Type 2 Diabetes and Prediabetes:A New Understanding of Cause and Treatment

Bruce Latham, M.D.Endocrine Specialists

Greenville Health System

Objectives for this presentation

- Understand the “thrifty genotype and thrifty phenotype” hypothesis as to the origin of insulin receptor signaling pathway mutations in patients with type 2 diabetes- Review the new hypothesis as to the cause of pre-diabetes and type 2 diabetes- Understand why bariatric surgery and extreme diets can reverse type 2 diabetes- Briefly review current research for diagnosis and treatment of type 2 diabetes

Types of Diabetes

Type 1 diabetes – autoimmune destruction of beta cells in the islets of Langerhans inthe pancreas

Type 2 diabetes – chronic hyperglycemia resultingfrom insulin receptor signalingpathway gene mutations

LADA (latent autoimmune diabetes of adulthood)

Diabetes due to pancreatic destruction(pancreatitis, pancreatic resection)

Other genetic causes (Leprechaunism, MODY, etc)

Pre-diabetes: Two finger stick glucoses of 100-125HbA1c 5.7-6.4Post glucola (2hr) glucose 140-199

Diabetes: Two finger stick fasting glucoses of 126 or higher HbA1c 6.5 or higher Post glucola (2hr) glucose >200

Definition of pre-diabetes and diabetes

What causes pre-diabetes and diabetes?

Is it obesity?Is it genetics?Is it bad life-style?

One size does not fit all

- 85 percent of diabetics are overweight- but only 30 percent of overweight people have type 2 diabetes and 15 percent of type 2 diabetics have a normal BMI

The Paradox…

Obesity is not the cause of diabetes

To understand the cause, we need to review insulin action

Only two organs need insulin to internalize glucose:

Skeletal muscleFat

Skeletal muscle transforms chemical energy (glucose) to mechanical work on a “as needed” basis.Fat provides free fatty acids (FFA) for conversion to ATP in mitochondria during prolonged periods of energyneed or during periods of fasting.

The key: both are involved in energy utilization:

There are over 150 known mutations in the insulin receptor or receptor signaling pathwaythat lead to insulin resistance.

Most mutations are detrimental to the survival of the organism.

If this is the case, why are there somany mutations in this signaling pathway?

These mutations may have once been beneficialto Homo sapiens

The “thrifty phenotype” hypothesis

The “thrifty genotype” hypothesis

Hypothesis:

Possible etiology of pre-diabetes and type 2 diabetes

“Thrifty genotype” hypothesis

Possible etiology of type 2 diabetes

Thrifty phenotype hypothesis

Babies with low birth weight (less than 4.3 kg, especially those less than 2.5 kg) have a 7x higher incidence of impaired glucose or Type II diabetes as adults than those who were heaviest at birth.

This is thought due to poor fetal nutrition leading to in utero genetic reprogramming for insulin resistance to increase the chance of surviving poor postnatal nutrition.

These adaptations are beneficial if the individualexperiences poor nutrition postnatally

Example: very low incidence of diabetes in sub-Saharan Africa: poor fetal nutrition + poor postnatal nutrition =no diabetes.

These adaptations are most detrimental if the individual has poor fetal nutrition + good postnatalnutrition = high incidence of diabetes, especially ifobese as an adolescent or adult

Examples:

Pima Indians

Nauru Islanders: “coca-colonization”

Europeans:

Until recently incidence was decreasing

until “glowing pixels of light” and extreme

life spans.

Patients with type 2 diabetes also have a greatlyincreased risk for NASH (non-alcoholic steatosis and hepatitis; i. e. severe fatty liver and liver failure)

In one autopsy series, obesity and/or diabetes wasfound in 20 of 22 patients who died with NASH.

Prerequisites for development of pre-diabetes and type 2 diabetes

- Insulin receptor signaling pathway gene defect- High organ (visceral) fat (liver and pancreas) concentrations. Subcutaneous fat not important.

High organ fat – pancreas and liver

High liver fat – leads to impaired down-regulation of gluconeogenesis and and glycogenolysis and later, NASH

High pancreas fat – (later) decreased insulin production

Interventional Therapies

Weight Reduction in patients without diabetes

Finnish Diabetes Prevention Study (522 subjects)Diabetes Prevention Study (U.S.) (3243 subjects)

Patients treated with:

Regular moderate exercise (2.5-3 hrs/wk)“Optimal” diet (low simple carbs, more dietary

fiber, less saturated fat)

7% weight loss over 3 years58% fewer people developed type II diabetes than in the control groups.

