Alternative methods for self-monitoring of blood glucose have been pursued by many researchers, largely in response to evidence gathered in several long-term studies of patients with diabetes mellitus. These studies suggest that long-term complications of the disease may be mitigated if the disease is intensively managed, a component of which is increased monitoring. Many of the alternative methods utilize interstitial fluid (ISF) as the diagnostic fluid, rather than finger blood. A time lag in the distribution of glucose from blood to the interstitium has been observed by many, with estimates of lag time varying from none to 45 min. Dermal ISF was sampled from diabetic subjects in two tests and compared to finger blood glucose. In the first test, data were collected over time in a manner that allowed a cross-correlation analysis to predict an average lag time. Information from this test was then used as input to a data collection format for a method comparison test of 691 patients with diabetes in which ISF data were collected immediately after the finger blood reference and 15 min after the reference. An average lag time of about 25 min was determined from the cross-correlation analysis, with the correlation error reduced by three-fourths within a 15-min lag time. In the method comparison test, the correlation coefficient between finger blood glucose and ISF glucose improved from 0.923 to 0.951, and the percentage of data in the A zone of the Clarke Error Grid rose from 80.2% to 90.6% for the ISF glucose data collected at no lag and 15-min lag, respectively. Dermal ISF glucose measurement might be a reasonable alternative to blood glucose measurement for patients routinely monitoring ambient glycemia, although more testing in the sensitive hypoglycemic range is needed to clarify what might happen in cases of rapidly changing glucose.

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The displacement of a significant amount of diesel fuel with natural gas during large scale fracturing and drilling developments can be economically feasible in many cases with minor modifications to most diesel engines using dual fuel technology. Dual fuel describes the combination of a pressure and volume regulated stream of natural gas flowing through the engine intake and mixing with a reduced amount of injected diesel fuel in the engine to create power output that is nearly indistinguishable from using straight diesel fuel in high pressure fracturing pumps and other support equipment. Combining diesel fuel and natural gas in a dual fuel system reduces emissions of NOx, SOx, CO2, VOCs and particulates. Diesel fuel volume has been reduced by as much as 1,575 gallons per frac stage in field testing (63% of total fuel). Engine modification is with primarily bolt-on aftermarket and factory kits. Fuel savings vary depending on price and availability of the natural gas fuel source: LNG (liquid form) from existing liquefaction and/or storage infrastructure or CNG (gaseous form) from local distribution companies (LDC), and/or field gas or distribution gas pipeline systems. Learnings presented from field trials include a case history of frac jobs using CNG, LNG and other gas supply. Economic data is presented on the overall process. Recognition that availability of adequate CNG and LNG fuel supplies may be limiting expanded implementation of dual fuel technologies has prompted us to consider methods of making both fuel supplies more available to other industrial segments as well as the oil and gas industry.