The importance of postpartum glucose tolerance testing after pregnancies complicated by gestational diabetes.

AIMS: To review postpartum glucose tolerance in women with gestational diabetes and evaluate the role of formal 75 g oral glucose tolerance testing vs. fasting plasma glucose in screening for persistent abnormalities. METHODS: Retrospective study of 985 pregnancies over a 10 year period in a mixed ethnic cohort of women who underwent follow-up glucose tolerance testing at 6 weeks postpartum. Diagnosis obtained by oral glucose tolerance test was tested against that from the fasting plasma glucose value. RESULTS: There were 272 abnormal postpartum oral glucose tolerance test results (27.6%), with 109 women identified as having frank diabetes. Eleven of these (10%) had fasting plasma glucose < or =6.0 mmol/l, as did 62 of 114 cases of impaired glucose tolerance. A fasting plasma glucose concentration of > or =6.1 mmol/l correctly identified abnormal glucose tolerance in 199 of 272 cases (sensitivity 0.73). South Asian women were much more likely to have persistent abnormalities of glucose tolerance than were Europeans (32 vs. 15%, chi(2)P < 0.0001). CONCLUSIONS: A postpartum fasting plasma glucose measurement alone is not sensitive enough in our population to classify glucose tolerance status accurately. A formal postpartum oral glucose tolerance test is therefore needed to facilitate early detection and treatment.

Effects of gemfibrozil on insulin resistance to fat metabolism in subjects with type 2 diabetes and hypertriglyceridaemia.

AIM: To examine whether lowering of plasma triglyceride concentrations using the fibrate peroxisome proliferator-activated receptor (PPAR)alpha agonist gemfibrozil would influence insulin sensitivity to various aspects of intermediary metabolism among subjects with type 2 diabetes mellitus. METHODS: A randomized placebo-controlled double-blind study in 12 subjects with type 2 diabetes were treated for 12 weeks after a 12-week dietary run-in. Insulin sensitivity was assessed using a low-dose incremental intravenous insulin infusion. RESULTS: Gemfibrozil significantly reduced fasting serum triglyceride concentrations (p < 0.001) but had no effect on measures of diabetic control. Neither gemfibrozil nor placebo treatment altered insulin sensitivity of glucose or glycerol metabolism during low-dose insulin infusion, but significant falls in both non-esterified fatty acid (NEFA) (p = 0.003) and ketone concentrations (p = 0.002) were observed after treatment with gemfibrozil. CONCLUSIONS: Gemfibrozil does not affect insulin sensitivity to glucose or fat metabolism in type 2 diabetes but enhances the lowering of plasma NEFA concentrations by insulin, probably by reducing hepatic fatty acid synthesis.

Risk factors for coronary heart disease in obese non-diabetic subjects.

OBJECTIVE: To examine relationships between body mass index (BMI) and coronary risk factors in obese subjects presenting to a dedicated obesity clinic. STUDY DESIGN: Cross-sectional population survey from a single centre. SUBJECTS: Three hundred and eighty-six consecutive non-diabetic obese subjects (301 women, 85 men) attending an obesity clinic for the first time (mean BMI 43.3 kg/m(2); range 30.6-71.5), aged 17-69 y (mean 40.1). MEASUREMENTS: Height, weight, resting blood pressure, fasting plasma cholesterol, triglyceride, glucose and uric acid concentrations. RESULTS: All variables measured showed an increase with higher BMI (triglycerides, P=0.04; glucose, P=0.007; urate, P<0.001; systolic BP, P<0.001; diastolic BP, P<0.001) as measured by one-way ANOVA, except cholesterol concentration which showed no relationship with BMI. In comparison with the group of subjects with BMI 30-35 kg/m(2) mean values for all variables were higher in the more obese subjects. CONCLUSIONS: Non-diabetic subjects with BMI>35 kg/m(2) carry a burden of common coronary risk factors which appears to increase with greater obesity. The risk factor pattern observed echoes that described in insulin resistance syndromes. Plasma cholesterol concentration appears not to be related to BMI.

Effects of the new oral hypoglycaemic agent nateglinide on insulin secretion in Type 2 diabetes mellitus.

AIMS: The new non-sulphonylurea oral hypoglycaemic agent nateglinide has been shown to enhance insulin secretion in animals and in healthy human volunteers and thus offers a potential advance in the treatment of Type 2 diabetes mellitus. This study examined whether nateglinide can enhance insulin secretion, and particularly the first phase insulin response, in patients with Type 2 diabetes. METHODS: A double-blind, placebo-controlled trial, examining the effects of a single oral dose of 60 mg nateglinide, given 20 min prior to an intravenous glucose tolerance test (IGTT), on insulin secretion in 10 otherwise healthy Caucasian men with recently diagnosed Type 2 diabetes (duration since diagnosis 0-44 months). RESULTS: Insulin secretion (both overall and first phase) was significantly increased by nateglinide (P < 0.001), as were C-peptide (P < 0.001) and proinsulin (P < 0.001) secretion. Overall glucose concentrations following glucose challenge were lower after nateglinide than after placebo (P = 0.05). CONCLUSIONS: Nateglinide significantly increases insulin secretion in Type 2 diabetic patients, in particular restoring the first phase insulin response. Further study is necessary to determine the effects of chronic administration on insulin secretion and blood glucose concentration.