Interventional Therapies

Weight reduction in patients without diabetes

Da Qing trial (577 subjects)

Three treatment groups: diet, exercise, or both

After 6 years, risk reductionof developing T2DM 31%, 46%, and 42%,respectively

(Pan XR, et.al. Diabetes Care 1997, 537-44.)

Interventional Therapies

Weight reduction in patients with diabetes

Lim KG et. al. Reversal of type 2 diabetes: normalisation of beta cell function in association with decreased pancreas and liver triacylglycerol. Diabetologia (2011) 54:2506–2514

• 11 patients with type 2 DM (age 49+/-2.5; BMI 36; 9 male 2 female). 8 non-diabetic control pts• 600 kcal diet for 8 weeks• Pancreatic and hepatic fat measured by MRI after 1, 4 and 8 weeks.• Insulin suppression of hepatic glucose production, 1st phase insulin response measured

• After 1 week, fasting plasma glucose normalized• Insulin suppression of hepatic glucose improved from 43% to 74%.• Hepatic triacylglycerol fell from 12% to 2.9%• 1st phase pancreatic insulin response improved from .19 nmol/min/m to .46 nmol/min/m.• Maximal insulin response became supranormal at 8 weeks (1.36 vs. 1.15 nmol/min/m controls)• Pancreatic triacylglycerol decreased from 8 to 6.2 nmol/min/m

Interventional Therapies

Weight reduction in patients with diabetes

Results

Interventional Therapies

Weight reduction in patients with diabetes

Bariatric surgery

136 studies; 22094 patients. 18% men, 72% women

-Mean age 39 years; mean BMI 46.9 (range 32.3-68.8)

-Gastric banding, gastric bypass, gastroplasty, biliopancreatic diversion or duodenal switch

Operative mortality .1% for restrictive procedures,

.5% for gastric bypass, 1.1% for biliopancreatic diversion or duodenal switch

(Buchwald, et. al. JAMA 292, Oct. 13, 2004)

Interventional Therapies

Weight Reduction

Bariatric surgery

Diabetes completely resolved in 76.8%; resolved or improved in 86%.

Hyperlipidemia improved in 70%.

Hypertension resolved in 62% or resolved or improved in 78.5%

Sleep apnea resolved in 86% and resolved or improved in 83%.

Interventional Therapies

2, 4, dinitrophenol

Current Research

• Blocks oxidative phosphorylation in mitochondria• Causes “runaway” consumption of hepatic fat – conversion to heat rather than to ATP• Once used for weight loss; banned in the 1930’s due to deaths from severe hyperthermia• Still abused by some athletes today to promote rapid weight loss

In the Zucker diabetic rat, can treatment withsmall amounts of 2,4 dinitrophenol reverse diabetes?

When given in very small amounts to these rats, it caused a

• 40% reduction in fasting glucose• 50% reduction in plasma insulin concentration• 90% reduction in hepatic diacylglycerol (fatty acids)

Perry RJ, et.al. Science. 2015 Mar 13;347(6227):1253-6.

What is the concentration of pancreatic and hepatic fatthat is associated with the onset of type 2 diabetes?

So, how does this new information influence day to day treatment algorithms of type 2 diabetes?

First, metformin (inhibits hepatic gluconeogenesis;weight neutral)

Then…what?

Diabetes treatment algorithms are rapidly changing…

Older therapies:

Insulin injectionsSulfonylurea oral agents

often cause weight gain – leading to increased insulin resistance

Interventional Therapies

Newer diabetic medications which cause weight loss:

GLP-1 agonists: exenatide (Byetta), liraglutide(Victoza), dulaglutide (Trulicity), etc.

SGLT 2 inhibitors: dapagliflozin (Farxiga), canagliflozin (Invokana), empagliflozin(Jardiance)

Take Home Points

• Obesity itself does not cause type 2 diabetes.• Type 2 diabetes is the result of an insulin receptor or receptor pathway mutation in some individuals, present from birth.• It is the combination of the mutation – along with visceral

fat – that may lead to type 2 diabetes.• The visceral fat content needed to cause type 2 diabetes is

not yet known.• Weight loss and exercise can prevent and may reverse

diabetes in some if not most individuals.

Prediabetes and type 2 diabetes are diseases of our times.

The rapid change in human culture from hunter-gatherers to the agricultural age, and now the industrial age has made a once apparently beneficial mutation in our genetic code a detriment.

Because of the rapid nature of our cultural change, we as a species have not had time to adapt to our new environment. Since those of us in western societies no longer eat or exercise as our distant ancestors did, this mutation has left many at risk for cardiovascular disease and type II diabetes.

Take Home Points