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Garry Steil, PhD

Garry Stein, PhD
Medicine Research
Critical Care Medicine Research
Hospital Title:
Academic Title:
Assistant Professor of Pediatrics, Harvard Medical School
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Research Overview

The importance of maintaining blood glucose levels within a narrow target range is well established in both the critical care setting and day-to-day lives of individuals with diabetes. In the critical care setting high blood glucose, known as stress hyperglycemia, occurs when the body’s insulin producing â-cells cannot meet the increased demand for insulin brought about as a result of the underlying critical illness1. This is similar to the conditions underlying type 2 diabetes, where the body again cannot make sufficient insulin to bring glucose levels under control, and the condition in type 1 diabetes, where the body’s â-cells have been destroyed by an underlying immune disorder. In the ICU, stress hyperglycemia has immediate detrimental effects including possibly an increased risk of mortality; in individuals with diabetes the detrimental effects can slowly manifest over time.

Dr. Steil’s research at BCH seeks to combine continuous glucose monitoring (CGM) technologies developed to aid individuals with diabetes, with insulin dosing strategies derived from understanding of how the â-cell controls blood glucose when able2. His initial research in this area was targeted toward developing an artificial pancreas3 for individuals with type 1 diabetes. Those efforts continue today, with the focus now on younger children with diabetes4. The research has also be expanded to effect better glucose control in the ICU5, 6.

About Garry Steil, PhD

Dr. Steil received a Ph.D. in Physiology and Biophysics from the University in Southern California, in Los Angeles California. Prior to receiving his Ph.D. he received a B.Sc. and a M.Sc., both in Electrical Engineering, from the University of Alberta in Edmonton Alberta Canada. He also worked as postdoctoral fellow at the Joslin Diabetes Center in Boston looking for new ways to transplant islets (another approach to addressing the insulin deficiency in type 1 diabetes), as well as in industry where he sought to develop the first commercially available artificial pancreas that could be made widely available to individuals with the disease.


Publications powered by Harvard Catalyst Profiles
  1. Bell KJ, Toschi E, Steil GM, Wolpert HA. Optimized Mealtime Insulin Dosing for Fat and Protein in Type 1 Diabetes: Application of a Model-Based Approach to Derive Insulin Doses for Open-Loop Diabetes Management. Diabetes Care. 2016 Sep; 39(9):1631-4.
  2. Bell KJ, Gray R, Munns D, Petocz P, Steil G, Howard G, Colagiuri S, Brand-Miller JC. Clinical Application of the Food Insulin Index for Mealtime Insulin Dosing in Adults with Type 1 Diabetes: A Randomized Controlled Trial. Diabetes Technol Ther. 2016 Apr; 18(4):218-25.
  3. Laxminarayan S, Reifman J, Edwards SS, Wolpert H, Steil GM. Bolus Estimation--Rethinking the Effect of Meal Fat Content. Diabetes Technol Ther. 2015 Dec; 17(12):860-6.
  4. Wolpert H, Kavanagh M, Atakov-Castillo A, Steil GM. The artificial pancreas: evaluating risk of hypoglycaemia following errors that can be expected with prolonged at-home use. Diabet Med. 2016 Feb; 33(2):235-42.
  5. Bell KJ, Smart CE, Steil GM, Brand-Miller JC, King B, Wolpert HA. Impact of fat, protein, and glycemic index on postprandial glucose control in type 1 diabetes: implications for intensive diabetes management in the continuous glucose monitoring era. Diabetes Care. 2015 Jun; 38(6):1008-15.
  6. Steil GM, Agus MS. Tight glycemic control in the ICU - is the earth flat? Crit Care. 2014; 18(3):159.
  7. Agus MS, Asaro LA, Steil GM, Alexander JL, Silverman M, Wypij D, Gaies MG. Tight glycemic control after pediatric cardiac surgery in high-risk patient populations: a secondary analysis of the safe pediatric euglycemia after cardiac surgery trial. Circulation. 2014 Jun 3; 129(22):2297-304.
  8. Decourcey DD, Steil G, Wypij D, Agus M. The authors reply. Pediatr Crit Care Med. 2014 Mar; 15(3):285-6.
  9. Steil GM. Algorithms for a closed-loop artificial pancreas: the case for proportional-integral-derivative control. J Diabetes Sci Technol. 2013 Nov; 7(6):1621-31.
  10. Steil GM, Grodsky GM. The artificial pancreas: is it important to understand how the ß cell controls blood glucose? J Diabetes Sci Technol. 2013 Sep; 7(5):1359-69.
