Accuracy of an electrochemical sensor for measuring capillary blood ketones by fingerstick samples during metabolic deterioration after continuous subcutaneous insulin infusion interruption in type 1 diabetic patients.

OBJECTIVE: This study was designed to test the accuracy of capillary ketonemia for diagnosis of ketosis after interruption of insulin infusion. RESEARCH DESIGN AND METHODS: A total of 18 patients with type 1 diabetes treated by external pump were studied during pump stop for 5 h. Plasma and capillary ketonemia and ketonuria were determined every hour from 7:00 A.M. (time 0 min = T0) to 12:00 P.M. (time 300 min = T300). Plasma beta-hydroxybutyrate (beta-OHB) levels were measured by an enzymatic end point spectrophotometric method, and capillary beta-OHB levels were measured by an electrochemical method (MediSense Optium meter). Ketonuria was measured by a semiquantitative test (Ketodiastix). Positive ketosis was defined by a value of >/=0.5 mmol/l for ketonemia and >/=4 mmol/l (moderate) for ketonuria. RESULTS: After stopping the pump, concentrations of beta-OHB in both plasma and capillary blood increased significantly at time 60 min (T60) compared with T0 (P < 0.001), reaching maximum levels at T300 (1.30 +/- 0.49 and 1.23 +/- 0.78 mmol/l, respectively). Plasma and capillary beta-OHB values were highly correlated (r = 0.94, P < 0.0001). For diagnosis of ketosis, capillary ketonemia has a higher sensitivity and negative predictive value (80.4 and 82.5%, respectively) than ketonuria (63 and 71.8%, respectively). For plasma glucose levels >/=250 mg/dl, plasma and capillary ketonemia were found to be more frequently positive (85 and 78%, respectively) than ketonuria (59%) (P = 0.017). The time delay to diagnosis of ketosis was significantly higher for ketonuria than for plasma ketonemia (212 +/- 67 vs. 140 +/- 54 min, P = 0.0023), whereas no difference was noted between plasma and capillary ketonemia. CONCLUSIONS: The frequency of screening for ketosis and the efficiency of detection of ketosis definitely may be improved by the use of capillary blood ketone determination in clinical practice.

Evolution of analytical performance in portable glucose meters in the last decade.

OBJECTIVE: To assess and compare the technical accuracy of portable glucose meters during the last decade. RESEARCH DESIGN AND METHODS: One-thousand preprandial (pre) and postprandial (post) capillary whole-blood glucose values measured with meters owned mainly by diabetic patients were compared with a single laboratory method yearly from 1989 to 1999. A total of 21,950 capillary measurements and their corresponding laboratory reference values were analyzed at our clinic. RESULTS: The lowest mean absolute difference was found in 1989 (pre: 2 +/- 22 mg/dl, post: 9 +/- 31 mg/dl) (mean +/- SD). The highest mean absolute difference was observed in 1993 (pre: 31 +/- 33 mg/dl) and 1996 (post: 50 +/- 35 mg/dl). The highest mean relative deviation was observed in 1990 (pre: 16.4%) and 1996 (post: 20.6%). The highest percentage of readings that were within a 5% deviation limit were observed in 1998 (pre: 44.5%) and in 1997 (post: 36.7%). Based on blood glucose levels within +/-5 and +/-10% of laboratory values, the technical accuracy of meters was similar for 1989 and 1999 (P = 0.27 and 0.52, respectively). The percentage of pre values in zone A of Clarke's error grid analysis was >90% in 1989, 1997, 1998, and 1999. CONCLUSIONS: The analytical performance of glucose meters decreased between 1990 and 1996 but was restored between 1997 and 1999. Nevertheless, our data suggest that the technical accuracy of glucose meters has not significantly improved during the last decade. Complementary studies taking into account the preanalytical improvements of the recent meters, as well as their calibration method, appear necessary.

Clinical performance of CGMS in type 1 diabetic patients treated by continuous subcutaneous insulin infusion using insulin analogs.

