/- 3% to 11 +/- 3% (P = 0.0002). Hepatic insulin sensitivity, measured from the percent suppression of endogenous glucose production by insulin, increased from -40 +/- 7% to -89 +/- 12% (P = 0.001). The percent change in liver fat correlated with the percent decrease in HbA 1c (r = 0.53, P = 0.06), insulin dose (r = 0.66, P = 0.014), and suppression of endogenous glucose production (r = 0.76, P = 0.003). CONCLUSIONS: Our results suggest that rosiglitazone may be particularly effective in type 2 diabetic patients who are poorly controlled despite using high insulin doses. The mechanism is likely to involve reduced liver fat and enhanced hepatic insulin sensitivity.

Initiate Insulin by Aggressive Titration and Education (INITIATE): a randomized study to compare initiation of insulin combination therapy in type 2 diabetic patients individually and in groups.

OBJECTIVE: Insulin is often postponed for years because initiation is time-consuming. We sought to compare initiation of insulin individually and in groups with respect to change in A1C and several other parameters in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: A randomized (1:1), multicenter, two-arm, parallel design study with a recruiting period of up to 14 weeks and a 24-week treatment period. Either in groups of 4-8 or individually, using the same personnel and education program, 121 insulin-naive type 2 diabetic patients with an A1C of 7.0-12.0% were randomized to initiate bedtime insulin glargine. The patients visited the treatment center before and at the time of insulin initiation and at 6, 12, and 24 weeks. Patients self-adjusted the insulin dose to achieve a fasting plasma glucose 4.0-5.5 mmol/l. RESULTS: At 24 weeks, mean +/- SE A1C had decreased from 8.7 +/- 0.2 to 6.9 +/- 0.1% in those treated individually and from 8.8 +/- 0.2 to 6.8 +/- 0.1% in those in groups (not significant [NS]). Insulin doses averaged 62 +/- 5 IU and 56 +/- 5 IU at 24 weeks (NS), respectively. The frequency of hypoglycemia was similar. The total time (visits and phone calls) spent in initiating insulin in the patients in groups (2.2 +/- 0.1 h) was 48% less than in those treated individually (4.2 +/- 0.2 h). Diabetes treatment satisfaction improved significantly in both sets of patients. CONCLUSIONS: Similar glycemic control and treatment satisfaction can be achieved by initiating insulin in groups and individually. Starting insulin in groups takes one-half as much time as individual initiation.

Effects of insulin therapy on liver fat content and hepatic insulin sensitivity in patients with type 2 diabetes.

UNLABELLED: We determined whether insulin therapy changes liver fat content (LFAT) or hepatic insulin sensitivity in type 2 diabetes. Fourteen patients with type 2 diabetes (age 51+/-2 yr, body mass index 33.1+/-1.4 kg/m2) treated with metformin alone received additional basal insulin for 7 mo. Liver fat (proton magnetic resonance spectroscopy), fat distribution (MRI), fat-free and fat mass, and whole body and hepatic insulin sensitivity (6-h euglycemic hyperinsulinemic clamp combined with infusion of [3-(3)H]glucose) were measured. The insulin dose averaged 75+/-10 IU/day (0.69+/-0.08 IU/kg, range 24-132 IU/day). Glycosylated hemoglobin A1c (Hb A1c) decreased from 8.9+/-0.3 to 7.4+/-0.2% (P<0.001). Whole body insulin sensitivity increased from 2.21+/-0.38 to 3.08+/-0.40 mg/kg fat-free mass (FFM).min (P<0.05). This improvement could be attributed to enhanced suppression of hepatic glucose production (HGP) by insulin (HGP 1.04+/-0.28 vs. 0.21+/-0.19 mg/kg FFM.min, P<0.01). The percent suppression of HGP by insulin increased from 72+/-8 to 105+/-11% (P<0.01). LFAT decreased from 17+/-3 to 14+/-3% (P<0.05). The change in LFAT was significantly correlated with that in hepatic insulin sensitivity (r=0.56, P<0.05). Body weight increased by 3.0+/-1.1 kg (P<0.05). Of this, 83% was due to an increase in fat-free mass (P<0.01). Fat distribution and serum adiponectin concentrations remained unchanged while serum free fatty acids decreased significantly. CONCLUSIONS: insulin therapy improves hepatic insulin sensitivity and slightly but significantly reduces liver fat content, independent of serum adiponectin.