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  12. Decourcey DD, Steil GM, Wypij D, Agus MS. Increasing use of hypertonic saline over mannitol in the treatment of symptomatic cerebral edema in pediatric diabetic ketoacidosis: an 11-year retrospective analysis of mortality*. Pediatr Crit Care Med. 2013 Sep; 14(7):694-700.
  13. Wong J, Dorney K, Hannon M, Steil GM. Cardiac output assessed by non-invasive monitoring is associated with ECG changes in children with critical asthma. J Clin Monit Comput. 2014 Feb; 28(1):75-82.
  14. Gaies MG, Langer M, Alexander J, Steil GM, Ware J, Wypij D, Laussen PC, Newburger JW, Goldberg CS, Pigula FA, Shukla AC, Duggan CP, Agus MS. Design and rationale of safe pediatric euglycemia after cardiac surgery: a randomized controlled trial of tight glycemic control after pediatric cardiac surgery. Pediatr Crit Care Med. 2013 Feb; 14(2):148-56.
  15. Wolpert HA, Atakov-Castillo A, Smith SA, Steil GM. Dietary fat acutely increases glucose concentrations and insulin requirements in patients with type 1 diabetes: implications for carbohydrate-based bolus dose calculation and intensive diabetes management. Diabetes Care. 2013 Apr; 36(4):810-6.
  16. Laxminarayan S, Reifman J, Steil GM. Use of a food and drug administration-approved type 1 diabetes mellitus simulator to evaluate and optimize a proportional-integral-derivative controller. J Diabetes Sci Technol. 2012; 6(6):1401-12.
  17. Wong J, Agus MS, Steil GM. Cardiac parameters in children recovered from acute illness as measured by electrical cardiometry and comparisons to the literature. J Clin Monit Comput. 2013 Feb; 27(1):81-91.
  18. Dauber A, Corcia L, Safer J, Agus MS, Einis S, Steil GM. Closed-loop insulin therapy improves glycemic control in children aged &lt7 years: a randomized controlled trial. Diabetes Care. 2013 Feb; 36(2):222-7.
  19. Agus MS, Steil GM, Wypij D, Costello JM, Laussen PC, Langer M, Alexander JL, Scoppettuolo LA, Pigula FA, Charpie JR, Ohye RG, Gaies MG. Tight glycemic control versus standard care after pediatric cardiac surgery. N Engl J Med. 2012 Sep 27; 367(13):1208-19.
  20. Caplow J, McBride SC, Steil GM, Wong J. Changes in cardiac output and stroke volume as measured by non-invasive CO monitoring in infants with RSV bronchiolitis. J Clin Monit Comput. 2012 Jun; 26(3):197-205.
  21. Kanderian SS, Weinzimer SA, Steil GM. The identifiable virtual patient model: comparison of simulation and clinical closed-loop study results. J Diabetes Sci Technol. 2012 Mar; 6(2):371-9.
  22. Loutseiko M, Voskanyan G, Keenan DB, Steil GM. Closed-loop insulin delivery utilizing pole placement to compensate for delays in subcutaneous insulin delivery. J Diabetes Sci Technol. 2011 Nov; 5(6):1342-51.
  23. Steil GM, Langer M, Jaeger K, Alexander J, Gaies M, Agus MS. Value of continuous glucose monitoring for minimizing severe hypoglycemia during tight glycemic control. Pediatr Crit Care Med. 2011 Nov; 12(6):643-8.
  24. Wong J, Steil GM, Curtis M, Papas A, Zurakowski D, Mason KP. Cardiovascular effects of dexmedetomidine sedation in children. Anesth Analg. 2012 Jan; 114(1):193-9.
  25. Steil GM, Eckstein OS, Caplow J, Agus MS, Walsh BK, Wong J. Non-invasive cardiac output and oxygen delivery measurement in an infant with critical anemia. J Clin Monit Comput. 2011 Apr; 25(2):113-9.
  26. Steil GM, Palerm CC, Kurtz N, Voskanyan G, Roy A, Paz S, Kandeel FR. The effect of insulin feedback on closed loop glucose control. J Clin Endocrinol Metab. 2011 May; 96(5):1402-8.
  27. Steil GM, Alexander J, Papas A, Monica L, Modi BP, Piper H, Jaksic T, Gottlieb R, Agus MS. Use of a continuous glucose sensor in an extracorporeal life support circuit. J Diabetes Sci Technol. 2011 Jan; 5(1):93-8.
