TYPE I DIABETES Flashcards
Type I Diabetes
- pancreas doesn’t produce enough insulin
- islets of langerhans play a crucial role in glucose homeostasis
- islets are predominantly made up of insulin-secreting beta cells and glucagon secreting alpha cells
- beta cells are destroyed by autoimmune destruction of insulin producing beta cells resulting in hyperglycaemia
Hyperglycaemia Definition
- excess of glucose in the blood stream
- high blood sugar
Beta Cell Destruction
- insulin binds to receptor
- Akt signal cascade
- GLUT-4 translocation
- glucose entry permitted
Beta Cell Destruction - Microvascular Impacts
- retinopathy
- nephropathy
- neuropathy
Beta Cell Destruction - Macrovascular Impacts
- cerebrovascular disease
- coronary artery disease
- peripheral artery disease
Laing et al., 2003 - T1D
- associated with greater heart disease risk and mortality compared with age matched people without diabetes
- lower life expectancy in T1D
Insulin Therapy
- two primary administration methods; insulin pen, and insulin pump
- both injected into subcutaneous layer
Insulin Analogues
- developed to better mimic physiological insulin secretion
- human insulin clusters together
- re-arranging amino acids or adding to the structure of insulin means clustering can be lessened or encouraged to change properties
- rearrange amino acid structure to go from peptide hormone to effectively a protein
Insulin Analogue Profiles - Bolus
- rapid action insulins
- take alongside a meal
- counters steep rise in blood glucose from the meal
Insulin Analogue Profiles - Basal
- background, longer lasting insulin
- inject 1/2 times a day
- slow release - doesn’t all spill into the blood stream at once
Battelino et al., 2019 - Blood Glucose Levels
- hypoglycaemia <3.9mmol/L (<70mg/dL)
- hyperglycaemia >10mmol/L (>180mg/dL)
Cryer et al., 2008 - Hypoglycaemia
- no pancreatic insulin release; altered alpha-beta cell signals (reduced glucagon release); exogenous insulin poorly regulated
- attenuated AD response to falling BG (IAH)
- antecedent hypoglycaemia, and a reduced SNS response means the AD response to falling BG is shifted to a lower threshold
Managing T1D
- blood glucose check
- HbA1c check
- food diary and blood glucose log
- continuous glucose monitoring systems
Bohn et al., 2015 - Health Benefits of Exercise
- better glycaemia
- better BM
- better blood pressure (except SBP)
- combats risk of T1D specific concomitant conditions
- related to a reduced HbA1c
- better blood lipids
- fewer complications (except severe hypos)
Bohn et al., 2015 - Benefits of Regular Exercise
- lower blood pressure
- improved muscle health, strength and function
- improved bone health - lower risk of osteoporosis and fractures
- improved insulin sensitivity and exercise (induced glucose uptake lead to lower insulin requirements
- lower risk of diabetic neuropathy and nephropathy
- possible beta cell preservation
- greater aerobic capacity
Colberg et al., 2015 - Factors That Affect BG During Exercise
- exercise
- environment
- regimen changes (starting BG levels, food intake etc)
- bodily concerns
- hypoglycaemia-associated autonomic failure
Brazeau et al., 2008 - Barriers to PA
- frequency of hypoglycaemia
- busy work schedule
- loss of gylcaemic control
- pre-existing low levels of fitness
Acute Exercise Management Strategy
Fall:
- decrease insulin
- increase CHO intake
Rise:
- omit/increase insulin
- decrease/omit CHO intake
McCarthy et al., 2020 - Aerobic Exercise on BG
- glucose production outweighed by uptake from cells
- glucose uptake is insulin dependant and independent
- blood glucose declines
Management Strategies Around Exercise
- check glucose regularly
- additional CHO intake
- adjustment to insulin dosing
West et al., 2010 - Pre-Ex Rapid-Acting Insulin and BG
- 75% reduction in pre-ex insulin results in greatest preservation of blood glucose, and a reduced dietary intake, for 24h after running
West et al., 2011 - LGI CHO Ingestion Pre-Exercise
