Diabetes and Diving • ISAM • San Salvador 2017 • Janelle Sanda, MD • No disclosures
Diabetes and Diving What’s changed? • Historically, the diving medicine community has maintained a conservative position and concluded that insulin-requiring diabetes mellitus (IRDM) should be an absolute contraindication for scuba diving. • This view has changed over the last 20 years. • A substantial number of divers are diving successfully with diabetes
Outline • Diabetes epidemiology and brief review of management. • Diabetes & diving, potential problems • Guidelines from UHMS/DAN Workshop for diving with diabetes.
Introduction • Insulin is required to allow glucose to move from the blood into cells where it can be utilized for energy production. • Diabetes results from inability of the glucose to enter the cells, either due to deficiency of insulin or to ineffective response to insulin.
Major Types of Diabetes • Type 1 diabetes results from loss of Beta cells in pancreas and inability to produce insulin. Require insulin for treatment. • Type 2 diabetesresults from insulin resistance (a condition in which they body’s cells fail to properly respond to insulin). Insufficient production may follow. Rx with diet, exercise, oral or injectable meds. • Pre-diabetes is defined as having FBS levels that are above normal range (100), but less than for dx of diabetes (126). These people are at increased risk for developing diabetes over the next 10 years (5-10%/yr).
Diabetes stats • Worldwide, 8% of adult population has diabetes, 90% of those are Type 2 DM • In U.S., over 29 million are living with diabetes and another 86 million with prediabetes • Sharp increase in new dx from early 90’s through 2009, peaking at 1.7 million/yr • Rates falling gradually since 2009
Dangers of Diving with Diabetes • Hypoglycemia when submerged, which could lead to drowning or improper ascents and DCI. • Increased risk for underlying vascular disease and acute events when diving
Hypoglycemia is Common • Symptomatic hypoglycemia is common in individuals with Insulin Requiring Diabetes Mellitus (IRDM) . Minor episodes of hypoglycemia may occur once or twice a week • Severe hypoglycemia (those who need help of someone else to treat) in those with diabetes also common: • 5%/yr for conventional and 8%/yr for intensive insulin Rx. 2-4% Mortality
Hypoglycemia • Occurs when insulin levels aren’t properly matched to food intake and/or exercise • Excessive dose or ill-timed or wrong type of insulin • Decreased suppy of glucose ( missed meal) • Decreased glucose production (EtOH intake) • Increased glucose utilization (exercise)
Hypoglycemia and Exercise (Diving)– Important Considerations • Timing of after-meal exercise • Pre-meal Insulin dose • Intensity of exercise • Duration of exercise • Any preceding hypoglycemia • Hypoglycemia causes impairment of glucose auto-regulatory mechanisms and decreased hypoglycemia awareness • Metabolic sugar control
Hypoglycemia in Type 2 DM • Less common than with Type 1 DM, even when treated with insulin. • UKPDS documented 11.2% with severe hypoglycemia over 6 year period, compared to over 60% with Type 1 DM • Oral hypoglycemic agents in UKPDS • 3.3% with sulfonylureas over 6 years • 2.4% with metformin • Rates may be higher with combination Rx • Hypoglycemia may be more prolonged
Hypoglycemia Low blood glucoses trigger compensatory mechanisms (glucagon, epinephrine) that help restore normoglycemia. turn off insulin production increase glucose mobilization Signs and sx of hypoglycemia are due to combination of adrenergic, cholinergic and neuroglycopenic mechanisms.
Hypoglycemia Sx/Signs • Shaky, Sweaty • Feeling weak and hungry • Anxiety, irritability • Slowed mental processing, confusion • Impaired motor skills, blurred vision • Loss of consciousness • Seizures • Death
Some people have decreased early symptoms of hypoglycemia. They may lose consciousness without ever knowing their blood glucose levels were dropping Hypoglycemia unawareness tends to happen to people who have had diabetes for many years. Hypoglycemia Unawareness
Hypoglycemia Unawareness • It is more likely in • People who have neuropathy • People with tight control with HbA1c <7% • People on medications, such as beta-blockers that can mask some early symptoms of low blood sugar
Hypoglycemia Unawareness • A severe hypoglycemic reaction can cause temporary (1-2 week) reduction in both hypoglycemic awareness and compensatory mechanisms.