  28. Rebrin K, Sheppard NF, Steil GM. Use of subcutaneous interstitial fluid glucose to estimate blood glucose: revisiting delay and sensor offset. J Diabetes Sci Technol. 2010 Sep; 4(5):1087-98.
  29. Steil GM, Hipszer B, Reifman J. Update on mathematical modeling research to support the development of automated insulin delivery systems. J Diabetes Sci Technol. 2010 May; 4(3):759-69.
  30. Keenan DB, Mastrototaro JJ, Voskanyan G, Steil GM. Delays in minimally invasive continuous glucose monitoring devices: a review of current technology. J Diabetes Sci Technol. 2009 Sep; 3(5):1207-14.
  31. Kanderian SS, Weinzimer S, Voskanyan G, Steil GM. Identification of intraday metabolic profiles during closed-loop glucose control in individuals with type 1 diabetes. J Diabetes Sci Technol. 2009 Sep; 3(5):1047-57.
  32. Steil GM, Agus MS. Critical illness hyperglycemia: is failure of the beta-cell to meet extreme insulin demand indicative of dysfunction? Crit Care. 2009; 13(2):129.
  33. Cengiz E, Swan KL, Tamborlane WV, Steil GM, Steffen AT, Weinzimer SA. Is an automatic pump suspension feature safe for children with type 1 diabetes? An exploratory analysis with a closed-loop system. Diabetes Technol Ther. 2009 Apr; 11(4):207-10.
  34. Steil GM, Reifman J. Mathematical modeling research to support the development of automated insulin-delivery systems. J Diabetes Sci Technol. 2009 Mar; 3(2):388-95.
  35. Swan KL, Dziura JD, Steil GM, Voskanyan GR, Sikes KA, Steffen AT, Martin ML, Tamborlane WV, Weinzimer SA. Effect of age of infusion site and type of rapid-acting analog on pharmacodynamic parameters of insulin boluses in youth with type 1 diabetes receiving insulin pump therapy. Diabetes Care. 2009 Feb; 32(2):240-4.
  36. Weinzimer SA, Steil GM, Swan KL, Dziura J, Kurtz N, Tamborlane WV. Fully automated closed-loop insulin delivery versus semiautomated hybrid control in pediatric patients with type 1 diabetes using an artificial pancreas. Diabetes Care. 2008 May; 31(5):934-9.
  37. Swan KL, Weinzimer SA, Dziura JD, Steil GM, Voskanyan GR, Steffen AT, Martin ML, Tamborlane WV. Effect of puberty on the pharmacodynamic and pharmacokinetic properties of insulin pump therapy in youth with type 1 diabetes. Diabetes Care. 2008 Jan; 31(1):44-6.
  38. Voskanyan G, Barry Keenan D, Mastrototaro JJ, Steil GM. Putative delays in interstitial fluid (ISF) glucose kinetics can be attributed to the glucose sensing systems used to measure them rather than the delay in ISF glucose itself. J Diabetes Sci Technol. 2007 Sep; 1(5):639-44.
  39. Wintergerst KA, Deiss D, Buckingham B, Cantwell M, Kache S, Agarwal S, Wilson DM, Steil G. Glucose control in pediatric intensive care unit patients using an insulin-glucose algorithm. Diabetes Technol Ther. 2007 Jun; 9(3):211-22.
  40. Steil GM, Rebrin K, Darwin C, Hariri F, Saad MF. Feasibility of automating insulin delivery for the treatment of type 1 diabetes. Diabetes. 2006 Dec; 55(12):3344-50.
  41. Steil G, Rebrin K, Mastrototaro JJ. Metabolic modelling and the closed-loop insulin delivery problem. Diabetes Res Clin Pract. 2006 Dec; 74 Suppl 2:S183-6.
  42. Panteleon AE, Loutseiko M, Steil GM, Rebrin K. Evaluation of the effect of gain on the meal response of an automated closed-loop insulin delivery system. Diabetes. 2006 Jul; 55(7):1995-2000.
  43. Steil GM, Rebrin K, Hariri F, Jinagonda S, Tadros S, Darwin C, Saad MF. Interstitial fluid glucose dynamics during insulin-induced hypoglycaemia. Diabetologia. 2005 Sep; 48(9):1833-40.
  44. Steil GM, Rebrin K. Closed-loop insulin delivery - what lies between where we are and where we are going? Expert Opin Drug Deliv. 2005 Mar; 2(2):353-62.