- LGI CHO 2h pre-ex better preserved post-ex glucose for 3h compared to isoenergetic HGI CHO
- bolus insulin reduction LGI CHO adjustments made 30min before running produced similar post-run BG concs as those at 2h pre-ex
- LGI CHO consumption and reduced rapid acting insulin need to not be made 24h pre-ex
Campbell et al., 2015 - Glargine and Exercise
- 20% reduction in glargine and bolus insulin reduction eliminates nocturnal hypoglycaemia
Heise et al., 2016 - Post-Exercise Hypoglycaemia
- same risk of post-ex hypoglycaemia on deglude as glargine
Van Dijk et al., 2016 - Daily Walking Exercise
- 26±16% reductions in daily insulin requirements in daily walking 40-50km over 4 days
McMahon et al., 2007 - Strategies to Reduce Post-Ex Hypoglycaemia
Nutritional intake
- LGI CHO meal (1g CHO/kg) 1-2h after ex to reduce early onset hypoglycaemia and replenish glycogen stores
- if ex is done in late afternoon/evening, small pre-bed LGI CHO snack (~0.4gCHO/kg) without insulin to reduce nocturnal hypos
- include protein in post-ex meals to reduce risk of ‘double-dip’ hypos
Glucose Monitoring
- frequent monitoring of glucose/ CGM for several hours post-ex
Fahey et al., 2012 - Sprinting and BG
- 10s sprint causes decline in glucose Rd rather than form a disproportionate rise in glucose Ra relative to glucose Rd as reported with intense aerobic exercise
Harmer et al., 2007 - Sprinting and BG
- acute intermittent maximal exercise causes hyperglycaemia in T1D and con
- affect attenuated by regular exercise
Bassau et al., 2006 - Sprint After Aerobic-Ex
- 10s max-effort sprint after moderate intensity-ex provides another means to reduce hypoglycaemia
Bassau et al., 2007 - Sprint Before Aerobic-Ex
- 10s max-effort sprint performed immediately before moderate intensity-ex prevents glycaemia from falling during early recovery from moderate-intensity-ex
Campbell et al., 2014 - Simulated Soccer and Hypoglycaemia
- simulated soccer has lower risk of early but not late onset hypoglycaemia than continuous running
Scott et al., 2019 - HIIT
- 6 weeks of HIIT improved VO2peak and aortic pulse wave velocity (aPWV) to a similar extent as moderate-intensity continuous training (MICT)
- BG levels remained stable during HIIT in fed state but consistently fell during MICT
- HIIT may be preferred training method for T1D
McCarthy et al., 2021 - Cardiopulmonary Exercise Testing (CPET)
- stable BG responses to CPET
- pre-ex hyperglycaemia didn’t influence subsequent glycemic dynamics, it did potentiate alteration in various cardiac and metabolic responses to CPET
- HbA1c a significant factor in determination of peak performance outcomes in CPET
What is Resistance Exercise?
- the use of resistance to muscular contraction to increase muscle strength, endurance, power or size
Turner et al., 2015 - Glycemic Effects of RE
- doesn’t induce acute hypoglycaemia or damage muscle
- BG progressively rose after 1 and 2 sets of RE
- 3rd set of RE reduced exercise-induced hyperglycaemia and returned BG to non-exercise levels
Turner et al., 2015 - Individualised Rapid-Acting Insulin Dose Algorithm
- administration of rapid-acting insulin according to an individualised algorithm reduced the hyperglycaemia associated w morning RE without causing hypoglycaemia in 2h post-ex
Calculation of Post-Exercise Rapid-Acting Insulin Dose
- TDD / 100 = CF
- 0’ minute post-ex BG - 7 = T
- CF x T = Full dose
- 50% x Full dose = A dose
Yardley et al., 2012 - RE and Aerobic Exercise
- performing RE before aerobic ex improves glycemic stability throughout ex and reduces the duration and severity of post-ex hypoglycaemia
Aerobic Exercise Overview
- reduction in rapid-acting insulin before exercise
- ingesting an upper limit of 1g LGI CHO per kg BM per planned hour ex as LGI CHO solution
- make adjustments 30-60 mins pre-running
Strength Exercise Overview
- morning sessions, avoiding bolus before ex, little to no CHO
- if >30 min have recovery CHO handy
- if <30 min administration of bolus to reduce post-ex hyperglycaemia