Insulin Pumps • Use either regular or rapid acting insulins. • Continuous infusion for basal insulin • Pre-meal bolus injection • Unhook for up to an hour while in water. Danger of ketoacidosis if no insulin for 2 hours or more.
Type 2 DM Oral Agents • Sulfonylureas (glipizide, glyburide)- hypoglycemia risk • Biguanides (metformin) • Meglitinides (Prandin, Starlix)-hypoglycemia risk • TZDs (Avandia, Actos) • DPP-4 inhibitors (Januvia, Onglyza) • SGLT-2 inhibitors (Invokana) • Alpha-glucosidase inhibitors (Precose) .
Injectable GLP-1 agonists • Liraglutide (Victoza) • Exenatide (Byetta, Bydureon) • Low risk for hypoglycemia, unless used in combination with insulin or sulfonylurea. • Slows gastric emptying, so may worsen GERD
Diabetes & Heart Disease • Glucose latches onto lipoproteins. Glucose-coated LDL remains in the blood-stream longer and leads to plaques. • People with diabetes tend to have low HDL and high triglyceride levels, both of which boost the risk of cardiovascular and other vascular disease • As a result, in people with diabetes: • Heart disease is two to four times as common. • Heart disease occurs at younger age. • Ischemic symptoms are more likely to be unrecognized. • Acute cardiac events are more likely to be fatal.
Risk Factors for ASCVD • Anyone with the following is at higher of cardiac problems during any exercise program • Age >35 years with diabetes • Age >25 years and • Type 2 diabetes of >10 years duration • Type 1 diabetes of >15 years duration • Presence of any additional risk factor for coronary artery disease (smoking, obesity etc) • Presence of small vessel disease (proliferative retinopathy or nephropathy) • Peripheral vascular disease • Autonomic neuropathy
Other Diabetic Complications • Nephropathy • Retinopathy • Peripheral neuropathy • Autonomic neuropathy • GI motility issues or bladder problems • Blood pressure instability • Loss of the typical warning signs of MI, low BS
History of Divers with Diabetes • Traditionally, diabetes (especially with insulin treatment) was considered an absolute contraindication to diving. • Results of survey in early 90’s showed that a substantial number of people with diabetes were diving without incident • DAN observational study of divers on insulin to explore the safety and feasibility of allowing diabetics to dive.
Divers Alert Network Project • 40 IRDM divers (+ 43 Controls) took part and agreed to adhere to the protocol approved for the study • Plasma glucose (PG) had to be >80 mg/dL (4.4.mmol/L) with stable or rising values • Maintained records of their insulin dosages, diet & exercise throughout research trip
Protocol • Plasma Glucose recorded • 60 minutes pre-dive • 30 minutes pre-dive • 10 minutes pre-dive • immediately post-dive • Used Bayer Glucometer Elite • Time/depth profiles of all dives were recorded with downloadable dive computers (PDE)
Details of Dives & Divers • Majority of dives, 2.7 per day, were made from live-aboard dive boats • Locations: Caribbean, Mexico, Bahamas, Honduras, Cayman Islands and Belize • minimal or modestly stressful conditions in tropical or subtropical waters • Most divers had been diving for at least 5 years and had diabetes for 15 years • Diabetes was already present in 31 divers at the time they obtained scuba certification
Hypoglycemia Episodes • Low Plasma Glucose reported before & after diving in 18 cases • IRDM divers took extra glucose before 42% of dives • Needed to raise PG > 80 mg/dL • Post-dive plasma glucose fell: • IRDM: < 70 mg/dL in 7% • Minimum 41 mg/dL • Control: < 70 mg/dL in 1% • Minimum 56 mg/dL • Significant difference p<0.05
Hyperglycemia • Moderate levels of hyperglycemia (>300 mg/dL: 16.7 mmol/L) noted in 8 divers on 67 occasions pre-dive • Also occurred post-dive in 15 divers on 17 occasions • No episodes of symptomatic hyperglycemia
Limitations of Studies • All dives were • Uncomplicated recreational dives • Minimal or modestly stressful conditions • Tropical or subtropical waters • Additional stress might cause more dramatic changes in glucose levels • Increased equipment burden – dry suit, weights, tech? • Thermal challenge – cold water • Extreme exposure profiles – Decompression dives • Emergency situations – extra unexpected swimming
UHMS/DAN Workshop 2005 • 50 experts from 7 countries reached consensus on diving for diabetics • Guidelines published for recreational diving with diabetes • Covered selection of appropriate divers, scope of diving and glucose management protocol day of diving. • World RSTC (Recreational Scuba Training Council) endorsed in 2006
Selection and Surveillance of Diabetics in Scuba Diving • Age limit is suggested at age ≥18 • Diving after start of new or changed therapy • OHA 3 months; 1 year for insulin • No episodes of hypoglycemia or hyperglycemia requiring emergency intervention for at least one year • Good hypoglycemia awareness • HbA1c ≤9% when measured no more than one month prior to initial assessment and at each annual review • No significant secondary complications: no proliferative retinopathy, nephropathy, ASCAD, PAD, significant autonomic or peripheral neuropathy.