  45. Steil GM, Clark B, Kanderian S, Rebrin K. Modeling insulin action for development of a closed-loop artificial pancreas. Diabetes Technol Ther. 2005 Feb; 7(1):94-108.
  46. Steil GM, Hwu CM, Janowski R, Hariri F, Jinagouda S, Darwin C, Tadros S, Rebrin K, Saad MF. Evaluation of insulin sensitivity and beta-cell function indexes obtained from minimal model analysis of a meal tolerance test. Diabetes. 2004 May; 53(5):1201-7.
  47. Steil GM, Panteleon AE, Rebrin K. Closed-loop insulin delivery-the path to physiological glucose control. Adv Drug Deliv Rev. 2004 Feb 10; 56(2):125-44.
  48. Panteleon AE, Rebrin K, Steil GM. The role of the independent variable to glucose sensor calibration. Diabetes Technol Ther. 2003; 5(3):401-10.
  49. Steil GM, Rebrin K, Janowski R, Darwin C, Saad MF. Modeling beta-cell insulin secretion--implications for closed-loop glucose homeostasis. Diabetes Technol Ther. 2003; 5(6):953-64.
  50. Steil GM, Rebrin K, Mastrototaro J, Bernaba B, Saad MF. Determination of plasma glucose during rapid glucose excursions with a subcutaneous glucose sensor. Diabetes Technol Ther. 2003; 5(1):27-31.
  51. Jonas JC, Laybutt DR, Steil GM, Trivedi N, Pertusa JG, Van de Casteele M, Weir GC, Henquin JC. High glucose stimulates early response gene c-Myc expression in rat pancreatic beta cells. J Biol Chem. 2001 Sep 21; 276(38):35375-81.
  52. Steil GM, Trivedi N, Jonas JC, Hasenkamp WM, Sharma A, Bonner-Weir S, Weir GC. Adaptation of beta-cell mass to substrate oversupply: enhanced function with normal gene expression. Am J Physiol Endocrinol Metab. 2001 May; 280(5):E788-96.
  53. Vasir B, Jonas JC, Steil GM, Hollister-Lock J, Hasenkamp W, Sharma A, Bonner-Weir S, Weir GC. Gene expression of VEGF and its receptors Flk-1/KDR and Flt-1 in cultured and transplanted rat islets. Transplantation. 2001 Apr 15; 71(7):924-35.
  54. Jonas JC, Laybutt R, Steil GM, Trivedi N, Weir GC, Henquin JC. Potential role of the early response gene c-myc in beta-cell adaptation to changes in glucose concentration. Diabetes. 2001 Feb; 50 Suppl 1:S137.
  55. Trivedi N, Keegan M, Steil GM, Hollister-Lock J, Hasenkamp WM, Colton CK, Bonner-Weir S, Weir GC. Islets in alginate macrobeads reverse diabetes despite minimal acute insulin secretory responses. Transplantation. 2001 Jan 27; 71(2):203-11.
  56. de Souza CJ, Capotorto JV, Cornell-Kennon S, Wu YJ, Steil GM, Trivedi N, Weir GC. Beta-cell dysfunction in 48-hour glucose-infused rats is not a consequence of elevated plasma lipid or islet triglyceride levels. Metabolism. 2000 Jun; 49(6):755-9.
  57. Rebrin K, Steil GM. Can interstitial glucose assessment replace blood glucose measurements? Diabetes Technol Ther. 2000; 2(3):461-72.
  58. Trivedi N, Steil GM, Colton CK, Bonner-Weir S, Weir GC. Improved vascularization of planar membrane diffusion devices following continuous infusion of vascular endothelial growth factor. Cell Transplant. 2000 Jan-Feb; 9(1):115-24.
  59. Rebrin K, Steil GM, van Antwerp WP, Mastrototaro JJ. Subcutaneous glucose predicts plasma glucose independent of insulin: implications for continuous monitoring. Am J Physiol. 1999 Sep; 277(3 Pt 1):E561-71.
  60. Steil GM, Rebrin K, Mittelman SD, Bergman RN. Role of portal insulin delivery in the disappearance of intravenous glucose and assessment of insulin sensitivity. Diabetes. 1998 May; 47(5):714-20.
  61. Saad MF, Khan A, Sharma A, Michael R, Riad-Gabriel MG, Boyadjian R, Jinagouda SD, Steil GM, Kamdar V. Physiological insulinemia acutely modulates plasma leptin. Diabetes. 1998 Apr; 47(4):544-9.