OBJECTIVE: Performance criteria have been established for in vitro blood glucose monitoring, particularly for the self-monitoring of blood glucose using glucose meters. Devices intended for use in the future, such as the continuous glucose monitoring system (CGMS), should satisfy similar criteria, particularly in diabetic patients under intensive therapy. RESEARCH DESIGN AND METHODS: The analysis was conducted on 18 type 1 diabetic patients (not controlled, HbA(1c) >7.5%) treated by external pump using insulin analogs. Each patient received a glucose sensor for 3 days during his/her hospitalization and was instructed in its operation. Medtronic criteria were used to determine the accuracy of the CGMS. In addition, the data were analyzed according to American Diabetes Association (ADA) criteria, Clarke Error Grid analysis, and method of residuals, with the glucose oxidase method using a Beckman analyzer used as the reference method. Specificity and sensitivity were evaluated from the viewpoint of accuracy in the detection of hypoglycemia. For nine patients, two glucose sensors were simultaneously inserted into an abdominal site to determine the reproducibility of the system. RESULTS-Among the 33 glucose sensors inserted, 6 (18%) were nonfunctional. The mean duration of CGMS recording was 63 +/- 12 h. From all of the 692 sets of data that paired glucose readings and CGMS, the coefficients of correlation ranged from 0.87 to 0.92 and the mean absolute error ranged from 12.8 to 15.7%. The time experienced in hypoglycemia (<55 mg/dl) was reported at 86 +/- 62 min/day. Only 39% of the CGMS values satisfied the ADA precision criteria to within +/-10%, and 19% of these values satisfied the future ADA precision criteria of accuracy to within +/-5%. The means of difference method showed that the CGMS slightly underestimated the plasma glucose values (mean = -12 mg/dl). Error grid analysis showed only 77% of the glucose sensor values were in zone A, and 98.9% were in zones A and B. Two values fell in zone C and a single value fell in zone D. The sensitivity and specificity of the CGMS to detect hypoglycemia were 33 and 96%, respectively. A total of 6666 paired sensor values were recorded with a coefficient of correlation of 0.84 with a coefficient of variation of 8.25%. CONCLUSIONS: CGMS could be useful in routine clinical practice to provide much more information on the glucose profile than intermittent self-monitoring of blood glucose (SMBG). However, CGMS cannot be used as a replacement for glucose meters because it does not satisfy the conventional performance goals set down for in vitro glucose measurements and could therefore lead to clinically incorrect treatment decisions.

French multicentric survey of outcome of pregnancy in women with pregestational diabetes.

OBJECTIVE: To evaluate perinatal outcome in pregnancies in women with type 1 and type 2 diabetes and the influence of preconception care 10 years after the St. Vincent's declaration. RESEARCH DESIGN AND METHODS: A cross-sectional study was conducted in 12 perinatal centers in France in 2000-2001. The main investigated outcomes were perinatal mortality, major congenital malformations, and preterm delivery. RESULTS: Among 435 single pregnancies, 289 (66.4%) were from women with type 1 and 146 (33.6%) from women with type 2 diabetes. Perinatal mortality rate was 4.4% (0.7% national rate), severe congenital malformations rate was 4.1% (2.2% national rate), and preterm delivery rate was 38.2% (4.7% national rate). Preconception care was provided in 48.5% women with type 1 diabetes and in 24.0% women with type 2 diabetes. Women whose first trimester HbA(1c) was >8% had higher rates of perinatal mortality (9.2 vs. 2.5%; odds ratio 3.9; 95% CI 1.5-9.7; P < 0.005), major congenital malformations (8.3 vs. 2.5%; 3.5; 1.3-8.9; P < 0.01), and preterm delivery (57.6 vs. 24.8%; 1.4; 1.1-1.7; P < 0.005) than those with first trimester HbA(1c) <8%. These results are similar to those reported in France in 1986-1988. CONCLUSIONS: Pregnancies in women with diabetes are still poorly planned and complicated by higher rates of perinatal mortality and major congenital malformations. Despite knowledge of the importance of intensified glycemic control before pregnancy, reaching the St. Vincent's target needs further implementation in France.