Aims: To use continuous glucose monitoring (CGMS) to compare glucose profiles in people with type 1 diabetes following injection of insulin into an area affected by lipohypertrophy vs. an area not affected by lipohypertrophy.
Methods: Eight patients with type 1 diabetes underwent 72 h of CGMS while following a standardized diet and injecting all insulin either into an area with or without lipohypertrophy. Patients underwent two testing periods in random order, separated by 4 days. On day 1 of each test subjects were admitted for measurement of insulin and plasma glucose levels immediately prior to, and hourly for 4 h following, a standardized lunch.
Results: Insulin area under the curve (AUC)(0-4 h) was similar for both test periods; 656; interquartile range (IQR): 518-1755 (normal tissue) vs. 602; IQR: 382-1436 (lipohypertrophic tissue), z = 1.7, p = 0.09. There was also no difference in the median time to maximal insulin concentration (Time(max) 2 h; IQR: 2-3 h; z = 0.6; p = 0.6). There was a 37.5% increase in mean plasma glucose levels following a standardized meal; however this was not significant between sites (AUC(0-4 h)t = -1.7; p = 0.1). Moreover, there was no difference in CGMS profiles (AUC(1-72 h)t = -0.9; p = 0.4) across the 72-h monitoring period. Overall the prevalence of hypoglycaemia (CGMS readings < 4 mmol/l) was similar between injection sites (11.6 vs. 10.6%, p = 0.1).
Conclusion: The pharmacokinetic and pharmacodynamic effect of injecting into lipohypertrophic tissue is small in comparison to the usual clinical variation observed with insulin injections.