  62. Saad MF, Riad-Gabriel MG, Khan A, Sharma A, Michael R, Jinagouda SD, Boyadjian R, Steil GM. Diurnal and ultradian rhythmicity of plasma leptin: effects of gender and adiposity. J Clin Endocrinol Metab. 1998 Feb; 83(2):453-9.
  63. Watanabe RM, Steil GM, Bergman RN. Critical evaluation of the combined model approach for estimation of prehepatic insulin secretion. Am J Physiol. 1998 Jan; 274(1 Pt 1):E172-83.
  64. Mittelman SD, Fu YY, Rebrin K, Steil G, Bergman RN. Indirect effect of insulin to suppress endogenous glucose production is dominant, even with hyperglucagonemia. J Clin Invest. 1997 Dec 15; 100(12):3121-30.
  65. Saad MF, Steil GM, Riad-Gabriel M, Khan A, Sharma A, Boyadjian R, Jinagouda SD, Bergman RN. Method of insulin administration has no effect on insulin sensitivity estimates from the insulin-modified minimal model protocol. Diabetes. 1997 Dec; 46(12):2044-8.
  66. Saad MF, Steil GM, Kades WW, Ayad MF, Elsewafy WA, Boyadjian R, Jinagouda SD, Bergman RN. Differences between the tolbutamide-boosted and the insulin-modified minimal model protocols. Diabetes. 1997 Jul; 46(7):1167-71.
  67. Steil GM, Richey J, Kim JK, Wi JK, Rebrin K, Bergman RN, Youn JH. Extracellular glucose distribution is not altered by insulin: analysis of plasma and interstitial L-glucose kinetics. Am J Physiol. 1996 Nov; 271(5 Pt 1):E855-64.
  68. Bergman RN, Watanabe R, Rebrin K, Ader M, Steil G. Toward an integrated phenotype in pre-NIDDM. Diabet Med. 1996 Sep; 13(9 Suppl 6):S67-77.
  69. Rebrin K, Steil GM, Mittelman SD, Bergman RN. Causal linkage between insulin suppression of lipolysis and suppression of liver glucose output in dogs. J Clin Invest. 1996 Aug 1; 98(3):741-9.
  70. Steil GM, Ader M, Moore DM, Rebrin K, Bergman RN. Transendothelial insulin transport is not saturable in vivo. No evidence for a receptor-mediated process. J Clin Invest. 1996 Mar 15; 97(6):1497-503.
  71. Rebrin K, Steil GM, Getty L, Bergman RN. Free fatty acid as a link in the regulation of hepatic glucose output by peripheral insulin. Diabetes. 1995 Sep; 44(9):1038-45.
  72. Watanabe RM, Lovejoy J, Steil GM, DiGirolamo M, Bergman RN. Insulin sensitivity accounts for glucose and lactate kinetics after intravenous glucose injection. Diabetes. 1995 Aug; 44(8):954-62.
  73. Youn JH, Kim JK, Steil GM. Assessment of extracellular glucose distribution and glucose transport activity in conscious rats. Am J Physiol. 1995 Apr; 268(4 Pt 1):E712-21.
  74. Steil GM, Murray J, Bergman RN, Buchanan TA. Repeatability of insulin sensitivity and glucose effectiveness from the minimal model. Implications for study design. Diabetes. 1994 Nov; 43(11):1365-71.
  75. Poulin RA, Steil GM, Moore DM, Ader M, Bergman RN. Dynamics of glucose production and uptake are more closely related to insulin in hindlimb lymph than in thoracic duct lymph. Diabetes. 1994 Feb; 43(2):180-90.
  76. Steil GM, Meador MA, Bergman RN. Thoracic duct lymph. Relative contribution from splanchnic and muscle tissue. Diabetes. 1993 May; 42(5):720-31.
  77. Steil GM, Volund A, Kahn SE, Bergman RN. Reduced sample number for calculation of insulin sensitivity and glucose effectiveness from the minimal model. Suitability for use in population studies. Diabetes. 1993 Feb; 42(2):250-6.
  78. Bergman RN, Steil GM, Bradley DC, Watanabe RM. Modeling of insulin action in vivo. Annu Rev Physiol. 1992; 54:861-83.
  79. Schwartz MW, Bergman RN, Kahn SE, Taborsky GJ, Fisher LD, Sipols AJ, Woods SC, Steil GM, Porte D. Evidence for entry of plasma insulin into cerebrospinal fluid through an intermediate compartment in dogs. Quantitative aspects and implications for transport. J Clin Invest. 1991 Oct; 88(4):1272-81.
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