Selection and Surveillance of Diabetics in Scuba Diving • PCP / diabetologist should carry out annual review & determine that diver has good understanding of disease and effect of exercise • Consult an expert in diving medicine, if needed • Carry out formal evaluation for silent ischemia for candidates over ~35-40 years • After the initial evaluation, periodic surveillance for silent ischemia can be in accordance with accepted local guidelines for the evaluation of diabetics • Candidate documents intent to follow protocol for divers with diabetes and to cease diving and seek medical review for any adverse events during diving possibly related to diabetes
Scope of Diving by Diabetics • Do not dive: • Deeper than 100 fsw • Duration> one hour • Decompression stops • Overhead environments; caves etc. • Prolonged cold or arduous diving • Need non diabetic buddy who knows about diabetes & what to do
Glucose Managementon the Day of Diving • Blood glucose ≥150 mg∙dL, stable or rising before entering the water • Glucose checks @ 60 mins, 30 mins & just before diving • Alterations in doses of OHA medication or insulin on the evening prior to or on the day of diving may help • Postpone if BG > 300 mg∙dL-1 (16.7 mmol∙L-1) • Rescue medications • Carry oral glucose readily accessible during all dives • Have parenteral glucagon available at the surface • If hypoglycemia noticed underwater, the diver should surface, establish positive buoyancy, ingest glucose and leave the water • Check BG frequently for 12-15 hours after diving • Ensure adequate hydration on days of diving • Dive log to include BG results, info pertinent to DM management
Concerns for Relaxing Diving Rules • Risk of severe hypoglycemic events including seizures & LOC • Not predictable for individual • Conditions may change rapidly • Serious medical event UW resulting in serious consequences • Need education and experience in adjustment of insulin dosing & caloric intake • Additional training for all divers, dive leaders & support personnel to recognize & treat hypoglycemia events • Ability to differentiate diabetes-related problems & DCI • Diving certifications are 'for life' basis in US • Unlike many other countries
Other Restrictions • FAA – Diabetes & Pilots (3rd class) • Detailed examination on first certification • Subsequent: • Must carry memory glucometer • Every 3 month doctor evaluation • Annual review • >40yrs must have ECG and stress test every 5 yrs • During flight operations • If pre flight PG >300 or < 100 mg/dL flight canceled • During flight must test every hour; <100 take glucose; >300 must land at nearest airport
Diving with IRDM Diver • Team of Three • 3-Person buddy team provides better situational awareness • 2 people to effect a rescue • Team Members • Must be aware of condition and recognize signs of hypoglycemia • Hand signals for hypoglycemia (“L” sign) • Know how to check BG levels and administer glucagon, if needed. • Ability to “call” the dive if conditions deviate from general rules for IRDM Diving.
Diving with IRDM Diver • Should also have available oxygen and first aide kits and be trained to use it.
Summary • Diving & Diabetes = Potential for Big Risks • Traditionally Diabetics were excluded from diving • There are IRDM people diving • Guidelines are in place for diabetics to help minimize their risks and do relatively easy dives • Protocols require strict adherence • Team of Three for Diving • Failure to follow procedures can result in death.